bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microporous membranes of isotactic poly(4‐methyl‐1‐pentene) from a melt‐extrusion process. II. Effects of thermal annealing and stretching on porosity
Authors: Johnson Matthew B. , Wilkes Garth L. 
Published: August 2002

AbstractA two‐part study utilizing isotactic poly(4‐methyl‐1‐pentene) (PMP) was undertaken to investigate a three‐stage process (melt‐extrusion/annealing/uniaxial stretching) (MEAUS) utilized to produce microporous films. In this report, the thermal‐annealing (second stage) and subsequent uniaxial‐stretching (third stage) results of selected PMP films from three resins, labeled A, B, and C, are discussed. From sequential analysis of the effect each stage had on the resulting microporosity, it was discovered that the melt‐extruded precursor morphology and orientation, as a consequence of the first‐stage extrusion parameters and resin characteristics, were crucial to controlling the membrane permeability. The annealing parameters were also critical, where a temperature of 205°C applied for 20 min under no tension was the optimum annealing condition for producing highly microporous PMP films upon stretching. For the conditions studied, the stretching parameters that were found to be the optimum for producing the desired characteristics in the final film were cold‐ and hot‐stretch temperatures of 70 and 180°C, respectively. The cold‐ and hot‐stretch extension levels concluded to be the best were a cold‐stretch extension of 80%, followed by hot stretching to 90%, and, thus, a total overall extension level of 170% for the processing window studied. However, these results were only with respect to resin A films, while resin B and C samples could not be produced into microporous films via the MEAUS process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1076–1100, 2002; DOI 10.1002/app.10395
Crosslink reaction of natural rubber with thiuram sulphur donors in the presence of a thiuram monosulfide
Authors: González L. , Rodríguez A. , Del Campo A. , Marcos‐Fernández A. 
Published: August 2002

AbstractThe vulcanization of natural rubber was studied with the sulfurating agents dipentamethylene thiuram tetrasulfide (DPTT) and tetramethylene thiuram disulfide (TMTD) in the presence of tetramethyl thiuram monosulfide (TMTM). This last accelerant affects the rate and efficiency of the vulcanization as well as the structures of crosslinks formed by the two sulphur donors. It may give rise to a polymerization between adjacent double bonds and generate a inhomogeneous crosslink distribution with an adverse effect on physical properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 491–499, 2002
Fracture behavior of rubber‐modified injection molded poly(butylene terephthalate) with and without short glass fiber reinforcement
Authors: Yow B. N. , Ishiaku U. S. , Ishak Z. A. Mohd , Karger‐Kocsis J. 
Published: August 2002

AbstractFracture behavior of poly(butylene terephthalate) (PBT) and its rubber‐toughened (RT) 10 wt %) grades; ethylene‐co‐glycidyl methacrylate‐co‐methacrylate terpolymer‐toughened poly(butylene terephthalate) PBT/AX8900 (90/10), and Paraloid acrylic‐based rubber‐toughened poly(butylene terephthalate) PBT/EX2314 (90/10) was investigated using the fracture mechanics approach. The effects of controlling parameters such as type of impact modifier and deformation rate on fracture behavior of PBT and RT‐PBT were investigated. Fracture tests were carried out on notched compact tension (CT) specimens. Fracture toughness, Kc, and fracture energy, Gc, of PBT decreased as the test speed increased from 1 to 500 mm/min. An opposite trend was observed in PBT/AX8900 and PBT/EXL2314. The fracture properties of 30 wt % short glass fiber‐reinforced PBT (SGF‐PBT) and 10 wt % impact‐modified PBT composite (SGF‐RT‐PBT) were also studied. Incorporation of SGF into PBT has profoundly increased the fracture properties both at high and low speed. However, inclusion of 10 wt % of AX8900 into the reinforced PBT (PBT/AX8900/SGF) (60/10/30) adversely affected the fracture properties. EXL2314, on the other hand, showed a different effect, especially at high testing speed. Both types of impact modifiers were able to retain the flexural strength and flexural modulus of PBT. However, PBT/EXL2314 showed a better retention of flexural properties than PBT/AX8900. Incorporation of SGF in the EXL2314‐toughened PBT, i.e., PBT/EXL2314/SGF (60/10/30) also gave a better balance of flexural properties compared to PBT/AX8900/SGF (60/10/30). Both PBT/AX8900 and PBT/EXL2314 showed enhancement of impact strength on the unnotched specimens. The failure modes of CT and impact specimens of PBT, RT‐PBTs, and SGF‐RT‐PBTs were assessed using a scanning electron microscope (SEM). Brittle failure was observed for CT specimens of PBT at high testing speed, while incorporation of the impact modifier AX8900 and EXL2314 resulted in a shift of failure mode from brittle to ductile. SEM micrographs also revealed extensive fiber pull out in SGF‐PBT and SGF‐RT‐PBT. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1233–1244, 2002; DOI 10.1002/app.10446
Blends containing amphiphilic polymers IV. Poly(N‐1‐alkyl itaconamic acids) with poly(2‐vinylpyridine) and poly(4‐vinylphenol)
Authors: Urzua Marcela , Gargallo Ligia , Radić Deodato 
Published: August 2002

AbstractThe phase behavior of blends containing Poly(N‐1‐alkyl itaconamic acids) (PNAIA) with Poly(2‐vinylpyrindine) (P2VPy) and Poly(4‐vinylphenol) (P4VPh) were analyzed by Diferential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR). Miscibility over the whole range of compositions is observed in both systems. All the blends show thermograms exhibiting distinct single glass transition temperatures (Tg), which are intermediate to those of the pure components. The Calorimetric Analysis using Gordon Taylor, Couchman, and Kwei treatments allows conclusion that interactions between the components is favorable to the miscibility. FTIR analysis of the blends suggests that the driving force for miscibility is hydrogen bonding formation. The variation of the absorptions of the carbonyl groups of PNAIA and the hydroxyl groups of P4VPh allows one to attribute the miscibility to weak acid base like interactions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1245–1250, 2002; DOI 10.1002/app.10453
In vitro degradation of poly(L‐ lactic acid) fibers in phosphate buffered saline
Authors: Yuan Xiaoyan , Mak Arthur F. T. , Yao Kangde 
Published: August 2002

AbstractIn vitro degradation of poly(L‐lactic acid) (PLLA) fibers was studied by incubating the fibers in phosphate buffered saline (pH 7.4) at 37°C for 35–45 weeks. Three kinds of PLLA fibers with different diameters and different initial viscosity‐average molecular weights were tested. The viscosity‐average molecular weight, crystallinity, morphology, and tensile properties of the PLLA fibers were monitored along the degradation period. The results showed that the viscosity‐average molecular weight of the PLLA fibers dropped gradually during the in vitro degradation period, and it decreased by 40–60% at the end of the experimental period. The crystallinity of the PLLA fibers measured by differential scanning calorimetry was noted to increase slightly. The tensile moduli, ultimate strengths, and elongations of the fibers did not exhibit significant changes in 35 weeks of degradation but PLLA fibers with a smaller diameter of 113 μm showed significant decreases in their ultimate strengths with respect to the initial value after 35–45 weeks of degradation. Microcracks appeared on part of the fiber surfaces, which might ultimately lead to the decrease of the mechanical strength of the PLLA fibers. The spotty defects reported in this study apparently did not affect the mechanical properties of the fibers. The results suggested that the tensile properties of the PLLA fibers were mechanically stable in 35 weeks of in vitro degradation, although their molecular weights decreased remarkably and obvious spotty defects appeared on their surfaces. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 936–943, 2002
Molecular design of damping rubber based on polyacrylate‐containing silicone
Authors: Huang Guang‐Su , Jiang Lu‐Xia , Li Qiang 
Published: August 2002

AbstractA series of damping rubbers based on poly(meth)acrylate and poly(meth)acrylate‐containing silicone rubbers has been prepared. The dynamical mechanical properties were evaluated by using a dynamic mechanical viscoelastometer (DMA). A detailed investigation is reported on the relationship of the damping capability of the poly(meth)acrylate rubbers with their composition and macromolecular architecture. Also discussed is the effect of two kinds of silicone elastomers on the damping performance of the polyacrylate‐containing silicone rubber. The results indicate that, in vulcanized rubber systems, both statistical copolymerization for multiple monomers and blending between immiscible polymers with close Tgs facilitate broadening the glass transition peaks. Furthermore, the molecular design is quite an effective approach in which the multiple monomers whose polymers have a ladder‐changing Tg are used to synthesize the damping rubber with the broad effective functional area. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 746–751, 2002
Preparation of polymer/inorganic nanoparticles composites through ultrasonic irradiation
Authors: Wang Qi , Xia Hesheng , Zhang Chuhong 
Published: August 2002

AbstractIn this paper, ultrasonic induced encapsulating emulsion polymerization was first used to prepare the novel polymer/inorganic nanoparticles composites. The behaviors of several inorganic nanoparticles (SiO2, Al2O3, TiO2) under ultrasonic irradiation, such as dispersion, crushing, and activation, were studied. The dispersion stability, morphology, and structure of the ultrasonic irradiated nanoparticles were characterized by means of transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and spectrophotometry, respectively. The results show that the inorganic nanoparticles in the aqueous solution can redisperse more effectively by ultrasonic irradiation than by conventional stirring. This is the basis for preparation of polymer/inorganic nanoparticles composites. By this technique, the long‐term stable latex, which mainly consists of polymer/inorganic nanoparticles composite latex particles, were successfully prepared. TEM, FTIR, thermogravimetric analysis, X‐ray photoelectron spectroscopy, spectrophotometry, and element analysis confirmed that well‐dispersed nanoparticles were encapsulated by the formed polymer, and the thickness of encapsulating polymer layer was in the range of 5–65 nm. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1478–1488, 2001
Rigid, thermosetting liquid molding resins from renewable resources. I. Synthesis and polymerization of soy oil monoglyceride maleates
Authors: Can E. , Küsefoğlu S. , Wool R. P. 
Published: August 2002

AbstractIn this study, rigid thermoset polymers were prepared from radical copolymerization of the soybean oil monoglyceride maleates with styrene. In the first part of the study, soybean oil monoglycerides (SOMGs) were obtained from the reaction of soybean oil with glycerol at 220–240°C with an optimization of the reaction to maximize the monoglyceride yield. In the following step, SOMG were reacted with maleic anhydride at temperatures around 100°C to produce the SOMG maleate half esters. Different catalysts and different reaction conditions were examined to increase the maleate half esters' yields. The reactions were followed by IR and 1H NMR, and the products were characterized by mass spectrometry. In the final step, the radical initiated copolymerization of the SOMG maleates with styrene produced rigid, thermoset polymers. The emulsion copolymerization of the SOMG maleates with styrene was also carried out successfully without the addition of an emulsifier. The obtained polymers were characterized by IR and the crosslinked network structure of the copolymers was examined with the swelling behavior in different solvents. Mechanical properties of the cured resin such as Tg, dynamic flexural modulus, and surface hardness were also determined. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 69–77, 2001
Hygrothermal aging and tensile behavior of injection‐molded rice husk‐filled polypropylene composites
Authors: Ishak Z. A. Mohd. , Yow B. N. , Ng B. L. , Khalil H. P. S. A. , Rozman H. D. 
Published: August 2002

AbstractThe effect of the filler volume fraction on the tensile behavior of injection‐molded rice husk‐filled polypropylene (RH–PP) composites was studied. Hygrothermal aging behavior was also investigated by immersing the specimens in distilled water at 30 and 90°C. The kinetics of moisture absorption was studied from the amount of water uptake by specimens at regular interval times. It was found that the diffusion coefficient and the maximum moisture content are dependent on the filler volume fraction and the immersion temperatures. Incorporation of RH into the PP matrix has led to a significant improvement in the tensile modulus and a moderate improvement in the tensile strength. Elongation at break and energy at break, on the other hand, decreased drastically with the incorporation of the RH filler. The extent of deterioration incurred by hygrothermal aging was dependent on the immersion temperature. Both the tensile strength and tensile modulus deteriorated as a result of the combined effect of thermal aging and moisture attack. Furthermore, the tensile properties were not recovered upon redrying of the specimens. Scanning electron microscopy was used to investigate the mode of failure of the RH–PP composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 742–753, 2001
Thermooxidative decomposition and its kinetics on chlorinated natural rubber from latex
Authors: Zhong Jie‐Ping , Li Si‐Dong , Yu He‐Ping , Wei Yong‐Cai , Peng Zheng , Qu Ju‐Lan , Guo Chen‐Kun 
Published: August 2002

AbstractThermooxidative decomposition and its kinetics on chlorinated natural rubber (CNR) from latex are studied by thermal gravimetry (TG) analysis and TG coupled with FTIR spectroscopy. The thermooxidative decomposition of CNR is a two‐step reaction. The first step is the reaction of dehydrochlorination of which the reaction order (n) is 1.1; the reaction activation energy (E) increases linearly with the increment of the heating rate (B), and the apparent activation energy (E0) is 101.7 kJ/mol. The initial temperature of weight loss (T0) is 1.29B + 248.7, the final temperature of weight loss (Tf) is 0.86B + 312.4, and the temperature at the maximum weight loss ratio (Tp) is 1.05B + 286.2. The decomposition ratio at Tp (Cp) is not affected by B, and its average value is 38%. The decomposition ratio at Tf (Cf) is also not affected by B, and its average value is 60%. The second step is an oxidative decomposition reaction of the molecular main chain. The value of n is 1.1, E increases linearly with the increment of B, E0 is 125.0 kJ/mol, the relation between B and T is similar to that of the first step, and Cf approaches 100%. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1305–1309, 2001
Rheological and curing behavior of reactive blending. I. Maleated natural rubber–cassava starch
Authors: Nakason C. , Kaesman A. , Homsin S. , Kiatkamjornwong S. 
Published: August 2002

AbstractMaleated natural rubber (MNR) was prepared and used as a blending composition and a compatibilizer for blending of natural rubber (STR 5L) and cassava starch. The melt rheological behavior in terms of Mooney viscosity, apparent shear stress, and shear viscosity at 100°C were quantified. We found that the pure MNR gave the lower apparent shear stress, shear viscosity than did those of the blends with cassava starch. The rheological data of the MNR blends increased with increasing quantity of cassava starch. The highest value was observed for the blend of MNR. The rheological value was as follows: MNR > STR 5L with MNR (as the compatibilizer) > STR 5L compounds. Furthermore, rheological properties increased with increasing the levels of compatibilizer (MNR). The rheological results were described in terms of intermolecular interaction between the polar groups in the natural rubber and cassava starch molecules. Each rubber blend was compounded, and their curing characteristics were studied. The pure MNR compounds exhibited a long delayed onset of vulcanization for approximately 10 min. The retardation was found, because the accelerator (MBT) reacted with the anhydrides in the compound instead of acting as an accelerator. The retardation was not observed for the compound with the cassava starch. The curing curves for all MNRs were not in equilibrium at a maximum torque, while the pure STR 5L compound gave a curing curve with a maximum torque and a slight reversion. The curing curve for the compound with MNR as the compatibilizer was a combination of the curing curves of MNR and STR 5L. That is, the curve was in equilibrium at the maximum torque and the short delayed action. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2803–2813, 2001
Effects of moisture content and heat treatment on the physical properties of starch and poly(lactic acid) blends
Authors: Ke Tianyi , Sun Xiuzhi 
Published: August 2002

AbstractStarch, a hydrophilic renewable polymer, has been used as a filler for environmentally friendly plastics for about 2 decades. Starch granules become swollen and gelatinized when water is added or when they are heated, and water is often used as a plasticizer to obtain desirable product properties. The objective of this research was to characterize blends from starch and poly(lactic acid) (PLA) in the presence of various water contents. The effects of processing procedures on the properties of the blends were also studied. Blends were prepared with a lab‐scale twin‐screw extruder, and tensile bars for mechanical testing were prepared with both compression and injection molding. Thermal and mechanical properties of the blends were analyzed, and the morphology and water absorption of the blends were evaluated. The initial moisture content (MC) of the starch had no significant effects on its mechanical properties but had a significant effect on the water absorption of the blends. The thermal and crystallization properties of PLA in the blend were not affected by MC. The blends prepared by compression molding had higher crystallinities than those prepared by injection molding. However, the blends prepared by injection molding had higher tensile strengths and elongations and lower water absorption values than those made by compression molding. The crystallinities of the blends increased greatly with annealing treatment at the PLA second crystallization temperature (155°C). The decomposition of PLA indicated that PLA was slightly degraded in the presence of water under the processing temperatures used. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3069–3082, 2001
Condensation–addition‐type resole resins with phenyl ethynyl functions: Synthesis, characterization, and thermal properties
Authors: Reghunadhan Nair C. P. , Bindu R. L. , Ninan K. N. 
Published: August 2002

AbstractNovel phenolic resins bearing methylol and phenyl ethynyl functions and curing by both condensation and addition mechanisms were synthesized by the reaction of 3‐(phenyl ethynyl) phenol (PEP) with formaldehyde under alkaline conditions. Resins with varying relative concentration of the two functional groups were synthesized and characterized. The resins underwent a two‐stage cure, confirmed by both DSC and DMA analyses. The low‐temperature cure due to methylol condensation led to early gelation of the system. The ultimate curing through addition reaction of phenylethynyl group required heating at 275°C. The cured resins exhibited better thermal stability and anaerobic char yield in comparison to a conventional resole. The thermal stability and char‐yielding property showed a diminishing trend with enhanced methylol substitution. Resin with F/P ratio less than unity offered excellent thermal stability and anaerobic char yield. The thermal degradation of the cured resins occurred in two kinetic steps. Methylene groups favored the initial degradation, whereas the higher temperature carbonization process was independent of the network structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3371–3377, 2001
Effect of alkalinity on the structure of phenol–formaldehyde resol resins
Authors: Luukko Petra , Alvila Leila , Holopainen Timo , Rainio Jouni , Pakkanen Tuula T. 
Published: August 2002

AbstractTwo phenol–formaldehyde resol resin series with different methylation‐ and condensation‐stage alkalinities were studied. The first series was impregnation resins having a methylation alkalinity between 0.5 and 1.5 wt % and a condensation alkalinity of 1.5 wt %. The second series was adhesive resins with a methylation alkalinity between 0.5 and 3.5 wt % and a condensation alkalinity of 6.0 wt %. The chemical structure was analyzed by 13C‐NMR spectroscopy, and reactivity, by differential scanning calorimetry (DSC). The methylation alkalinity was found to affect the distribution of the structural groups of both phenol–formaldehyde impregnation and adhesive resins, but not to the same extent as did the total condensation alkalinity. Also, the results of the DSC analysis illustrate best the reactivity differences due to the condensation alkalinity. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 258–262, 2001
Effect of atmosphere on the thermal decomposition of chlorinated natural rubber from latex
Authors: Li Si‐Dong , Cheung Man Ken , Zhong Jie‐Ping , Yu He‐Ping 
Published: August 2002

AbstractThe kinetics of the thermal decompositions of chlorinated natural rubber (CNR) from latex under both air and nitrogen atmospheres were studied with thermogravimetric analysis (TGA). The thermooxidative decomposition of CNR had two weight‐loss step changes in the TGA curves, which occurred at the two distinct temperature ranges of about 160–390 and 390–850°C, respectively. The gaseous products of the first step change were mainly HCl with a little CO2, and the apparent reaction order (n) was 1.1. The reaction activation energy (E) increased linearly with the increment of heating rate (B), and the apparent activation energy (E0), calculated by extrapolation back to zero B, was 101.7 kJ/mol. Bs ranging from 5 to 30°C/min were used. The initial temperature of weight loss (T0) was 1.31B + 252°C, where B is in degrees Celsius per minute. The final temperature of weight loss (Tf) was 0.93B + 310°C, and the temperature of maximum weight‐loss rate (Tp) was 1.03B + 287°C. The decomposition weight‐loss percentage at Tp (Cp) and that at Tf (Cf) were not affected by B, and the average values were 38 and 60%, respectively. The second weight‐loss step change was an oxidative decomposition of the molecular main chain. The value of n was 1.1. E increased linearly with the increment of B, and E0 was 125.0 kJ/mol. Cf after the second step approached 100%, which indicated complete decomposition. The thermal decomposition of CNR in a N2 atmosphere had only one weight‐loss step change with an n of 1.1. E increased linearly with the increment of B, and E0 was 98.6 kJ/mol. T0 was 1.25B + 251°C, Tf was 0.91B + 315°C, and Tp was 1.09B + 286°C. Cp and Cf were not affected by B, and the average values were 37 and 68%, respectively. The weight percentage of more stable, nonthermal decomposed residue was about 30%. The thermal decompositions of CNR in both atmospheres were similar, mainly by dehydrochlorination, at the low temperature range (160–390°C) but were different at the high temperature range (390–850°C). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2590–2598, 2001