Philippines – Japan Joint Workshop
on Materials for Safe andSustainable Society 2012
The University of the Philippines Diliman,
Quezon City, Philippines
December 6, 2012

Supported by the University of the Philippines Diliman
and Shizuoka University

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Characterization of Water Hyacinth Fiber Treated at Different Alkali
Concentration and Immersion Time
Joseph Ortenero*, Terence Tumolva
Department of Chemical Engineering, University of the Philipppines
Diliman, Quezon City 1101, Philippines*
e-mail: josephortenero@gmail.com

1. Introduction
The use of natural fiber as reinforcement
material has gained a lot of attention inrecent years. This can be attributed toincrease in environmental concern broughtby recent environmental challenges. In
addition, governments around the world
introduced strict legislation to find ways inusing renewable resources and reduce
dependence on synthetic materials.
In natural fiber reinforced polymer(NFRP) several fibers such as jute, flax,
hemp and several others have proven to beeffective as reinforcement material. However,there is concern regarding production as
demand for those fibers may compete withexisting land devoted to food production. In
this light, water hyacinth (WH) fiber could
be tapped as possible substitute as this plant
which is considered to be a pest in many
parts of the world is excessively abundantlocally. In addition, this plant has highgrowth rate.

with NaOH was done using tensile andmorphological property evaluation as well as
FT-IR study.

2. Experimental
The NaOH used in alkali treatment waspurchased from B.E. Scientific, Inc..The
water hyacinth stalks were obtained at
Laguna de Bay and decorticated at
PTRI-DOST in Taguig.
The WH fibers were cut to 13 cm length.
The fibers were soaked for 7 days to remove
some lignin, waxes and any adhering dirt.
The fibers were then soaked in alkali
solution according to time-concentration
combination of parameter. After the required
immersion time the fibers were neutralizedwith equimolar concentration of HCl
solution.
The individual fiber was then air-dried
and glued on board frame for tensile
property evaluation using Shimadzu AGS-X
at crosshead speed of 0.5 mm/min and 25
mm gage length. Morphological property
evaluation was done using Hitachi S-3400N.
FTIR-ATR study was done to determine
surface structural changes.

3. Results and Discussion

Fig. 1.
Water Hyacinth fiber obtained bydecortication to extract the fiber from stalk.

Chemical treatment on natural fiber isnecessary to improve interaction with matrix.
The natural fiber undergoes surface
structural and morphological changes duringchemical treatment. It is this surface
transformation that will play significant rolein the resulting composite. In this paper,
characterization of WH fiber after treatment-1-

Figure 2 shows the tensile strength of thefiber at different alkali treatment period as afunction of NaOH concentration. The
strength of the fiber decreased as a result of
the chemical treatment. The trend is as theimmersion time increases tensile strength
decreases except for the 24 hr immersion
time. The elongation of the fiber was
improved due to alkali treatment with the
10%NaOH concentration showing thehighest change as exhibited in Figure 3. The
stiffness of the fiber was lowered for all
samples as a result of the treatment shown inProceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Figure 4. These changes in tensile propertiesof the fiber were due to removal of lignin
and hemicellulose backbone. Several studies
also suggest that alkali treatment leads to anincrease in the amount of amorphous
cellulose at the expense of crystalline
cellulose1.

A

B

C

Fig. 5. SEM micrographs of WH fiber at 250x
magnification. (A) 2hr & 5%NaOH, (B) 12hr &10%NaOH ,(C) untreated.
Fig. 2. Tensile strength of WH fiber at different
concentration as a function of immersion time.

FTIR-ATR spectra for untreatedWH fiber showed a broad and intense bandin the range of 3100-3800 cm-1 due to the–OH vibration of cellulose structure asshown in Fig. 6. The dip at 3400 cm-1
decreased for treated samples. This increasein transmittance will enhance the ability of
the fiber to repel moisture due to suppressionof –OH group across the fiber surface.

Fig. 3. Elongation at different concentrationand immersion time.

Fig. 6. FTIR-ATR spectra of treated anduntreated WH fiber.

4. Conclusion
Fig. 4. Elastic modulus at different concentrationand immersion time.

SEM micrographs of untreated WH fiber
show significant amount of waxy natural
material covering the entire surface of thefiber as presented in Figure 5(c). Also shownin the figure are images of treated WH fiber
at two different concentration and immersion
time. It can be observed that alkali treatment
partially removed the waxy material fromthe surface of the fiber.

-2-

Alkali treatment decreased WH fiber
strength and stiffness. Morphological study
revealed that alkali treatment reduced thewaxy material covering the surface of thefiber. FTIR-ATR result showed reduction of–OH group across the fiber surface.

References[1] M. Mizanur Rahman, A. Mallik, M.
Khan, J. Appl. Polym. Sci. 105 (2007),
3077-3086.
[2] A. Gomes, K. Goda, J. Ohgi, JSME Int.
J. 47-A (2004), 4.

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Fatigue Property of Jute Monofilament
Kazunori UEMATSU1*, Hideaki KATOGI2, Yoshinobu SHIMAMURA3, Keiichiro
TOHGO3 and Tomoyuki FUJII3
1 Graduate Student of Shizuoka University,
3-5-1, Johoku, Naka-ku, Hamamatsu, 432-8561, Japan
2 Department of Mechanical Engineering, Kanagawa University,
3-27-1, Rokkakubashi, Kanagawa-ku, Yokohama, 221-8686, Japan
3 Department of Mechanical Engineering, Shizuoka University*email: kuematsu@mechmat.eng.shizuoka.ac.jp

1. Introduction
With the increased interest innatural environments problem in recent
year, green composites, which weremade out of natural fibers andbiodegradable plastics, are attracting
attention. Green composites are applied
for door-trim of automotives, cases ofmobile phone and so on1. On the other
hand, in order to apply for load-bearing
components,
unidirectional
reinforcement techniques of natural
fiber spun yarn have been developed toincrease specific modulus and strength2,3.
For applying green composites toload-bearing components，it is necessary
to investigate fatigue property of green
composites. In order to elucidate thefatigue property of green composites, itis necessary to clarify fatigue propertyof natural fibers that is a constituent ofgreen composites. However, fatigue
property of natural fiber has not beenclarified. In this study the fatigue
property of jute monofilament which
composes jute fiber was investigated.

2. Materials and Specimen
2.1. Structure of natural fiber
Figure 1 shows a schematic of
typical natural elementary fiber. Openhole, called lumen, exists in the centerof an elementary fiber. Microfibril (MF)is a bundle of cellulose, which is bonded
by hydrogen bonding, surrounds aroundcell walls. MF has an angle to the axial
direction, which determines the axial
stiffness. MFs are adhered byhemicelluloses
andlignin.
Monofilament consists of elementaryfibersthatareadheredbyhemicelluloses, pectin and lignin.

Fig.1

Structure of natural elementary

2.2. Specimen
Alkaline treatment was performedforwashing
juteyarns.
Jute
monofilaments were extracted from thewashed yarns. The diameter of amonofilament was measured from two
perpendicular directions along thelength. The cross sectional area of afractured portion was estimated byelliptical approximation using the above
data. Figure 2 shows a specimen fortensile tests and fatigue tests. According
to JIS L 1069, U-shaped specimens wereprepared. In fig.2, cutting line was cut
after specimen was gripped.
30
10

10
Adhesive

20

Monofilament
Mounting
part

Cutting line

[Unit : mm]

Fig.2 Specimen-3-Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

360
Stress amplitude a [MPa]3. Tensile test of jute monofilament
Qausi-static tensile tests wereconducted to measure tensile strength.
The number of specimen was 30. The
cross head speed was 1mm/min and thegauge length was 10mm. Figure 3 shows
the S-S diagram of jute monofilament
and Table 1 shows the mechanicalproperties. Tensile strength and Young’s
modulus of jute monofilament have ascatter as shown in fig.3. Therefore, it isnecessary to consider this scatter whenthefatigue
propertyofjutemonofilament is discussed.

300
240
180




120
60

0
100 101 102 103 104 105 106
Number of cycles to failure Nf [cycles]

Table 1 Mechanical properties of jute monofilament

Fig.4

S-N diagram of jute monofilaments

Tensile strength Young's modulus
Average
S.D.
Average S.D.
149MPa 147MPa 16GPa 5GPa

Jute

700

10μm

Stress  [MPa]

600
500
400
300
200
100
0
0

0.5

1

1.5 2 2.5
Strain  [%]3

3.5

Fig.5 Jute monofilament after fatigue

Fig.3 S-S diagram of jute monofilaments

5. Conclusions

4. Fatigue test of jutemonofilament(1) The fatigue property of jutemonofilament seems to be superior.
(2) Splitting between elementary fibers
and pull out of secondary wall were
found after fatigue failure.

Fatigue testing was conducted atroom temperature. Loading frequency
was 10Hz and the gauge length was
10mm. The stress ratio is 0.1 and the
maximum stress was 60 to 120% of thetensile strength.
Figure 4 shows the S-N diagram.
The error bar at 1 cycle is the standard
deviation of the tensile strength.
Fatigue strength at 106 cycles was
about 50% of the tensile strength.
Therefore, fatigue property of jutemonofilaments seems to be superior.
Figure 5 shows the fracture portion after
fatiguetesting.
Splittingamong
elementary fibers and pull out ofsecondary wall in an elementary fiber
were found.

Reference
1. F.P.L.Mantia,
M.Morrela,Composites Part A, Vol.42, No.6
(2011), pp.579-588.
2. O.A.Khondker, U.S.Ishikua, A.Nakai
and H.Hamada, Composites Part A,
Vol.37, No12, (2006), pp.2274-2284
3. G.Ben, Y.Kihara, K.Nakamori and
Y.Aoki,Advanced
Composite
Materials, Vol.16, No. 4, (2007),
pp.361-376.
4. M.A.Meyers, P.Y.Chen, A.Y.M.Lin,Y.Seki, Progress in Materials
Science, Vol.53, No.1, (2008),
pp.152-206-4-

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Microencapsulated Coconut Oil as a Buffering PCM for Textile Applications
Hyacinth Mae G. Tambago*, Thor Alexis S. Sazon, Gilbert S. Casuyon,
Al Christopher C. de Leon, Rizalinda L. de Leon
Department of Chemical Engineering, Melchor Hall, University of the Philippines,
Diliman, Quezon City 1101, Philippines
TEL: +63-2-981-8500 loc 3114 TEL&FAX: +63-2-929-6640*e-mail: hyacinth_mae.tambago@up.edu.phformaldehyde as shell materials and sodium
dodecyl sulfate (SDS) surfactant as emulsifier.

1. Introduction

Thermal properties of the microencapsulated
coconut oil particles were measured and thesurfactant concentration was investigated for
its effect on PCM content, particle size, andmechanical strength. Based on theseproperties, the potential of the synthesized
microencapsulated coconut oil for textile
applications was evaluated.

Phase change materials (PCMs) are thermalenergy storage substances that have high latentheats of fusion. During melting or solidification,these substances can store or release large
amounts of energy with temperatures maintained
constant at their melting point. Due to thisproperty, PCMs can be incorporated in window
textile and composites to serve as a thermal
barrier, reducing energy consumption forcooling of spaces against solar heat. For suchapplications, encapsulation of the PCM isnecessary to contain the material in its liquid
phase and prevent material losses due toevaporation. When particles are contained insolid, polymeric shells of 1-1000 micrometers indiameter,theprocessiscalledmicroencapsulation. Microencapsulated PCMs
exhibit improved heat transfer and cyclingstability due to smaller size and higher surfaceto-volume ratio.
One advantage of microencapsulation is thatit allows PCMs to be incorporated in textile,which requires the size of the particles to be in
the range of 3-10 μm. PCM content of
microcapsules for this application is 80-85% byvolume and the polymeric shell is around 1 μm
thick [1].
Coconut oil is a relatively cheap andabundant natural material in the Philippines thatcan function as a buffering PCM. With a melting
temperature of 25-27°C slightly lower thanambient temperature during the day, and highlatent heat of fusion of 54-126 J/g [2], coconut
oil can aid air-conditioners in thermal regulationof cooled spaces. In this study, microcapsules ofcoconut oil as PCM were synthesized via in-situ
polymerization
using
melamine
and

2. Experimental
The oil/water emulsion was prepared bymixing coconut oil, water, and SDS using ahomogenizer. Two SDS concentrations wereused: 1.25% and 3% SDS. Melamine,
formaldehyde, and water were mixed underbasic conditions in creating the pre-polymer
solution, which was then added into theemulsion.
The
resultingmixturewas
continuously homogenized and then cooled,filtered, and dried to obtain the microcapsules.
The chemical structure of coconut oil andmicroencapsulated coconut oil were determinedusing a Shimadzu Prestige 21 FTIR
spectrophotometer. Thermal properties of the
microcapsules were measured using a Shimadzu
DSC-50. Particle sizes were measured fromoptical microscopy images and the mechanicalstrength of the microcapsules was qualitatively
evaluated using a centrifugal shear force test.

3. Results and Discussion
The FTIR spectra of coconut oil and thesynthesized microcapsules are shown in Fig. 1.
With respect to the spectra of pure coconut oil,the appearance of a broad band in the 3703-3036-5-

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

cm-1 region and peaks at 814, 1520, 2931, and1469, and 1173 cm-1 in the spectra of the
microcapsules correspond to melamine andformaldehyde chemical groups and the chemical
linkages that result from polymerization. This
indicates formation of melamine-formaldehyde
polymer and successful encapsulation of coconut
oil.

exhibited lower mechanical strength, asevidenced by an oil leak from the microcapsules.
This could be due to formation of rough surfaces
at higher surfactant concentrations, resulting in
microcapsules with reduced mechanical strength[3].
Although the microcapsules synthesizedfrom the 3% SDS emulsion resulted in smaller
particles, they are still not sufficiently small for
textile applications. The PCM content could not
be determined without the latent heat of fusionof pure coconut oil and imaging of an open
microcapsule is required to determine thethickness of the polymeric shell.

(a)
(b)
(c)

4. Conclusion
Coconut oil has been successfully
encapsulatedbymelamine-formaldehyde
polymer. The microencapsulated coconut oil
exhibited a melting point within our comfort
zone. Higher surfactant concentration in the oilwater emulsion resulted in smaller and morehomogeneously sized particles with higher
coconut oil content but with lower mechanicalstrength. In order to satisfy requirements for
textile applications, synthesis of much smaller
microencapsulated coconut oil particles withhigher mechanical strength should be explored.
Further tests such as characterization of purecoconut oil, thermal cycling stability andmorphological analysis of microcapsules, andthermal and durability analysis of fabrics treatedwith microencapsulated PCM should be
conducted in order to fully characterize thepotential of microencapsulated coconut oil forthis application.

Fig. 1. FTIR spectra of a) pure coconut oil, b)
microcapsules with 1.25% SDS, and c)
microcapsules with 3% SDS.
Thermal properties of microcapsules
synthesized from 1.25% and 3% SDS derived
from DSC thermograms are tabulated in Table 1.
The average peak melting point of the
microcapsules is 24.61°C, which is within therange of comfort temperature. Microcapsules
prepared from 3% SDS emulsion exhibited
higher latent heat of fusion compared to thatwith 1.25%. This also indicates thatmicrocapsules prepared using a higher surfactant
concentration contain a larger amount ofcoconut oil per unit mass.
Table 1. Thermal and physical properties of
microencapsulated coconut oil.
Melting temperature, °C
Heat of fusion, J/g
Mean particle diameter, μm
Particle diameter range, μm

Microcapsules from
1.25% SDS
3% SDS
24.55
24.67
23.15
44.69
27.87
11.15
11.00-55.98
3.43-19.73

References[1] M. V. Parys (2006). Smart Textiles using
Microencapsulation Technology. In S. K.
Ghosh, Functional Coatings by Polymer
Microencapsulation(pp.
221-258).
Weinheim: WILEY-VCH Verlag GmbH &Co. KGaA.
[2] A. Rudd, ASHRAE Transactions 99 (1993)
339-346.
[3] H. Zhang& X. Wang, Colloids andSurfacesA:
Physicochemical
andEngineering Aspects 332, (2009) 129–138.

The mean particle diameters and size rangeof the microcapsules are also tabulated in Table
1. Surfactant concentration of 3% in theemulsion yielded smaller particles with anarrower size distribution than those formed byusing 1.25% SDS. In the centrifugal shear force
test, microcapsules prepared from 3% SDS-6-

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Stress Corrosion Crack Initiation in Austenitic Stainless Steel under
High-Temperature and Pure Water Environment
Yutaro Miura1, Akihiro Kenmochi2
Tomoyuki Fujii3, Keiichiro Tohgo3 and Yoshinobu Shimamura3
1
Under graduate student of Shizuoka University
2
Graduate student of Shizuoka University
3
Department of Mechanical Engineering, Shizuoka University,
3-5-1Johoku, Naka-ku, Hamamatsu 432-8561, Japanaymiura@mechmat.eng.shizuoka.ac.jp

1. Instruction
2.3
Stress corrosion cracking (SCC) is an
inherently complicated material degradation
phenomenon
inducedbycertaincombinations of material, environment, andstress condition. It has been reported that
SCC occurs under the corrosive conditions inchemical plants and nuclear power plants. It
is important to clarify the crack initiation andpropagation behavior by SCC under the
corrosive conditions from the viewpoint ofremaining lives in long-term service.
In this paper, the constant tensile load tests
under High-Temperature and Pure Water
Environment, this is equal to simulated
primary water environment in a boiling water
reactor (BWR) were carried out for sensitizedstainless steel to investigate influence of
applied load and loading time on crack
initiation propagation behavior by SCC.

Experimental environment

The constant tensile load tests undersimulated primary water of boiling water
reactor are carried out. Table 2 shows the test
conditions.
At first, the specimens were pre-immersed
in 48 hours. After that, the load was applied.
After the experiments, the specimens were
etched by 10% oxalic acid to remove oxide
film and expose grain boundary on thespecimen surface. The number of cracks andmaximum crack length were measured byusing an optical microscope and scanningelectron microscope (SEM) in order toevaluate the influence of the applied load andloading time on the crack initiation andcoalescence behavior by SCC.

2．Material and Experiment
2.1

Material and Specimen

Austenitic stainless steel type 304 was used.
The stainless steel was sensitized by heat
treatment in order to accelerate crack
initiation by SCC. Table 1 shows thechemical composition of the material.
Figure 1 shows the geometry of thespecimen. The specimens were machinedfrom the bulk material after the heat
treatment and their surfaces were polishedand buff-finished. The specimen has threedifferent cross-section parts in order to lorddifferent level of stresses at a time. In orderto accelerate crack initiation by SCC, thecrevice was formed on the specimen surface
by using graphite fiber wool (GFW).

Fig.1. Shape of specimen
Table2.Test condition
Temperature
Pressure
Conductivity
Dissolved oxygen
concentration

Table1. Chemical composition of SUS304
C
Si Mn
P
S
Ni
Cr
Fe
0.06

0.47

0.82

0.03

0.003

8.05

18.16

Stress levels

Bal

-7-

288℃
8MPa
0.1S
8ppm
175MPa210MPa250MPaProceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

3．Experimental results

Figure 4 shows the histogram of thefrequency of cracks as a function of crack
length less than 100m when the appliedstress is 250MPa. The most frequent crack is
about 60m in length when the crack is lessthan 100m. The frequency curves between
the crack length and the number of crack isbell-shaped. Therefore, it seems that theprobability of the crack initiation by SCC isnormal-distributed. The mean value of thenormal-distribution is 52m and the varianceis 15m, irrespective of applied load.

Figure 2 shows surface observation under
the applied load of 250MPa for 120hours.
Figure 2(a) is overall view of the specimen
surface, and Fig. 2(b) is the magnified viewsof part A in Fig.2 (a). Many cracks at normal
direction to loading direction are observed in
Fig.2 (a). The stress corrosion cracks initiatedat the grain boundary in Fig. 2(b).

Fig.4. Number of cracks as a function of time.

(a) Over all veiw

Fig.6. Histogram of number of cracks as afunction of crack length under 100m (250MPa).

(b) Detail of A

4．Conclusion

Fig.2.Cracks on specimen surface(120hr,250MPa)(1) The number of cracks and maximum
crack length increases with increasing
loading immersion time and applied load.
(2) The probability of the crack initiation by
SCC is normal-distributed. The mean andvariance are constant irrespective of
applied load.

Figure 3 shows the number of cracks as afunction of loading time. The error bars
denote the maximum and minimum numberof cracks. The number of cracks increases
with increasing loading time and applied
load.

-8-

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Synthesis of Furfural from Locally Available Agricultural Residues in thePhilippines
Rodel D. Guerreroa*, Emmanuel P. Belostrinoa, Mark Louis H. Laguraa, Billy Joe Y. Uya,Terence P. Tumolvaa and Masatoshi KubuochibaDepartment of Chemical Engineering, University of the Philippines,
Diliman 1101 Quezon City, Philippines
TELEFAX: +6329296640b
Department of Chemical Engineering, Tokyo Institute of Technology,
2-12-1 O-Okayama Meguro-ku, Tokyo, 152-8552 Japan*email: rodeldayagguerrero@gmail.com

1. Introduction
Furfural, with an IUPAC systematicname of 2-furancarboxaldehyde andmolecular structure is a clear and colorlessoily liquid with a benzaldehyde-like odor.
Furfural has an array of uses thus it is now
widely used in large quantities as a solvent,to accelerate vulcanization, as an ingredient
to production of phenolic resins and manymore.
In producing furfural, materials rich inpentosans are used. Pentosan is found inhemicellulosic fibers like bagasse, hulls, nut
shells, corn cobs and oats. After extraction,
pentosan is converted to furfural.
The Philippines produces a myriad of
agricultural products. The country capitalizes
on its fertile lands and its tropical climate tosupport a thriving agricultural industry. Of
the 30 million hectares of land in the country,
40% is agricultural. It also shows that thePhilippines main agricultural crops are
sugarcane, which accounts the largest
production volume, followed by palay,
coconut, banana and corn.
Given the data and the top agricultural
products of the country, it is possible todeduce the most viable option for raw
materials in producing furfural. It follows
that the crops with the highest production
volume generate the highest amounts ofwaste, hence making them good candidates
for raw materials.
With those in mind, finding locallyavailable raw materials for the production of
furfural, the important intermediate for the
production of furfuryl alcohol, could prove
to be beneficial. The recognition of new
alternatives could increase the feasibility of-9-commercialization of furfural. The full
utilization of our agricultural residues, by
turning them into sources for plastic
production and other applications, could
greatly help in boosting the economy. Also,
making the manufacturing process more
adapted to the Philippine setting can attract
investors and companies to construct a
furfural plant in the Philippines. And lastly,
the Philippines can satisfy our demand in
furfural and could also become a major
supplier of furfural in the world market.
Thus, this paper proposes locallyavailable raw materials that have not beenpreviously used in furfural production.
Based on the agricultural crops production
data in the country, the raw materials chosen
are coconut shell, coconut husk, pineapple
bagasse, and water hyacinth stalks.

2. Experimental
Materials
The raw materials used were coconut
shell, coconut husk, pineapple bagasse andwater hyacinth stalks.

Figure 1. The raw materials used in the study.

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Synthesis of furfural
A pulverized air-dried sample of the raw
material (0.100 g) was placed inside a 10 mL
glass test tube. Dilute sulfuric acid (0.2 M)
solution of 3.5 mL in volume was thenpipetted to the test tube and covered with acap. The test tube was immersed in an oilbath and was heated for the specified
digestion period (10, 15, 20 minutes) at 453
K. at the end of the digestion time, the test
tube was cooled promptly by being
immersed in a water-cooled bath. The test
tube was opened and the product was filteredout and washed with hot water to a 50 mL
beaker. The furfural was precipitated withtheadditionof
20mL
2,4-dinitrophenylhydrazine solution (2,4
DNPH). The precipitate was then filteredand first washed with 2 M HCl solution andfollowed by washing with distilled water.
The
precipitate
yieldoffurfural
2,4-dinitrophenylhydrazine is quantitative(Demirbas, 2006) (Kazemi et. al., 2009).

3. Results and Discussion
Tables 1 and 2 show the average mass
yield and standard deviations for each raw
material at different digestion times:
Mass Yield
Raw Material

10 mins

15 mins

20 mins

Coconut Husk

4.30695.5132

5.546

Coconut Shell

6.27296.92627.2108

Pineapple Bagasse

3.5941

4.99895.5208Water Hyacinth
2.60672.6888
Table 1. Average mass yields.

3.6369oil bath and the possible escape of furfuralvapor from the reaction tubes.
Figure 2 shows that the values of themass yield increase with increasinghydrolysis time.

Figure 2. Mass yield as a function ofhydrolysis time (T = 180 deg Celsius)

Coconut shell gave the highest R2 value
which indicates that it is the most sensitive
to changes in hydrolysis time. Increasing thehydrolysis time further will give higher mass
yields.

4. Conclusion
The proposed experimental design was
found to be successful in the synthesis offurfural. The method used is alsosignificantly simpler and more practical thanother existing methods found in several
literatures. The coconut shells were observed
to have the highest furfural yield among thechosen raw materials. The furfural yield was
also observed to have a general trend ofincreasing yield with increasing hydrolysis
time for all raw materials with coconut shells
being the most sensitive to the changes inhydrolysis time.

Standard Deviation
Raw Material

10 mins

15 mins

20 mins

Coconut Husk

0.77691.29710.7451

Coconut Shell

0.94440.7466

0.7783

Pineapple Bagasse

1.16750.656

0.4015

Water Hyacinth
1.8986
0.2778
Table 2. Average standard deviations.

1.3339Coconut shell gave the highest mass
yield with 7.21%, followed by coconut huskwith 5.55%, pineapple bagasse with 5.52%,
and finally water hyacinth with 3.64%. The
deviations in the values of the mass yields atthe same hydrolysis time may be attributed
to the fluctuations in the temperature of the- 10 -

Reference[1] Demirbas,

Ayhan.
“Furfural
Production from Fruit Shells by
Acid-Catalyzed Hydrolysis.” Energy
Sources, Pat A. (2006): 11.
[2] Kazemi, M., Zand-Monfared, M.R.,“Furfural Production from Pistachio
Green
Hulls
as
Agricultural
Residues.” Journal of Applied
Chemical Researches (2009): 19-24.
[3] Hitchcock, R.L., Froneberg, B.,“Commercial Production of Furfuralin its Twenty-fifth Year,” Chemical
Engineering Progress, 44 (1984):
669-674.

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Influence of tension during cure on tensile property of carbon nanotube
spun yarn reinforced epoxy
Kahori Oshima1, Yoshinobu Shimamura1, Keiichiro Tohgo1,
Tomoyuki Fujii1, and Yoku Inoue2
1

2

Department of Mechanical Engineering, Shizuoka University,
3-5-1 Johoku Naka-ku, Hamamatsu, 432-8011, Japan

Department of Electrical and Electronic Engineering, Shizuoka University

1. Introduction
Carbon nanotubes (CNTs) are expected
to exceed the mechanical properties of
conventional carbon fibers, but growing
continuous CNTs has limitation so far.
Consequently, it is difficult to apply CNTs tostructural components. In order to solve thismatter, spinning of CNTs has been
investigated, and continuous fibers of CNT
spun yarn can be fabricated easily [1]. In
addition, CNT composite made out of CNT
spun yarn are expected to be applicable tostructural components. However, the basic
mechanical properties of CNT spun yarn
reinforced composite have not been clarified.
In this study, CNT spun yarn reinforced
epoxy was fabricated by using the pultrusion
technique, and influence of tension duringcure on tensile property of CNT composite
was examined.

2. Materials
Multi walled carbon nanotube (MWNT)
spun yarn was used as reinforcement.
MWNT used in this study was grown on aquartz glass plate with chemical vapor
deposition using C2H2 and FeCl2 as a basematerial and a catalyst, respectively [1]. The
MWNT length was around 1 mm and thediameter was 50 nm. The spun yarn diameter
was about 45 m and the twist angle  was
between 27~35.
Bisphenol-A type room-temperature
curing epoxy (Bisphenol-A type) was usedas matrix of MWNT composite.

3. Fabrication of MWNT composite
MWNT composites were fabricated byusing the pultrusion technique. Figure 1
shows a schematic of pultrusion process of
MWNT composites. A die (120m) was- 11 -

made in a plastic plate for the pultrusion. A
MWNT bundle was dipped into resin andthen pultruded through the die. Then, a deadweight was attached to the bottom of thebundle while curing. Four different weightsfrom 10 g to 30 g were used in this study.

Fig.1 Pultrusion process of MWNT spunyarn reinforced composite

4. Influence of tension during cureTensile tests of MWNT composite wereconducted at room temperature. The crosshead speed was 1mm/min and the gauge
length was 15 mm. Strain was measured byusing a non-contact extensometer.
Figure 2 shows the relationship between
volume fraction of fiber and weight. The
volume fraction increased with increasing
weight. This is because resin in MWNT spunyarns was squeezed out by applying tensile
force.
Figure 3 shows tensile properties of
MWNT composite with the volume fractionof fiber. Young’s modulus and tensile
strength improved with increasing thevolume fraction. The maximum Young’s
modulus was 53 GPa, and the maximum
tensile strength was 485 MPa. The higher
tensile properties were probably brought bybetter load transfer to MWNT because of thehigh aspect ratio of MWNT.

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

6. Conclusions

Volume fraction Vf [%]40

1. The pultrusion technique of spun yarn was
effective in improving volume fraction andfiber orientation of MWNT composite.

30

20

2. Tensile properties of MWNT composite
were improved by tension during curebecause of the increase of volume fraction
and fiber orientation.

10

3. The fracture surface of MWNT composite
implies that fracture mode of MWNT
composite was fiber breakage.

0
0

10

20

30

40

Weight W [g]

500

100

400

80

300

60

200

40

100

20
B [MPa]

Reference
Young's modulus E [GPa]Tensile strength B [MPa]Fig.2 Volume fraction vs. weightE [GPa]

0
15

20

25

0
30

Volume fraction Vf [%]Fig.3 Tensile properties vs. volume
fraction

5. Fracture surface
Figure 4 shows a typical fracture surface
MWNT
composite(W=29.5g,
B=458MPa). MWNT pull-out length was
about 10 m while MWNT length was 1 mm.
The result implies that fracture mode of
MWNT composite was fiber breakage.
of

Fig.4 Fracture surface of composite(W=29.5g, B=458MPa)- 12 -[1] Y. Inoue, K. Kakihata, Y. Hirono, T.

Horie, A. Ishida, and H. Mimura,
APPLIED PHYSICS LETTERS, 92(2008), 213113

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Particle Size Distribution and Iron Loading of Iron Oxide-Coated Sand Sorbent
Jay R T. Adolacion*, and Maria Lourdes P. Dalida
Department of Chemical Engineering, College of Engineering, University of the Philippines,
Diliman, Quezon City, Philippines
TEL&FAX: +63-2-929-6640*
e-mail: jayr.adolacion@coe.upd.edu.ph

1. Introduction
Iron-oxide coated media has been usedas sorbents in the removal of various waterpollutants. These granular materials arecharacterized by an ensemble of different
particles sizes which may have varying
amounts of iron oxide coated unto it. In the
study of these particulate sorbents, one of theparameters affecting its sorption kinetics isthe sorbent dosage, which is the ratio
between the mass of sorbent and the amountof sorbate solution. In the absence of in-situ
methods for obtaining kinetic data, thealternative is to carry out ex-situ studies,
normally involving withdrawal of aliquots.
However, it will not be possible to maintain
constant sorbate dosage in the process. Thisin turn will influence the quality of the
kinetic data that can be obtained.
The problem is further compounded by
the effect of scale on the sorbate dosage.
Small-scale sorption studies are prone tovariability inherent in small granular sorbent
samples. In the case of iron oxide-coatedmedia, variability arises from variations inparticle size distribution, and possibly,
variations in the loading of iron-oxide
sorbent on the surface of the supporting
media (Fig. 1).
Thus, in order to quantify the effects ofaliquot withdrawal on kinetic measurements,
it is necessary to first determine the range ofsample sizes where variations in particle size
distribution and iron-oxide loading become
insensitive to sample size.
In this study, the variations in the particle
size distribution and iron loading werecompared across different quantities of ironoxide-coated sand (IOCS) samples. The ironloading was taken as a measure of theamount of iron oxide present on the IOCS
surface. The results were subjected tostatistical tests to determine any significant- 13 -

Fig. 1. SEM images of silica sand before(top) and after (bottom) coating with ironoxide. The rough surface after coating is due tothe iron-oxide deposited on the sand surface,concentrated mostly on cavities.

difference in the means and variances
between samples.

2. Particle Size Distribution
and Iron Loading Measurements
Pretreated white beach sand was coatedwith iron oxide using the method by Li et al.
[1]. Iron oxide sand samples were obtainedby tumble mixing prior to scoop sampling.
Image scans from several samples weretaken to obtain estimates for the populationand sample particle size distributions (Fig. 2).

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

References

Fig. 2. An image scan of iron oxide-coatedsand (IOCS). Millimeter marks are shown on
the lower left.

The particle size distributions were obtainedusing digital image analysis via ImageJsoftware [2]. IOCS samples were dissolvedin strong acid and the resulting solutions
were analyzed for their iron content using
HR-CS AAS.

3. Results and Discussion
The particle size distributions wereobserved to converge at higher sample
weights starting at 50-mg IOCS. The
variability in iron loading decreased withincreasing sample weight; however, larger
sample quantities were accompanied by theappearance of outliers. F-tests suggest thatvariances became insensitive to sample size
at 50 mg and above while T-tests suggestthat mean values seem to be the same at
25 mg and higher in both the particle size
distribution and iron loading measurements.
Translation of the results to particle countsuggests a minimum value 260 IOCS
particles to minimize variability attributable
to the granular nature of the IOCS. For
adsorption studies, it may be recommended
to fix the amount of adsorbent and vary thequantity of solution instead when using
small quantities of adsorbent.

4. Conclusion
Variability inherent in granular sorbents
may be lessened by using a sufficiently large
enough quantity of sample. Consequently,
variability in sorbent dosage can be
minimized by fixing the amount of sorbent
and adjusting the amount of the sorbate
solution instead in order to achieve thedesired dosage.

- 14 -[1] Li Dongmei, Huang Hui, Ye Tingjin,
Huang Mingzhu, Ren Yi, Liu Chunliu,
He Na, International Conference on
Computer Distributed Control andIntelligent Environmental Monitoring.
(2011) 1823-1826.
[2] WS Rasband, U. S. National Institutes of
Health. (1997-2011)

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Stress Analysis of Spun Yarn Reinforced Composites
Diyun Miao1, Yoshinobu Shimamura2, Keiichiro Togo2, and Tomoyuki Fujii2
1

Undergraduate Student, Shizuoka University, Japan
Department of Mechanical Engineering, Shizuoka University, Japan
1-7-29 Nunohashi, Naka-ku, Hamamatsu, Shizioka 432-8012, Japane-mail: dmiao@mechmat.eng.shizuoka.ac.jp

2

1. Introduction
Staple spun yarns are used as preform fornatural fiber reinforced composites for
decades. In addition, innovative techniques tomake spun yarn from carbon nanotubes haverecently emerged; this will enable us to makecarbon nanotube reinforced composites moreeasily. A spun yarn has very complex
geometry of staple fibers such as twist,
migration and discontinuity. The complexity
gives rise to difficulty for analyzing staple
spun yarn. Thus, analyzing staple spun yarn
reinforced composites is a challenge but
necessary for developing the new types ofcomposite materials.

The following assumptions are adopted
in this study:
・axially symmetric deformation,
・no torsion around the z-axis, and・uniform strain along the z-axis direction.
,Thus, displacements in the
directions are expressed as
,
0,

2.1

and
(1)

Strain-displacement relations

Substituting Eq.(1) into generalizedstrain-displacement relations for a cylindricalcoordinates gives the following equations.

2. Stress analysis
by using theory of elasticity，

A model shown in Fig.1 is used to analyze
staple spun yarn reinforced composites.
Displacements in of the,anddirections are represented as ,and ,respectively.

1

，
，
0

2.2

(2)

Constitutive equation

A coordinate system 12’3’ shown in
Fig.1(c) is defined as a material coordinate
system. Filaments are aligned in the 3’ axis.
The compliance matrix C’ in the material
coordinate system is written as000
1/ ET TT / ET LT / EL



1
/
/
0
0
0
E
E


T
LT
L




1/ EL
0
0
0
C'  

1
/
0
0
G
LT




1/ GLT0Sym.

2(1TT) / ET (3)(a) Helical reinforcement, (b) An element incomposite, (c) Definition of coordinates
Fig.1 Microelement in a cylindrical coordinate
system.

- 15 -， ，
andcan be calculated byusing the rule of mixture and the shear-lag
model.

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Relationships between stress and strain
components in the reference and material
coordinate systems are described as
∙ ，
∙
(4)
and
are rotation matrices.
where
By using the Eq.(4), a stiffness matrix
isexpressed as′∙(5)
In this case,
0，
0
(6)
but
is not always zero in order topresent torsion around the z-axis.

2.3

Equilibrium equations

2.4

2

(11)

3.

(7)

Governing equation

Young's modulus of jute fiber-reinforced
polymer with a twisting angle α is calculated
by using the mathematical model. The
physical properties of a jute fiber-reinforced
polymer are shown in Table1.

14
12

8
6
4
2

Young's modulus of staple
spun yarn reinforced
composites

00Young's modulus of a staple spun yarn
reinforced composite can be calculated asfollows.
At first, the total force P in the z-axis
direction is∙∙10
Eyarn[GPa](8)
The differential equation of Eq.(8) can besolved under the following boundary
conditions.
0
(9)
0
0，

2

Jute
6.0×10-5
6.0×10-4
45
27.4
0.8
0.3
0.3

Figure 3 shows Young's modulus of jutefiber-reinforced composites as a function of
the twisting angle α.
0∙

ExampleMaterial
Radius of fiber [m]Length of fiber [m]Volume fraction of fiber [%]Young's modulus of fiber [GPa]Young's modulus of resin [GPa]Poisson's ratio of fiber [-]Poisson's ratio of resin [-]From Eqs.(2), (5) and (7), thegoverning equation is derived.

2.5

，

∙

Table1 Physical properties

Force equilibriums in theanddirections always hold from Eq.(6). The
force equilibrium in the direction isexpressed as
0Then, the average stress and Young's
modulus of the composite are given as(10)- 16 -

5

10 15 20 25 30 35 40 45
Fig.3 Young's modulus of Jute spun yarn
reinforced composite.

4. Conclusions
An analytical method for spun yarn
reinforced composites based on the theory ofelasticity was proposed and an example wasdemonstrated.

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Comparison of Various Dip-Coated and Spray-Coated TiO2 Catalysts
for Photocatalytic Reactor Applications
Patrick D. Ramoso*, Maria Lourdes P. Dalida
Department of Chemical Engineering, College of Engineering, University of the Philippines,
Diliman, Quezon City 1101, Philippines
TEL&FAX: +63-2-929-6640*
e-mail: pdramoso@up.edu.ph

1. Introduction
Pollution from industrial effluents
continues to be a threat to our water supplies.
With this, the challenge of developing anefficient wastewater treatment process has
been studied in the past years. Photocatalysis
has been extensively studied for its ability tocompletely mineralize organic and inorganic
contaminants from water [1]. Many organic
pollutants in water can be completely
decomposed at the surface of UV-irradiated
TiO2; these include alkanes, haloalkanes,
aliphatic alcohols, carboxylic acids, alkenes,
aromatics,
haloaromatics,
polymers,
surfactants, herbicides, pesticides and dyes
[2].
The photocatalytic reaction is initiated by
the excitation of TiO2 by UV light havingenergies greater than or equal to the band
gap energy, resulting to the generation ofmobile electrons and positive holes. This
starts a chain of reactions leading to thecomplete mineralization of organics tocarbon dioxide and water. The photocatalyst
could either be suspended in a slurry or
immobilized on a support. Slurry systems
require a post-process separation such as
filtration to separate the catalyst. In an
immobilized system, the operation iscontinuous and it does not need any
additional separation process. However, it
may be vulnerable to catalyst wash out [3].
In this study, Degussa P25 TiO2
photocatalyst was immobilized on glass
using various coating methods. The
supported catalysts were subjected toscanning electron microscopy (SEM) for
surface characterization.

2. Experimental
Degussa P25 TiO2 (25% rutile, 75%- 17 -

anatase) was used as the photocatalyst to becoated on glass. Two glass materials wereused to support the catalyst: 1) glass Raschigrings approximately ¼ inch in diameter; 2)
modified tubular reactor of approximately 12
inches in length. Various coating methods
listed in Table 1 were used to immobilize theTiO2.
Table 1. Coating methods

Method Description
1
TiO2-water slurry on Raschig ringsby dip-coating
2
TiO2-ethanol slurry on Raschigrings by spray-coating
3
TiO2-ethanol slurry on tubular
reactor by air-assisted spraycoating
The first method discussed in Table 1
served as reference to a previous study on
TiO2 coating on glass Raschig rings [4]. For
method 2, the dip-coating method was
replaced by spray coating using an atomizer.
Method 3 used compressed air to coat thecatalyst on a modified glass tubular reactor.
The glass-supported catalysts wereallowed to stand and dry for 24 hours, andwere calcined afterwards at 573 K. SEM
images of the calcined catalyst wereobtained using a Hitachi S-3400N scanningelectron microscope.

3. Results and Discussion
Figures 1 to 3 show the resulting SEM
images of the calcined catalysts preparedusing methods 1 to 3, respectively.
The dip-coated TiO2-water slurry on
glass Raschig rings in Figure 1 shows a nonuniform dispersion of the catalyst on theglass surface. Aside from this, multiple
layers of TiO2 are observed; this is not aProceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

desired characteristic of immobilizedcatalysts due to unutilized catalyst surface.
The spray-coated TiO2-ethanol slurry on
glass Raschig rings as shown in Figure 2
indicates complete surface coverage of theglass surface with TiO2. The layering of
catalyst is relatively even, but the problem ofmultilayer coating is still quite evident.
The air-assisted spray coating of TiO2ethanol slurry on a glass tubular reactor, seenin Figure 3, shows complete surface
coverage with a less degree of multilayer
coating. This may have been caused by thecompressed air, which could have improved
the dispersion of the TiO2-ethanol slurry as itis sprayed onto the glass surface. The lengthof the tubular reactor may have also
contributed to a more even coating since any
excess slurry would just flow to adjacentareas within the reactor, in contrast to spraycoating on glass rings, at which the slurrytends to accumulate on the glass rings,
causing multilayer coating.

Fig. 3. SEM image of TiO2 spray-coated on glass
tubular reactor

4. Conclusion
Air-assisted spray coating on long glass
tubular reactors provided the most uniform
dispersion of TiO2 photocatalyst among thevarious methods tested. It is recommended toproceed with this method in performing
actual runs to mineralize organic substances.

Acknowledgments
The authors thank Angella Rainbow
Lim, Karmina Grace Bautista and Riuji Satofor the fabrication and TiO2-spray coating of
the tubular photocatalytic reactor, andAdolph Bravo Jr., Ervin Cezar and Darlene
Que for the preparation of TiO2-coatedRaschig rings.

References
Fig. 1. SEM image of TiO2 dip-coated on glass
Raschig rings

Fig. 2. SEM image of TiO2 spray-coated on glass
Raschig rings- 18 -[1] K. Nagaveni, G. Sivalingam, M.S. Hegde
and G. Madras, Appl. Catal. B. Environ.
Lett. 48 (2004) 83-93.
[2] A. Fujishima, X. Zhang and D.A. Tryk,
Surf. Sci. Rep. 63 (2008) 515-582.
[3] H. de Lasa, B. Serrano and M. Salaices,
2005. Photocatlytic Reaction
Engineering. USA: SpringerLink.
[4] P. Ramoso, M.P. Dalida. (2011). Dip
coating of TiO2 photocatalyst on glassraschig rings for flow photocatalytic
reactor application. Presented in: JapanPhilippine Joint Workshop on Materials
for Safe and Sustainable Society 2011.
Hamamatsu, Japan.

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Diffusion of Inroganic Acids in Epoxy and Polyurethane Thermosetting Resins
Jonas Karl Christopher N. Agutayaa*, Zarlon M. Bernardoa, Lorenz Anthony T. Fernandoa,
Timothy David T. Salmoa, Terence P. TumolvaaaDepartment of Chemical Engineering
University of the Philippines, Diliman, Quezon City 1101 Philippines
TEL&FAX: +632-929-6640
Email: jnagutaya@gmail.com
1. Introduction

From the stock solutions purchased fromlocal suppliers, 5M solutions of sulfuric acid,nitric acid, and hydrochloric acid wereprepared.

Chemical recycling is the conversion ofwaste polymers into feedstock or fuels (Lin &Yang, 2009). Various efforts of plastics
recycling were made in the past decade.
However, recycling of thermosets like epoxies
and polyurethane displays a unique problem
due to its network structure of cross-linking
chains.
Epoxies commonly used today are
digycidyl ether of bisphenol-A (DGEBA),
which is a product between ephicholrohydrin
and bisphenol A (Anon., n.d.). These epoxies
are commonly used in manufacturing coatings,
adhesives and glass fiber reinforced plastics(GFRP).
On the other hand, polyurethane is a
product of a reaction between a diisocyanate
and a polyol. The common uses ofpolyurethanes are in the manufacturing of
rigid foams used in refrigeration and roof andwall insulations, coatings, and other sports
equipment and furniture.
Most applications of these thermosets arefor long-term purposes due to their crosslinked chains, which give durability. However,the cross-linked chains also make it difficult
for this type of plastic to be recycled.
In this study, the rate of diffusion – as aprecursor to dissolution – of inorganic acid in
epoxy and polyurethane was compared
qualitatively. The acids used were H2SO4,
HNO3 and HCl, and the temperatures were
30°C, 50°C, and 80°C.

2.2. Decomposition experiments
Each specimen was immersed in 150 mLof a particular acid in a beaker. Each beaker
was then placed in oil baths at 30°C, 50°C, and80°C. Three sets of five specimens wereprepared for each acid at a particulartemperature.
Over a period of 12 days, samples wereperiodically taken out of the beaker and were
weighed using an analytical balance. The
percentage of weight loss was then plottedagainst the square root of time. Plateau points
were identified.
3. Results and Discussions
3.1. Change in weight of epoxy resin
Figure 1 shows that the mass of the epoxy
resin increased continuously at 30°C for all theacids. At this temperature, the diffusion
process was more prevalent than the reactionof the acid with the epoxy.
In the case of the immersion of epoxy in
HCl and H2SO4 solutions at 50°C, the same
trend of increasing mass was also apparent.
However, in the case where HNO3 was used as
the acid, a more abrupt increase in mass of theresin occurred after 36 hours. After 210 hours,
the mass of the continuously decreased until
the resin dissolved completely.
The trends at 50°C can also be observed at
80°C. However, the reaction between HNO3
and epoxy at this temperature is moreprevalent than at 50°C as evidenced by anactual decrease in weight of the epoxy resinwith respect to its original mass. The resin
completely dissolved in the acid after 72 hours.

2. Methodology
2.1. Preparation of Resins and Acids
Epoxy and polyurethane thermosetting
resins were purchased from Polymer Products
Philippines, Inc. Both polymers were moulded
into 2 cm × 4 cm × 2 mm sheets. Each sheet
was weighed prior to immersion in acid.

- 19 -

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

the resin dissolves into the solution. The data
gathered for the PU resin submerged in HNO3
is limited for 12 hours since beyond that point,
the resin is very brittle, hence, very difficult tosubject to analysis.

3.5% weight change

3
2.5
2

1.5
1

4. Conclusion

0.5
0
0

200

400
600
800
1000
square root of time (√s)

1200

For the epoxy resin, nitric acid diffuses thefastest, followed by sulfuric acid, thenhydrochloric acid. On the other hand, nitricacid diffuses in polyurethane the fastest,
followed by hydrochloric acid, and lastly,
sulfuric acid.
Furthermore, an increase in temperature
improves the diffusion in both polymers for all
the acids.

Figure 1. Percentage weight gain of epoxy resin
vs. square root of time at 30°C.

3.2. Change in weight of polyurethane
resin
The mass of the polyurethane resin at
30°C increased then stabilized (Figure 2).
There was a more rapid increase in the weightof the polyurethane resin as compared to theepoxy. This is mainly due to a porous structure(Forrest, 1999) of the polyurethane. Also, thepercent change of the PU resin in HNO3 isthrice as much as compared to the resinssubmerged in the H2SO4 and HCl. The
increase in weight of the resin in HNO3 is
attributed to the formation of a tertiary amine
salt group upon reaction (Abacha, et al., 2009).

% weight change

400

References
Journals
1. N. Abacha, M. Kubouchi, T. Sakai, K.
Tsuda (2009). Diffusion behavior of waterand sulfuric acid in epoxy/organoclay
nanocomposites. Journal of Applied
Polymer Science, 112: 1021-1029.
2. G. Behrendt, B. W. Naber (2009). The
chemical recycling of polyurethanes(review). Journal of the University ofChemical Technology and Metallurgy, 44:
3-23.
3. Y.-H. Lin, M.-H. Yang (2009). Kinetic
and mechanistic modeling of acidcatalyzed degradation of polymers withvarios cracking catalysts. Journal ofApplied Polymer Science. 114: 2591-2599.
Book and book chapter
1. M.
Forrest(1999).
ChemicalCharacterisation of Polyurethanes, United
Kingdom: Rapra Technology Ltd..
Internet
1. Anon. (n.d.). Chemistry of Epoxies /Epoxy Resin, Novolacs. Available fromhttp://www.epoxyproducts.com/chemistry.
html. Accessed August 2011.

sulfuric acidnitric acidhydrochloric acid

300
200
100
0
0

500
1000
square root of time (√s)

Figure 4. Percentage weight gain ofpolyurethane resin vs. square root of time at
30°C.

The previous trend in HNO3 also
manifested at 50°C. At this temperature, theHCl also exhibited the trend similar to HNO3.
The percent change in weight for both acids
was close to 300%. This observation isconsistent according to the general reaction ofpolyurethane resin with an inorganic acid,
which produces amine salt (Behrendt & Naber,2009). However, after 156 hours, the PU resin
in HNO3 and HCl significantly decreased in
mass.
The
trend
for
the
previous
temperatures was the same for 80°C. Resincontinued to increase in weight due to theformation of the amine salts. After 156 hours,- 20 -

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Upgrading functionalities of Ultrasonic Torsion Fatigue Testing Machine
Akito KOKUBO1*, Yoshinobu SHIMAMURA1, Hiroki MASUDA1,
Hitoshi ISHII2 , Keiichiro TOHGO1, Tomoyuki FUJII1, Tooru YAGASAKI3
and Masamichi HARADA3
1

Department of Mechanical Engineering, Shizuoka University
3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 432-8561, Japan
2
Professor Emeritus, Shizuoka University
3
Honda R&D Co., Ltd*e-mail: akokubo@mechmat.eng.shizuoka.ac.jp

1. Introduction
Recently, fatigue failure due to gigacycle
loading (more than 107 cycles) has beenreported. It is necessary to investigate
gigacycle fatigue. However, the loading
frequencies of conventional fatigue testingmachines are around 20Hz. It takes 19months to achieve gigacycle if the frequency
is 20 Hz.
For reducing the testing time, we havedeveloped an ultrasonic torsional fatigue
testing machine. The cyclic frequency of thetesting machine is around 20 kHz. It takes
only 14 hours to achieve gigacycle and thismachine enables us to accelerate fatigue
testing considerably. In this study, wedeveloped a new ultrasonic torsion fatigue
testing machine in order to solve difficultiesof the existing testing machine. In addition,
fatigue tests were conducted by using the
new testing machine to confirm theperformance.

cyclic loading can be applied to thespecimen due to resonation. Since thetorsional displacement generated by theoscillator is small, the torsional displacement
is amplified by decreasing the sectional areasof horn and specimen.

2.2 Features of new testing machine
New testing machine adopts a signal
generator that can automatically tune theresonance frequency and can be controlled
through external input; fatigue tests can becontrolled by using a PC.
In an existing testing machine, torsional
displacement amplitude depend on mass ofa specimen. On the other hand, in the new
testing machine, displacement amplitude wasalmost constant regardless of specimen’smass because we adopted a well-tuned
amplifier.

2. New Ultrasonic Torsion Fatigue
Testing Machine

Torsional
Oscillator

2.1 Ultrasonic torsion fatigue testingmachineMounting
part

AmplifierConfiguration of an ultrasonic torsion
fatigue testing machine is shown in Fig.1.
The main components of the ultrasonictorsion fatigue testing machine are a signal
generator, a torsional oscillator, anamplifying horn and a specimen. A signal
generator generates electronic signal at theresonance frequency of the horn andspecimen. Torsional oscillator converts theelectronic
signalintoatorsional
displacement at the same frequency. Thus

- 21 -

Signal generator

PC

Amplifying
horn
Laser disp.
sensorSpecimen

Microscope

Torsion disp.
measurement

Fig. 1 Ultrasonic torsion fatigue testing machine.

3. Material and specimen
Alloy steel (SCM420H) was used in thisstudy. The shape and shear stress distribution
in a specimen are presented in Fig.2.
Specimen was annealed, quenched and thentempered. The conditions of the heat
treatment are presented in Table.1.
Shear stress
Torsion displacement

71

300

200


100
106

107

108

109

1010

Number of cycles N (cycle)

R 86.1

20

Shear stress amplotude max (MPa)Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

O 7

O 10

Fig. 3 S-N diagram.

(a) Specimen shape (b) Shear stress distribution
Fig. 2 Specimen.

Table 1 Heat treatment condition.

Fig. 4 Fatigue crack (Nf=1.4×108)

4. Fatigue tests
Ultrasonic torsion fatigue tests wereconducted for the specimens. The stress ratio
R was -1, and loading frequency was about
20 kHz. When the reduction of the resonancefrequency was more than 30Hz, fatigue tests
were interrupted. Since heat generation was
remarkable during test, intermittent loadingwere set to suppress temperature increase
within an allowable range (i.e. less than
100°C in the case of steel). The maximum
shear stress was estimated from a torsional
displacement at the end of a specimen using
a relationship between them obtained by
FEM analysis. The torsional displacement
was measured using a microscope during
fatigue testing.
An S-N diagram was plotted in Fig. 3. The
fatigue strength at 109 cycles was about
170MPa. The surface of a failed specimen at
1.4×108 cycles was observed. A star shaped
crack was found as shown in Fig.4.

- 22 -

5. Conclusions
A new ultrasonic torsion fatigue testingmachine was developed and fatigue tests byusing this testing machine were conducted.
Fatigue strength at 109 cycles of quenched
and tempered SCM420H was about 170MPa.
A star shaped fatigue crack was observed forthe failed specimen.

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

A Degradation Study for the Acid Recycling of Polyurethane andPolyfurfuryl Alcohol Resins
Ronald P. Bual1,2, Terence P. Tumolva1
1Department of Chemical Engineering, University of the Philippines – Diliman Quezon City 1101 Philippines,2Department ofChemical Eng’g. & Tech., MSU-Iligan Institute of Technology, Iligan City 9200 Philippines,
1e-mail: rpb0853@gmail.com

1. Introduction

2. Methodology

Concern for the environment, both in terms oflimiting the use of finite resources and the needto manage waste disposal, has led to increasingpressure to recycle waste materials. Ever since
the first industrial scale production of synthetic
polymers
took place,the production,
consumption and waste generation rate of plastic
has increased significantly. Thus, recycling ofplastic wastes has been a focus of many
researches in the past few decades.

2.1. Materials and sample preparation
PU resin was purchased from Polymer Products
Philippines, Inc. in set A & B. The components
were mixed in a 1:1 ratio. Then it was allowed toharden in personally designed plastic containers
for hours and was cut into 2cm x 4cm x 2mm.
Meanwhile, PFA resin was provided by Hitachi
Chemical Co., Ltd., cured and was cut into thedesired dimension. Then the weights of thesamples were taken before immersing them into
the acids.

Enormous efforts have been launched in thefield of disposal of plastic wastes in recent years,
especially thermosetting resin that is difficult torecycle due to its network structure of crosslinking chains. Chemical recycling is a new andpromising technique for converting plastic
wastes by returning them back to its original
constituents, that is, monomers or petrochemical
feedstock, and has received a great deal ofattention in recent years [1].

2.2 Degradation Experiment
Eighteen beakers were used for the set-up; each
was filled with 150 mL of acids. The samples
were then submerged into the acids, with the top
part of the sample hanging into modified clips.
The beakers were then sealed with plastic wrap,
and placed according to their maintaining
temperature. Thermostat waterbaths, that werepurchased from BE Scientific Glass Instruments,
were used to maintain the three temperatures.

In this study, the chemical recycling of twothermosetting
resinswasconducted;
polyurethane (PU) and polyfurfuryl alcohol(PFA) resins. This study will further investigate
the effect of two parameters in the degradationof the resins. These parameters are the type ofstrong inorganic acids (HCl, H2SO4, HNO3) usedas the solvent and the immersion temperature.
The study will be extended to the diffusion ofacid in polyurethane resin as well. The diffusion
reaction mechanisms were studied given varying
temperature with the goal to establish parametricdata that will help further researches on
chemical recycling.

2.3 Weighing
After a certain time interval, mostly at a six hour
period, samples were taken out of the beaker,
then dampened into tissue papers and were
weighed using an analytical balance.
2.4 Analytical Methods
From the mass weighing data, percent weightchange versus square root of time was plotted toinvestigate the effect of the parametersconsidered. FT-IR will be used to analyze
chemical reactions. GCMS, DSC, SEM will also
be used to characterize the virgin and recycledresin.

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Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

3. Results and Discussion

Figure 4. Percentage weight change of PFA vs.
square root of time in nitric acid at various
temperatures.

Figure 1. Percentage weight change of PU vs. squareroot of time at 30 °C in three different acids.

The mass of the PU resin at 30 °C increases thenstabilizes. This trend proves that the mass of theresin is already close to its maximum weight.
The effect of temperature is seen in Figure 2
with the percent weight change of PU resin
increased as high as 600% and decreased
continuously at 80 °C. This shows that diffusionand degradation proceeds at a faster rate when
the temperature is high.
In Figure 3 and Figure 4, the degradation of PFA
resin is faster with nitric acid than the otheracids.

Figure 2. Percentage weight change of PU vs. squareroot of time in hydrochloric acid at various
temperatures.

4. Conclusion

Figure 1 and Figure 3 shows the effect of thethree strong inorganic acids to polyurethane andpolyfurfuryl alcohol at 30 °C. While Figure 3
and Figure 4 shows the effect of three different
temperatures in hydrochloric acid. It can be
implied from the trends that diffusion is moreprevalent in the reaction of the PU resin than thereaction of the PFA resin with the acid.

The change of weight (%) of the thermoset resin
is proportional to temperature and varies greatly
with the type of inorganic acid used.
Diffusion of the acid takes place first for PU,
followed by the side reactions which further
increase the weight of the resin, then followedby the breakage of the polyurethane group.
While the degradation of PFA resin proceeds via
breakage of the cross-linking bond.
It could be said that among the three acids HNO3
is the fastest to diffuse and degrade the polymer.
And among the three temperatures, 80°C makes
the reaction proceed fast as compared to the two.
Reference[1] Dang, W., Kubouchi, M., Sembokuya, H., &Tsuda, K. (2005). Chemical recycling of glass
fiber reinforced epoxy resin cured with amine.
Polymer 46 , 1905–1912.

Figure 3. Percentage weight change of PFA vs.
square root of time at 30 °C in three different acids.

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Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Effect of Specimen Size on the Gigacycle Torsion Fatigue Properties
Takanori IZUMIKAWA1*, Yoshinobu SHIMAMURA1, Hiroki MASUDA1,
Hitoshi ISHII2 , Keiichiro TOHGO1, Tomoyuki FUJII1, Tooru YAGASAKI3
and Masamichi HARADA3
1

Department of Mechanical Engineering, Shizuoka University
3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 432-8561, Japan
2
Professor Emeritus, Shizuoka University
3
Honda R&D Co., Ltd*
E-mail: tizumikawa@mechmat.eng.shizuoka.ac.jp

1. Introduction
Recently, fatigue failure due to gigacycle
loading (more than 107 cycles) has beenreported. It is necessary to investigate
gigacycle fatigue. Since the loading
frequencies of conventional fatigue testingmachines are around 20Hz, it takes 19months to achieve gigacycle. Therefore,
developing a new method that can accelerate
fatigue testing is required, and ultrasonictorsional fatigue testing machines have beendeveloped. The cyclic frequencies ofultrasonic testing machines are around 20
kHz. It takes only 14 hours to achieve
gigacycle and it is possible to reduce fatigue
testing time considerably. However, researchon the frequency effect and size effect on
fatigue life is limited. In general, fatigue
strength obtained by ultrasonic torsion
fatigue testing are higher than that ofconventional methods.
In this study, fatigue testing was
conducted for two types of specimens withdifferent risk volumes by using an ultrasonictorsion fatigue testing machine, and theeffect of specimen size on gigacycle torsion
fatigue property of high strength steel wasinvestigated.

2. Ultrasonic Torsion Fatigue Testing
Machine
The configuration of an ultrasonictorsion fatigue testing machine used in thisstudy is shown in Fig.1. The main
components of the ultrasonic torsion fatigue
testing machine are a signal generator, atorsional oscillator, an amplifying horn and a
specimen. A signal generator gives electronic
signal at the resonance frequency of the horn- 25 -and specimen. Torsional oscillator converts
the electronic signal into a torsional
displacement at the same frequency. Thus
cyclic loading can be applied to thespecimen due to resonation. Since thetorsional displacement generated by theoscillator is small, the torsional displacement
is amplified by decreasing the sectional areasof horn and specimen.

Torsional
Oscillator
Mounting
part

Signal generator
PC

Amplifyinghorn

Specimen

Laser disp.
sensorMicroscope

Torsion disp.
measurement

Fig. 1 Ultrasonic torsion fatigue testing machine.

3. Size effect and frequency effect
The size effect on torsion fatigue
properties using conventional and ultrasonictorsion fatigue testing machines was studied
by Sakanaka [1]. Figure 2 shows the result.
Open diamonds are torsion fatigue testing
results of large specimens with 318.9mm3risk volume. Open circles are torsion fatigue
testing results of small specimens with
3.570mm3 risk volume, and solid circles are
results of small specimens with 3.126mm3
risk volume by using ultrasonic torsion

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

fatigue testing. As shown in Fig.2, the riskvolume has significant effect on the fatigue
strength as well as frequency. This is called
size effect. Size effect is brought fromincrease of the existence probability ofcritical defects such as non-metal inclusions.

5. Conclusion
Two types of specimens with different riskvolumes were designed successfully and are
now under fatigue testing.

Reference[1] N. Sakanaka, Y. Matsubara, Proceedingsof JAST Tribology Conference, 2012,257-258.

Fig. 2 S-N diagrams obtained by torsional
fatigue tests [1]4. Design of specimens
Two types of specimens with a large riskvolume and a small risk volume were
designed. Basic dimensions were determinedby using a theoretical formula, but FEM
analysis was also performed to tune thetorsion resonance frequency (20kHz). Figure
3 shows dimensions of specimens and shear
stress distributions. An Hourglass shapespecimen shown in Fig.3 (a) has a small riskvolume of 4.88mm3 because shear stress
distribution profile is sharp. On the other
hand, a half dumbbell shape specimen shownin Fig.3 (b) has a large risk volume of
56.5mm3 (11.6 times greater than that of thehourglass shape specimen) because shear
stress distribution profile is moderate.

Fig. 3 Dimensions of specimens and shear
stress distribution. .

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Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Lifetime Prediction of Furan Resin using Thermal Analysis
Jhud Mikhail O. Aberillaa*, Terence P. Tumolvaa, and Masatoshi KubouchibaDepartment of Chemical Engineering
University of the Philippines, Diliman, Quezon City 1101 Philippinesb
Department of Chemical Engineering
Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552 Japan*
Corresponding Author’s E-mail: joaberilla@up.edu.ph

1. Introduction

2. Theory

At present, there is already a greatabundance of research on natural fiber
reinforced polymeric (NFRP) compositesmostly on the evaluation and improvementof mechanical performance when using
non-biodegradable composite matrices suchas thermosetting resins. However, limited
data is available to gauge the environmental
advantages of these materials- in particular,
the carbon storage potential with the use ofrenewable bio-based materials. Since CO2
fixation capacity is the key environmental
parameter evaluated in this study, certain
LCA principles are applied on the material toserve as a guide and tool for the evaluationof carbon storage potential. For long-term
CO2 fixation, the bio-based carbon content
of a material is just one of the parametersthat must be determined in order to evaluate
overall carbon storage potential- anotherparameter that must be considered is the
lifetime of the material.
Due to the long lifetime of highly stablefuran (>102 years), it is definitely not
feasible to simply wait and directly measure
the longevity of carbon fixation of the resin
and its composites; therefore, a different
approach is necessary. One popularly known
method of predicting lifetime of polymericmaterials is by thermogravimetric analysis(TGA). In this study, TGA is performed toevaluate the thermal decomposition of furan
by measuring the weight loss at a fixedheating rate, and the parameters of thedegradation kinetics are obtained to establish
lifetime.

Methodological problems associatedwith kinetic analysis of polymer degradationand stability have been well discussed inliterature [2]. Both theoretical assumptions
and experimental conditions are known toaffect the reliability of obtained values for
activationenergy.
In
thisstudy,
thermogravimetric analysis under multiple
heating rates reduces statistical ambiguity
associated with the kinetic model assumed.
Isoconversional methods, both model-free
and integral [2] will be used to assess thecomputational variation of the calculated
activation energies.

- 27 -

3. Results and Discussion
Using data from thermogravimetricanalysis (TGA), various linearized forms of
the kinetic equation can be fit using linear
regression. For the model-free method, twoapproximations [1, 3] are used for thetemperature integral.
The forms of integral isoconversional
methods are derived from the integrated
form of the rate equation. Since this equation
does not have an analytical solution,
approximations are used on the generalized
linear form: i 
 E 
ln  B   Const  C T  RT   ,i 

The built-in function fminsearch() of
MATLAB (version R2010b) is used to locate
the minimum function value.
The activation energies calculated ateach conversion value are plotted in Figure 1.
Initial inspection of the graph indicates that
there is a consistent trend showing thevariation of activation energy withconversion. The initial mass loss (α < 0.20)

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

with higher activation energy is attributed toevaporation of volatile material. In the rangeof 20-80% degradation, the Eα values may beconsidered to vary with minor significancewith respect to α, as the difference between
the maximum and minimum within the range
is less than 30% of the mean value [4]. This
indicates that a single mechanism isfollowed through the most part of the resin
decomposition.

Fig. 1 Variation of E with respect to conversion( ○Flynn-Wall-Ozawa, □KissingerAkahira-Sunose, Δ Starink, × Vyazovkin[Agrawal approx.], * Vyazovkin [Cai approx.])

Except for the Ozawa-Flynn-Wallmethod, the choice of temperature integral
approximation
affects
theresultingcalculations minimally; based on the results,
there is a strong agreement between all theother methods, which suggests that theactivation energy for the degradation offuran resin is approximately 88 kJ/mol(Table 1).
Table 1. Determination of Activation Energy
Calculated E
Method(kJ/mol)
Ozawa-Flynn-Wall
95.4178
Kissinger-Akahira-Sunose
87.7722
Starink
88.2044
Vyazovkin (Agrawal approx.)88.5013
Vyazovkin (Cai approx.)88.4998

be expressed as:t g ( )
A exp(  E / RT0 )to determine the time expected to reach agiven conversion at a constant temperature
T0. Mass loss is taken to be the criteria ofdegradation, with 5% loss (α = 0.05) as thelimit for usefulness. The predicted useful lifeof the resin at different temperature
conditions is shown in Figure 2.

Fig.2 Predicted Useful Lifetime of Synthesized
Furan Resin

4. ConclusionA
comparison
ofVyazovkin’s
isoconversional method with integral
methods yielded similar values of theactivation energy for the decomposition
reaction. It is recommended for future workthat complete confirmation of the kinetic
triplet be concluded by verifying the reaction
mechanism. Other optimization methods canalso be used on the TGA data to affirm theaccuracy of the kinetic triplet. Aside frommass loss as criteria, further study caninvestigate the relevant physical andchemical properties as functions of the resin
degradation to create the full criteria for
useful lifetime.

References
The method of invariant parameters isused to obtain a model-free prediction for the
pre-exponential factor. A form based on the
Cotes-Redfern method [2] is applied withselected kinetic models of decomposition forthe compensation effect [4].
For lifetime prediction, a phaseboundary reaction model is expected for thesystem as the geometry and mechanism ofexperimentation provides such conditions.
Since a single-step process can be assumed
for the degradation, the kinetic equation can- 28 -[1] R.K. Agrawal, M.S. Sivasubramanian(1987). AIChE Journal 33: 1212-1214.
[2] P.
Budrugeac(2005).
Polymer
Degradation and Stability 89: 265-273.
[3] J. Cai, F. Yao, W. Yi, F. He (2006).
AIChE Journal 52: 1554-1557.
[4] S.
Vyazovkin,etal.
(2011).
Thermochimica Acta 520: 1-19.

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Investigation of damage behavior
in paper-based friction materials under compressive loading
Naoya URATA, Tomoyuki FUJII, Keiichiro TOHGO and Yoshinobu SHIMAMURA

Department of Mechanical Engineering, Shizuoka University,
3-5-1 Johoku, Naka-ku, Hamamatu, Shizuoka, 432-8561, Japane-mail: nurata@mechmat.eng.shizuoka.ac.jp
1. Introduction
Paper-based friction materials are usedforclutchdiscs
ofautomatictransmission. Performance and reliabilityof automatic transmission depend on
mechanical properties of paper-based
friction materials. Cyclic compression
tests as conventional tests have been
conducted in order to evaluate fatigue
strength of paper-based materials. Figure
1 shows the thickness reduction of thepaper-based materials composed ofaramid fiber or cellulose fiber as areinforcement as a function of number ofcycles from the results of theconventional tests. The tests wereconducted under cyclic load with the
maximum compressive stress of 60MPaand stress ratio of 0. The thickness ofboth materials deceases with increasing
the number of cycles. The aramid-basedand cellulose-based material are broken
at around 106 and 105 cycles, respectively.
The fatigue life of the cellulose-based
friction material is shorter than that ofaramid based friction material. Thesefatigue properties are attributed todeformation and damage in internal
microstructure, such as fiber and resin.
However, the deformation and damage
behaviorofpaper-based
frictionmaterials have not been clarified .
This paper deals with the deformationand damage behavior of paper-based
friction materials under the cyclic
compressive loading. The influence ofcompressive stresses on damage
behavior in internal microstructure wasFig.1 Reduction of thickness conventional compression
test as a function of number of cycles- 29 -

examined.
2.Experiment
2.1 Material and specimen
The materials used are aramid-basedand cellulose-based friction materials.
The aramid-based and cellulose-basedmaterial are composed of aramid fiberand phenolic resin, and cellulose fiberand phenolic resin, respectively. The
both materials include the fiber of
70wt% and phenolic resin of 30wt%. The
thickness of both materials is 1.1 ±0.1mm.
The materials were cut into squareshape with 10mm on a side. Preliminarily,
the precise cross-section was formed by
the cross-section polishing machine(CP)in order to observe the cross-section by ascanning election microscope(SEM) .
2.2 Cyclic compressive test
The cyclic compressive tests werecarried out in order to investigate theinfluence of compressive stress on thedamage behavior in the paper-based
friction materials. The tests were carriedout under the pure compressive cyclic
stress with the stress ratio of 0.1 andapplied load rate of 0.1kN/min. The
maximum stress increased stepwise up to
100MPa. The compressive cyclic load
was repeated five times. After the fifth
cycle at same stress level, thecross-section was observed by using
SEM and the deformation and damage
behavior
inmicrostructurewasinvestigated. Figure 2 shows theobservation area on the cross-section of
the cellulose-based material. The 12
areas in the cross-section were observedby using SEM. Three specimens were

200μm

Fig.2 Observation area during compressive test.

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

prepared for each of materials.
3. Results and Discussion
Figure 3 shows the typical cross-sectionof the aramid-based material during thecyclic compressive test. According to Fig.
3(a), the aramid fibers and pre-existingdamage inside of the aramid fiber are
observed. When the compressive stress is
20MPa, a crack propagates from thepre-existingdamage.
Whenthecompressive stress is 50MPa, two aramid
fibers move and are crushed. Therefore,
it seems that the damage occur inside ofaramid fibers.
Figure 4 shows the typical cross-sectionof the cellulose-based material during thecyclic compressive test. According to Fig.
4(a), the cellulose fibers and resin are
observed on the cross-section. It seems
that the fibers are glued each other withthe resin. When compressive stress is
20MPa, the interfacial debonding
between the cellulose fiber and resin
occur. When compressive stress is
50MPa, the interfacial debonding occurs
in other part. Moreover, the crack
initiation is observed inside of thecellulose fiber.
In order to evaluate the damage
behavior of the paper-based friction
material quantitatively, the damage ratio
D is defined as a ratio of the number ofimages containing damages and total
number of images.
D

Number of images containing damages
Total number of images

Figure 5 shows the damage ratio as afunction of compressive stress. For thearamid-based material, when thecompressive stress is 10MPa, the initialdamage occurs and the damage ratio
increases with increasing compressive
stress. When compressive stress is100MPa, the damage ratio is 0.5. For thecellulose-based material, the initialdamage occurs under 5MPa and thedamage ratio increases with increasing
compressive stress, rapidly. Whencompressive stress is 20MPa, the damage
ratio becomes nearly 1.0.
Consequently, the damage in thecellulose-based material occurs underlower compressive stress than in thearamid-based material. Therefore, it
seems that the fatigue life ofcellulose-based material is shorter thanthat of aramid-based material.

Fig.5 Damage as a function stress level.

(1)

Fig.3 Microstructure during cyclic compression test (Aramid-based material).

- 30
Fig.4 Microstructure during cyclic
compression
test (Cellulose-based material).

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Step-wise Intercalation of Polyetheramine and Paraffin in Montmorillonite
Bryan G. Alamani*1, Rizalinda L. De Leon1, Angela D. Escoto1, and Jiang Jen Lin2
1

Department of Chemical Engineering, College of Engineering, University of the Philippines
Diliman, Philippines
2
Institute of Polymer Science and Engineering, College of Engineering National Taiwan
University, Taipei, Taiwan
TEL&FAX: +63-929-6640*
e-mail: bgalamani@upd.edu.ph

1. Introduction
A certain class of organophilic clay
modified by Polyoxypropylene Amine asintercalants has been reported. [1-3] [4, 5]
These polymers render the layered clay,
Montmorillonite in this case, hydrophobic
and then lead to increase in the basal spacingfrom 12Ǻ to 52Ǻ. The mentioned increase
has not been observed in the case of
surfactants [6] and hydrophilic polymers likepolyethylene glycol [7]. The widened gallery
spacing will provide more space for materials
to be incorporated later on with compatibleorganic molecules such organic phase changematerial(PCM). Polyoxypropylene Amines
have mono-, di- & tri-amine functionalities
that can be reacted with an acid to generate acorresponding quaternary ammonium saltthat can interact with the ionic surface of theclay. These molecules, sometimes called
Polyether amines, have the capability of
tailoring the basal spacing expansion ofLayered Silicates such as Montmorillonite(MMT) based on the chain length, molecularweight, number of amine functionalities,
presence of other functional groups in theterminal. [1-4, 8-12]The
current
study
focusesonincorporation of Paraffin (C18H38) as PCM
into the Polyoxypropylene intercalated
Layered Montmorillonite without the use of
Ionic surfactants and just by allowing
common molecular forces brought byintermolecular forces of attraction toincorporate paraffin into the interlayer.
Furthermore, the study places emphasis on
step-wise intercalation in incorporatingorganic phase change material in theorganophilic layered montmorillonite. The
work offers an alternative to the preparation- 31 -of clay without the use of surfactants,
stabilizers and other compatibilizing
materials in order incorporate organic phasechange materials.

2. Step-wise intercalation ofpolyoxypropylene amine andparaffin in montmorillonite
The intercalation of Na+-MMT performedby ionic exchange reaction with HCl acidified
M2000. The procedures for using M2000 asintercalation agent are described below.
Sodium montmorillonite (1.00 g, 1.20
mequiv/g) in 100 g deionized water was
swelled under mechanical stirring at 80 °C
overnight. Acidified M2000 (0.125 g, 35%HCl) was added to the clay slurry at 80 °C for
and allowed to react for one hour. 1 to 10
CEC of C18H38 (0.6096 - 6.096 g) was added
to the polyoxypropylene amine intercalated
clay (MMT/M2000, 1/1 CEC ratio) and thereaction proceeded at temperature of 45 °C
with mechanical stirring. The reaction
proceeded for 5 hrs and product was collected
via vacuum filtration. The final product waswashed 2 to 3 times with water and ethanol toremove excess unreacted salts and organic
phase change material. The product wasdried in the oven at 70 °C for 12 hours.

Fig. 1 Schematic of the preparation of thenanocomposites.

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

3. Results and Discussion
Poly(-oxypropylene) monoamine withapproximate molecular weight of 2000g/mol
or simply M2000 was intercalated in the clay
gallery leading to an enlargement of the basal
spacing up to 71 Å. Addition of excessive
C18H38 led to further expansion of theinterlayer which was analyzed via X-ray
Diffraction.
XRD results revealed anincrease in the d spacing to about 79 to 98 Å.
98 Å was the highest detectable basal spacing
value based on XRD which corresponds to 6
CEC of C18H38 added to the organoclay
MMT/M2000 (CEC ratio, 1/1) whichcorrespond to a single peak. However,further addition of C18H38 was observed togive relatively featureless XRD profile withsome small peak like features. This particularsituation tells the need to use transmission
electron microscopy (TEM) in order to see
the actual basal spacing of the organoclay.

Fig. 2 TEM Images of Phase Change
Nanocomposites.
(A)1/1/6 PHYSICAL MIXTURE (20 nm), (B)
1/1/6 (20 nm), (C) 1/1/10 (20 nm) (D) 1/1/6
PHYSICAL MIXTURE (100 nm), (E) 1/1/6 (100nm), (F) 1/1/10 (100 nm)

1/1/6 PCN revealed a consistent value ofbasal spacing with that of XRD (101 Å).
1/1/10 PCN was found out to have a basal
spacing of 185 Å which may indicate
exfoliation of the clay as this was also
consistent with the featureless profile givenin the XRD data. For reference, the 1/1/6
physical mixture revealed a basal spacing of
15 Å which was not observed in XRD
probably due to large amount of organics thus
making the clay morphology undetectable forthe said instrument.
Thermogravimetric analysis was used indetermining the organic fraction of thecomposite and it has been found out that thephase change nanocomposites have organic- 32 -

content essentially similar to that of thecomposite formulation based on CEC. For
example 1/1/6 based on CEC formulation has
83 % organic fraction and thermogravimetricresults obtained gave a value of 82 %.

4. Conclusion
Nanocomposites were fabricated using
step-wise intercalation of polyoxypropylene
monoamine and paraffin in montmorillonite.
The basal spacing increases as the amount ofintercalants increases. The resulting clay
morphology was observed to be intercalated
and exfoliated depending on the amount oforganic incorporated. Thermogravimetricanalysis has revealed the high organic
fraction for nanocomposites with high basal
spacing.

References[1] C.-C. Chou, F.-S. Shieu, J.-J. Lin,
Macromolecules, 36 (2003) 2187-2189.
[2] C.-C. Chou, Y.-C. Chang, M.-L. Chiang,
J.-J. Lin, Macromolecules, 37 (2003)
473-477.
[3] J.-J. Lin, J.-C. Wei, W.-C. Tsai, The
Journal of Physical Chemistry B, 111(2003) 10275-10280.
[4] J.-J. Lin, Y.-M. Chen, W.-C. Tsai, C.-W.
Chiu, The Journal of Physical ChemistryC, 112 (2003) 9637-9643.
[5] S.-T. Lin, C.-W. Chiu, W.-C. Chen, J.-J.
Lin, The Journal of Physical ChemistryC, 111 (2007) 13016-13021.
[6] Y. Xi, R.L. Frost, H. He, Journal of
Colloid and Interface Science, 305(2007) 150-158.
[7] M.M. Malwitz, A. Dundigalla, V.
Ferreiro, P.D. Butler, M.C. Henk, G.
Schmidt, Physical Chemistry Chemical
Physics, 6 (2004).
[8] J.-J. Lin, J.-C. Wei, T.-Y. Juang, W.-C.
Tsai, Langmuir, 23 (2003) 1995-1999.
[9] J.-J. Lin, Y.-C. Hsu, K.-L. Wei,
Macromolecules, 40 (2003) 1579-1584.
[10] J.-J. Lin, Y.-M. Chen, Langmuir, 20(2004) 4261-4264.
[11] C.-C. Chu, M.-L. Chiang, C.-M. Tsai,
J.-J. Lin, Macromolecules, 38 (2005)
6240-6243.
[12] C.-W. Chiu, C.-C. Chu, S.A. Dai, J.-J.
Lin, The Journal of Physical ChemistryC, 112 (2008) 17940-17944.

Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Influence of particle size and debonding damage on elastic and elastic-plastic
singular fields around a crack-tip in particulate-reinforced composites
Takahiro OMI, Tomoyuki FUJII, Keiichiro TOHGO*3, Daisuke KATO
and Yoshinobu SHIMAMURA
Dept. of Mechanical Engineering, Shizuoka Univ.
Johoku 3-5-1, Naka-ku, Hamamatsu, Shizuoka, 432-8561 Japan

1. Introduction
Particulate-reinforced composites havebeen developed by dispersing particles inmatrix in order to improve mechanical performance of materials. In particulate-reinforced composites, it is reported thatdebonding between matrix and particles orcracking damage of particle affect theirmechanical properties. Tohgo et al. developed a constitutive model taking account ofparticle size effect and damage evolution.
In this paper, a finite element method
based on the constitutive model has beendeveloped. Numerical analyses of a crack-tip
field under three point bending are carriedout for composites containing various sizedparticles. Influence of debonding damage onstress field ahead of a crack-tip is discussed
based on the numerical results.
2. Finite element analysis
2.1 Incremental damage theory Tohgo etal. developed damage theory of composites
taking account of debonding damage evolution based on Eshelby’s equivalent inclusion
method and Mori-Tanaka’s mean field concept(1). The constitutive relation is describedby the form decomposed into the hydrostaticand the deviatric parts as follows:d  kk 1
1 pd kk  kk df
3 t
3 d

1
1 p
d  ij ' d ij '
 ij ' df
2t
2 d

(1)
(2)

where, df is the volume fraction of theparticles to be debonded in the incremental
process, , andare constant values determined by elastic moduli of matrix
and particle.
2.2 Particle size effect The theory described above is extended to consider theparticle size effect by Nan-Clarke’s simple
method. The stress-strain relation is given by
Ramburg-Osgood equation as follows:- 33 -

 0e 

 0e
E0

1/ n



 00   0e 
E0   00 (3),
, and is Young’s modulus,
where,
yield stress and work-hardening exponent,
andis a material constant. Nan-Clarkeassumed that yield stress was affected byparticles, and then modified as follows: 00   00 Bulk   00(4)

where, 00 is the correction term taking
account of the particle size effect and is expressed as a function of particle size d.
In order to consider the particle size effecton damage, it is assumed that the debonding
damage is controlled by a strain energy release rate criterion for particle-matrix interfacial debonding. From energy balance during debonding process of a particle, the critical particle stress for debonding damage isapproximately given as follows: cr 

K IC
d

(5)

where,
is the fracture toughness forinterfacial debonding between the particle
and matrix.
2.3 Particle size distribution A number
distribution of particles is assumed to follow
a lognormal distribution.
p (d )  (ln d   ) 2 
exp  
2 2
2  d1(6)

where,  and  is constant. Influence of eachparticle on macroscopic property of composite described by the volume percentage. The volume percentage of particle
is given bypV ( d ) 1 d p(d )dd3

d 3 p (d )(7)Consequently, some values A, such as thestress and strain, of a composite containing
various sized particles can be obtained by theProceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

3. Analytical results and Discussion

following equation,A   pV ( d ) A( d )dd

(8)

100mm

110mm

where, A(d) exhibits the values for a composite with constant sized particles of d.
2.4 Analytical condition Finite element
method was formulated on the basis of quadrilateral 8-noded iso-parametric elementswith four gauss points. Numerical analysis
was carried out for the composite of
15vol%SiC/A356-T4. The material properties of matrix are E0=70GPa, ν0=0.33,(σ00)Bulk=86MPa, n=0.212, =3/7. The material properties of SiC particles are
Ep=427GPa，νp=0.17 and a particle volume
fraction fp0 is 15%. The mean particle diam̅ 1μm, 7.5μm
eters are set as
and 16μm. Figure 1 shows the three-point
bending specimen and its finite element
mesh. In order to avoid the numerical problem for crack-tip singularity, a sharp notchwith radius of 0.02mm was regard as a crack.
The elastic-plastic fracture mechanics parameter J-integral was calculated by a simple
evaluation method using load-displacement
relations for each stage of deformation.

0.02mmP
yx

25mm A
50mm

Fig. 1 Dimensions of specimen and its finite elemental meshes

2x101
101

3.1 Particle size effect Figure 2 shows thestress distribution at crack-tip taking accountof particle size effect. The stress is normalized by (σ00)Bulk and the distance fromcrack-tip is normalized by J-integral and(σ00)Bulk. From a viewpoint of slope of stress
distribution, HRR singular field expressedby the straight line with the slope of–N/(N+1) (N is work-hardening exponent) isformed in plastic deformation zone near thecrack-tip, and K singular field expressed by astraight line with the slope of -1/2 is formedin elastic deformation zone around the outside of HRR singular field. From a viewpoint of mean particle size, the stress distribution shift upward with decreasing mean
particle size, because the yield stress increases with decreasing particle size.
3.2 Influence of Debonding damage
Figure 3 shows the normalized stress distribution and void volume fraction distribution
at crack-tip in case of mean particle diameterof 16μm. The dotted line denotes the results
considering particle size effect(NDD), andthe solid line denotes the results considering
particle size effect and debonding damage(DD). The stress increases with progressive deformation in the case of no debonding.
The debonding initiates from a crack-tip andthe stress at the debonding area is lower thanthat of no debonding in the case of consideration of debonding. The stress reduction
around crack-tip is attributed to loss of load
carrying capability of particle by debonding
between particles and matrix. The area of
debonding damage is corresponding to thatof stress reduction, and the debonding damage affects the stress reduction around a
crack-tip with progressive deformation.

N+1Ny/(00)Bulk

2

100

10

-1

10-2
10-2

Plastic zone
(J=1.0103J/m2)

1

7.7103J/m2
3.5103J/m2

d=1m
d=7.5md=16m10-1

1.0103J/m2
3.6102J/m2
J=1.1102J/m2

100 101 102
x/(J/(00)Bulk)

103

104

Fig. 2 Distributions of the stress ahead of a crack-tipwithout

Fig. 3 Influence of debonding damage on distributions of thestress ahead of a crack-tip in the composite of d =16m.

debonding damage.

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Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

Synthesis and Characterization of Microencapsulated N-Octadecanein Urea-Melamine-Formaldehyde Shell for Thermal Regulation
Dr. Angela Escoto*, Karl Ezra S. Pilario**, John Gerald S. Reamillo and Noel S. Sabarillo
Department of Chemical Engineering, College of Engineering, University of the Philippines-Diliman,
1101 Diliman Campus, Quezon City, NCR, Philippines
Tel. No.: 929-6640*Adviser, E-mail: angie_escoto@yahoo.com**E-mail: kspilario@gmail.com

1. Introduction

mixture of SDS surfactant, resorcinol, and noctadecane homogenized for 1.6 hours. The twowere then mixed and homogenized at 4400 rpm,
includingpH
regulation
tocontrol
polymerization. Microencapsulation is done
after 2 hours, and samples were taken fromdifferent layers in the mixture. They must, then,be filtered from unencapsulated core and excess
shell materials. After vacuum filtration, thesamples must be dried for 8-10 hours in a
gravity oven. Figure 1 shows the final productprior to characterization.

Phase change materials (PCMs) have theability to maintain a steady temperature uponchanging phase. These materials are currently
used for heat storage and space cooling. This
research primarily aims to conduct preliminary
observations in the surface cooling ofpolyurethane foams using PCM technology.
Polyurethane foam is the material of
construction of car seats and pillows, whose
temperatures can reach 60˚C-70°C when cars areparkedunder
thesun. A modified
microencapsulation technique will be used tosynthesize a PCM with n-octadecane and ureamelamine-formaldehyde as core and shellmaterials respectively. The modified technique istailored to the availability of reagents and thetime and equipment constraints in thePhilippines.
The four main objectives of the study are:(1) To develop a modified methodology adaptedfrom Zhang et al for microencapsulation; (2) To
synthesize a microencapsulated PCM with noctadecane as the core material and ureamelamine-formaldehyde (UMF) as the shellmaterial; (3) To characterize the PCM as to its
phase change temperature and latent heat offusion, and; (4) To determine the magnitude of
reduction in the temperature profiles of PCMcovered polyurethane foams exposed in a heatedenvironment.

Fig. 1 Microencapsulated PCM prior toCharacterization

3. Differential Scanning Calorimetry &Temperature Profiling
Characterization is of two parts: Differential
Scanning Calorimetry with calibration andtemperature profiling using a Data Logger. The
generated thermograms were plots of heat flux
against the temperature of a sample. Inside theDSC, the sample was heated and cooled for two
cycles—determining cycling stability. Phasechange temperatures and latent heats wereidentified through TA Instruments Operating
Software integrated into the DSC.

2. PCM Synthesis: Microencapsulation
by In Situ Polymerization
For synthesis, two mixtures were prepared:
the pre-polymer solution and the emulsion. The
pre-polymer solution contained urea, melamine,and formaldehyde at established proportions,
together with distilled water. The emulsion is a

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Proceedings of Philippines-Japan Joint Workshop on Materials for Safe and Sustainable Society 2012

After choosing the best sample, temperature
profiling was started by creating a 1 x 1 x 2 ft
wooden box with a bulb on its hinged lid as heatsource. The best sample was used to completely
cover the top surface of foam manually.
Together with the control/blank foam and a pure
PCM sample, the covered foam was subjected toheating and cooling. Temperature probes were
provided for each, as well as the ambient
temperature. Hydra Data Logger tabulated andprofiled the temperatures for a period of 1.5
hours.

temperature profiles of the materials during
heating are presented on Figure 3.

4. Results and Discussion

Fig. 3 Temperature profile of the PCM,
foam, and ambient temperature during heating

Figure 2 shows the thermogram of the best
sample where the heating cycle is analyzed. The
generated peak melting temperature is 1.6˚Clower, and the latent heat of fusion is 23.8 J/ghigher compared to the results obtained in theoriginal study by Zhang et al. This implies thatthemodified
methodology
yieldedmicroencapsulated products with better thermal
properties, since a lower peak temperature andhigher latent heat of fusion would result to amore appealing environment for human comfort.

5. Conclusion
Based from ocular observations and theresults of the DSC characterization, noctadecane was successfully microencapsulated
in urea-melamine-formaldehyde shell. The best
microcapsule samples had a peak melting
temperature of 34.9˚C and a latent heat of fusionof 190.8 J/g. From the preliminary observations
done in temperature profiling, the product isthermally feasible for polyurethane foam
applications, like in car pillows and car seats.

6. References[1] Alkan, C., Sari, A., and Karaipekli, A. 2010.
Preparation, thermal properties and thermal
reliabilityofmicroencapsulated
noctadecane as novel phase change material
for thermal energy storage. Energy
Conversion and Management 52 (2011)
687–692[2] Mehling, H. and L. F. Cabeza. 2008. Heatand Cold Storage with PCM: An up to dateintroduction into basics and applications.
Springer-Verlag
BerlinHeidelberg.
Germany.

Fig. 2 Thermogram of the sample with thehighest latent heat and favorable melting point
From
thepreliminary
observations
conducted to compare the temperature responsesof the microencapsulated product andpolyurethane foam when exposed under thesame heating conditions, it was observed that thetemperature of the product was lower by anaverage of 3.56˚C relative to the blankpolyurethane foam sample, and by an average of
1˚C relative to the ambient temperature. The[3] Zhang, X., Fan, Y., Tao, X., & Yick, K.
(2004). Fabrication and properties of
microcapsules and nanocapsules containing
n-octadecane. Materials Chemistry andPhysics , 300–307.

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