bluuebunny/crossref_metadata_2025 huggingface dataset:
Internal Structure of Short Glass Fiber Reinforced Polyamide 66 Injection Moldings by Acoustic Velocity Measurement
Authors: Kuriyama Takashi , Mizoguchi Machiko , Odaka Satoshi , Sorimachi Hidemitsu
Published: September 2018

Internal structure of short glass fiber reinforced polyamide 66 injection moldings were investigated by optical microscopes, scanning electron microscopy, and acoustic velocity measurement. The apparent four phases could be found and they were classified by their crystallinity and fiber orientations from the observations of micrographs. Such structure could be seen in acoustic velocity map. The difference in acoustic velocity could express the difference in phases. Acoustic velocity measurement was carried out before and after static tensile test, and fracture due to stress concentration of core region could be well understood.
Investigation of Melt-Intercalated PET-Clay Nanocomposites
Authors: Yuan Maoquan , Pan Xiangjiang , Wan Chaoying
Published: September 2018

Poly(ethylene terephthalate)/montmorillonite (PET/MMT) nanocomposites were prepared by a melt-intercalating method. The MMT was organically modified by hexadecyl trimethyl ammonium bromide and poly (ethylene glycol) prior to use. The microstructure of the nanocomposites was investigated by wide angle X-ray diffraction and transmission electron microscopy. The results showed that the organic MMT layers were exfoliated and dispersed in nanoscale in the PET matrix.
Biodegradation Studies of Starch Based Composite Superabsorbents
Authors: Sahoo Prafulla K. , Rana Pradeep K. , Sahoo Anusmita
Published: September 2018

The potential of a new starch based composite consisting of acrylamide, a crosslinking agent, N,N'methylene-bis-acrylamide and sand (white quartz) to act as a superabsorbent polymer was investigated. The modification of starch by grafting with acrylamide induced hydrophilic behaviour in the matrix, which increased its water absorbing capacity remarkably and also enhanced its biodegradability by sludge water and microorganisms (Bacillus cereus and Eischerichia coli). The amount of carbon dioxide released during biodegradation was studied and the process of biodegradation through soil burial was also investigated. The composite was characterized by IR, TGA and XRD techniques. The XRD data reveals the composites to be more crystalline than starch and homopolymer. The surface morphology was examined by SEM, and was found to show distinct differences after biodegradation. The composite may be used as a water retainer for agricultural and horticultural purposes in desert and drought-prone areas.
An Interesting Phenomenon in Dispersion Polymerisation of Styrene: The Relationship between Conversion and Quantity of Microspheres
Authors: Wang Diqiang , Li He , Liu Bailing , Chu Jianyun
Published: September 2018

A phenomenon which has been ignored in most previous research, i.e., the relationship between conversion and the actual amount of microspheres in the dispersion polymerisation of styrene, has been researched. This led to a discussion of the polymerisation mechanism and the microsphere preparation process. The results showed that the actual amount of microspheres was always lower than the conversion, and the ratio of the two was different in different media. They also showed that with the decreasing polarity and solubility parameter of the medium, the conversion of styrene gradually reduced, and the character of the polymerisation was partly emulsion and partly solution. The average diameter and distribution of the microspheres in ethanol-water, ethanol, isopropanol and butanol were investigated too, and it was found that they increased with increasing polarity of the medium.
Investigation into Polyhydroxybutyrate Morphology under the Influence of Varying Solvent Type
Authors: Sharma Lakshmi , Nishida Koji , Kanaya Toshiji
Published: September 2018

Polyhydroxybutyrate is a natural polymer that undergoes secondary crystallisation rendering the material brittle. This brittleness problem can be reduced by using a plasticiser. In this study, the influence of the solvent, (chloroform, acetone and toluene) as a plasticiser, on polyhydroxybutyrate was investigated. The polyhydroxybutyrate crystalline and amorphous FT-IR bands in the 950-1850 cm-1 region were studied. No band change was identified between the different solvent systems rendering the conclusion that the solvent is not an influencing factor to PHB's crystalline and amorphous regions. Hot stage optical microscopy was also employed to further substantiate the FT-IR studies. However, a distinct and marked change between the solvents and pure PHB became evident. The growth rate decreased for all solvents compared to the homopolymer indicating a non-plasticising effect.
Structure and Crystallization Behaviour of Poly(∊-caprolactone)/Clay Intercalated Nanocomposites
Authors: Kiersnowski Adam , Kozak Maciej , Jurga Stefan , Pigłowski Jacek
Published: September 2018

Nanocomposites of poly(∊-caprolactone)/M-HTAB were obtained by polymerization of caprolactone with various amounts (10, 30, 50 and 64 weight ratio) of montmorillonite organophilized with hexadecyltrimethylammonium bromide (HTAB).

The microstructure of nanocomposites was studied by small angle X-ray scattering (SAXS). Additionally, the melting enthalpies (ΔHm), the crystallinities and the half-time of isothermal crystallization were evaluated by differential scanning calorimetry (DSC).

As a result of SAXS experiments for the composite PCL/M-HTAB 90/10, in the temperature range from 313 to 283 K, a rapid change in the interlamellar distance from 3.1 nm to 2.72 nm was observed. Similar scattering curves were obtained for the nanocomposite PCL/M-HTAB 70/30. In the composites containing 50% and 64% wt of M-HTAB, the decrease in interlayer distance was less pronounced in the same temperature range (d001 3.15 – 3.2 nm).

DSC results clearly showed that the crystallization is divided into two separate processes: primary crystallization in the PCL matrix, and secondary crystallization.
Effects of Surface Treatment of Co3O4 Particles on the Properties of Polymethylphenylsiloxane Based Nanocomposites
Authors: Sun J.T. , Huang Y.D. , Cao H.L. , Gong G.F.
Published: September 2018

Polymethylphenylsiloxane (PMPS) was filled with Co3O4 nano-particles to prepare nanocomposites with thermal absorption properties (also called as endothermal properties). The surfaces of the nano-particles were treated by covalently bonding them to polybutylmethacrylate (PBMA) by an emulsion grafting method, and their surface characteristics after treatment are reported. The effects of treating the Co3O4 nano-particles on the interfacial properties, thermal properties (thermal stability of materials) and endothermal properties of the nanocomposites were investigated by means of a dynamic wetting instrument, transmission electron microscopy (TEM), differential thermogravimetry (DTG) and by a calibration test of the heat flow transducer. The results indicate that PBMA had been grafted onto the surfaces of the Co3O4 nano-particles successfully, and the grafting ratio reached about 6.6%. After the grafting treatment the hydrophilicity of the Co3O4 particles decreased and the hydrophobicity increased. The miscibility between Co3O4 particles and PMPS was increased, and their dispersion in PMPS was also improved. Compared with pure PMPS resin, the thermal stability of the untreated Co3O4/PMPS composites decreased, but increased to some extent for treated Co3O4/PMPS composites. The calibration test of the heat flow transducer revealed that the nanocomposite with grafted Co3O4 nano-particles had much better endothermal properties than the one with untreated Co3O4 nano-particles.
Manufacturing and Characteristics of Copper Clad Laminates based on Glass Cloth and Polytetrafluoroethylene
Authors: Futian Hu , Jiang Cheng , Xiufang Wen , Pihui Pi , Zhuoru Yang
Published: September 2018

This study concerned the manufacture of copper clad laminates using glass cloth/pol ytetrafluoroethylene(PTFE), and the effects of silane treatment on the flexural strength and morphology of the resulting prepregs. About 40 wt% glass cloth in PTFE gave the highest flexural strength. The adhesion to copper was greatest when the glass cloth content was 20 wt% in the prepregs. Finally, the prediction of the dielectric properties was discussed.
Measurement of the Average Permeability of Natural Fibre Mai in Resin Transfer Moulding Application
Authors: Rouison David , Couturier M. , Panthapulakkal S. , Sain M.
Published: September 2018

The permeability of hemp fibre mats used in a resin transfer moulding process were computed from the measured mould filling time, using a simplified mathematical approach. This approach could be applied because of the simple geometry of the mould and because a certain number of assumptions were made The permeability values obtained were found to decrease with increasing fibre content. In addition the hemp fibre permeability was found to be an order of magnitude lower than the value for glass fibre at a fibre content of 19 vol%. This preliminary work shows the importance of studying the permeability of natural fibre systems in order to provide the data necessary for the proper design of industrial moulds.
Contact Angle of Epoxy Resin Measured by Capillary Impregnation and the Wilhelmy Technique
Authors: Li Min , Zhang Zuo Guang , Sun Zhi Jie
Published: September 2018

Good wetting plays an important role in improving the degree of adhesion at interfaces between fibres and matrices in composites. The contact angle of an epoxy resin, as a widely used polymeric matrix, was studied by impregnation in single glass capillaries at the manufacturing temperature of the composites. In order to obtain the net wicking mass for capillary experiments, the meniscus force at the bottom of the glass tube was investigated, with the help of the Wilhelmy technique, conducted by using glass sticks with various diameters. Results show that the contact angles resulting from equilibrium using both capillary impregnation and the Wilhelmy experiment are consistent, which indicates the reliability of the practical evaluation of the effect of the meniscus on the penetration mass. The contact angle of this epoxy resin was approximately 60° resulting from the equilibrium of the capillary impregnation and the Wilhelmy experiments at 80°C.
Semi-Interpenetrating Conducting Elastomer Composite Thin Films from Polyaniline
Authors: Sreeja R. , Sharma P.D. , Najidha S. , Jayan S. Remya , Predeep P.
Published: September 2018

The blending of conducting polyaniline (PANI) with elastomers (natural rubber (NR) and acrylonitrile-butadiene rubber (NBR)) by a wet mixing process has been studied with the goal of fabricating flexible ultra thin conducting films. Good conductive properties were found for NR composite films with 30 wt% of HCl treated PANI and NBR composite films with 20 wt% of HCl treated PANI. There was a gradual decrease in surface resistivity with increasing PANI (HCl) concentration. The UV/VIS spectra indicated the presence of conjugated sequences of conducting polyaniline in the composite films. The FT-IR/

ATR results indicated the compatibility of HCl doped PANI with both NR and NBR and hence better mechanical properties, as indicated by an increase in the Young's modulus. Thus the conducting component acted simultaneously as reinforcement and conductive filler for both matrices. However the NBR composites became harder and more brittle with the increase in PANI concentration. The results have been correlated with swelling measurements confirming the formation of an interpenetrated network, which inhibits rubber solubilization. The method opens up a new technique for preparing stable conductive thin films of PANI using dopants such as HCl.
The Characteristics of Polypropylene Layered-Silicate Nanocomposites
Authors: Yu Suzhu , Liu Songlin , Zhao Jianhong , Xie Hong , Yong Ming Shyan
Published: September 2018

Organoclay reinforced polypropylene (PP) nanocomposites have been prepared by melt intercalation using extrusion. Their structural, rheological and mechanical properties have been investigated. It was found that the organoclays were intercalated and dispersed evenly in the matrix. Both polypropylene and its nanocomposites demonstrated a meltlike rheological behaviour under small-strain oscillatory shear. The storage and loss moduli of the nanocomposites decreased with temperature and increased with organoclay concentration. The effect of temperature and organoclay content on the steady shear viscosity was also studied and a shear thinning behaviour was found at higher shear rates, which facilitated their processing using conventional equipment. The elastic modulus of PP nanocomposites was increased significantly comparing to PP.
Concentration Dependence of Crystalline Poly(L-lactide) Prepared by Freeze-drying Solutions
Authors: Hong Hao , Rongjie Liu , Yaling Zhao
Published: September 2018

Poly(L-lactide) was freeze-dried from p-xylene solutions with varying concentrations. The samples were characterized by differential scanning calorimetry. It was found that the sample produced from the dilute solution exhibited higher non-isothermal crystallization temperature and faster crystallization rate. There was a critical concentration corresponding with the critical overlap concentration proposed by De Gennes in the polymer solutions. In the solution below the critical concentration, the PLLA chains were isolated from each other, resulting in an acceleration of melt crystallization for the recovered samples. It appears that the chain entanglement is a barrier to the melt crystallization of polymer.
Mechanical Properties and Flame Retardancy of SEBS-based Composites Filled with Magnesium Hydroxide
Authors: Xiao Wang-Dong , Kibble Kevin A. , Lin Feng
Published: September 2018

The flame-retardancy and mechanical properties of styrene-ethylene/butylene-styrene block copolymer (SEBS) based composites, containing SEBS blended with a paraffinic hydrocarbon extender oil, copolymer polypropylene (PP), and magnesium hydroxide (MH) or silane coupling agent surface-treated magnesium hydroxide (m-MH) were investigated. A maleic anhydride-grafted SEBS (MA-SEBS) was used as a polymer modifier for some composites. As the amount of MH or m-MH increased, the flame-retardancy of composites improved, while the tensile strength and elongation at break decreased, and the melt property of the composites became worse as well. When the oil-filled SEBS (O-SEBS) was partially replaced by MA-SEBS, the tensile strength of the composites increased, and elongation at break decreased. Furthermore replacing O-SEBS with MA-SEBS and treating MH with silane coupling agent (simultaneously) improved the tensile strength of the composites by a large margin. The phase structure of the composites was characterised using scanning electron microscopy (SEM) and this revealed that the particle-matrix interfacial bonding was improved through the addition of MA-SEBS. The stability of the composites was investigated by thermogravimetric analysis (TGA).
Thermal Characterisation of Short Nylon-6 Fibre-Reinforced NBR Composites
Authors: Rajesh C. , Manoj K.C. , Unnikrishnan G. , Purushothaman E.
Published: September 2018

The thermal behaviour of nylon-6 fibre-reinforced acrylonitrile butadiene rubber (NBR) composites has been studied by thermogravimetry (TG) and differential scanning calorimetry (DSC). The degradation temperatures of fibre-filled composite systems have been observed to be higher than that of NBR. The percentage weight loss at different temperatures during thermal scanning has been found to decrease with fibre loading. Composite samples cured by dicumyl peroxide (DCP) exhibit a higher decomposition temperature compared to the sulfur cured samples indicating that the vulcanisation routes can significantly affect the thermal features of fibre-filled polymer systems. The addition of bonding agents (viz. hexamethylene tetramine-resorcinol and phthalic anhydride) enhances the thermal stability of the composites. The DSC studies indicate that the fibre-filled systems possess higher glass transition temperatures (Tg) than the gum. The composites with added bonding agent show higher Tg compared to the other composite systems, which has been attributed to the stronger interaction between the fibres and the matrix in the former.
Bismaleimide Modified Epoxy-Diallylbisphenol System – Effect of Bismaleimide Nature on Properties
Authors: Devi K. Ambika , Nair C.P. Reghunadhan , Ninan K.N.
Published: September 2018

The properties of the ternary matrix system (EPB), obtained by the reactive blending of epoxy resin - diallyl bisphenol and a bismaleimide, depend on the structure and properties of its components. The influence of the structural variations of bismaleimide on the thermal, physical and mechanical properties of the ternary blend was examined. EPB compositions were prepared using novolac epoxy, diallyl phenol A and three different bismaleimide systems viz. 2, 2-bis 4-(4 maleimidophenoxy) phenyl propane-BMIP, bis (4-maleimidophenyl) methane-BMIM and bis (4-maleimido phenyl) ether-BMIE. The EPB systems with different types of bismaleimides were processed and characterized for their thermal, physical and rheological properties. EPB-glass composites processed using these matrix systems were characterized for their thermo-physical and mechanical properties. High temperature properties of these systems were assessed by their adhesive strength retention at different temperatures. The EPB system formed by the reactive blending of epoxy- phenol system with BMIP was found to yield the blend with improved mechanical performance at ambient conditions, while that with BMIM proved to be the best for high temperature application.
Polycarbonate/Polyamide 6/Nanoclay Ternary Nanocomposite Membranes: Preparation, Characterisation, and Gas Separation Properties
Authors: Gholizadeh B. , Arefazar A. , Barzin J.
Published: September 2018

In this study, polymer membranes were prepared by the solution technique, based on a polycarbonate (PC)/polyamide 6 (PA6) blend, using PC as the matrix phase and PA6 as the dispersed phase. Moreover, nanocomposite membranes were also prepared by the solution technique on the basis of a PC/PA6/nanoclay blend. The permeability of the polymer membranes were calculated using theoretical models. The cross-sectional morphology of the prepared membranes were observed by SEM. The surface roughness of the samples were measured by AFM. XRD was used to analyseanalyzse nanodispersions in the blend. Results showed that the levels of porosity and surface roughness of membranes decreased with increase in PA6 concentration. According to the results of theoretical lingmodelling and the cross-sectional morphology and surface roughness of the membranes, an increase in permeability is expected with increase in PA6 concentration. With the addition of nanoclay to the blend, the degree of porosity and the free volume decreased, and the roughness in the membrane also decreased; in fact, a decrease in permeability is expected when nanoclays are added.
Preparation of TiO2/Polyacrylic Acid and Application in Photocatalytic Degradation of Methyl Orange
Authors: Luo Shanxia , Zhu Hui , Wang Fumin , Xin Feng , Yin Xiaohong
Published: September 2018

TiO2 (P25) fine particles were loaded in a polyacrylic acid (PAA), which possessed a unique absorption characteristic and was synthesised by aqueous solution polymerization. The TiO2/PAA composite was taken as a photocatalyst to degrade methyl orange (MO), the degradability resistance and reproducibility of the photocatalyst were investigated experimentally. The results showed that the TiO2/PAA photocatalyst had a good activity and stability in degradability of organic compound.
Present Status and Key Challenges of Carbon Nanotubes Reinforced Polyolefins: A Review on Nanocomposites Manufacturing and Performance Issues
Authors: Prashantha K. , Soulestin J. , Lacrampe M.F. , Krawczak P.
Published: September 2018

Carbon nanotube reinforcement is a key emerging technology to simultaneously impart enhanced mechanical properties while adding multifunctional characteristics to polymer materials and systems. The promise of extraordinary improvement in-end use properties of polyolefin/carbon nanotube hybrid systems has spurred great interest and intensive activity in academics and industries. This review offers a comprehensive discussion of the preparation, compounding, properties and applications of such nanocomposites. The processing, dispersion and orientation of nanotubes, as well as the characterisation of physical and mechanical properties of carbon nanotube filled polyolefins are discussed. In particular the scientific principles and mechanisms in relation to the methods of manufacturing are highlighted, with an outlook towards commercial applications.
Flexural Characteristics of Concrete Beams Reinforced with a New Type of GFRP Bar
Authors: Oh Hongseob , Moon Do Young , Zi Goangseup
Published: September 2018

Beam tests were conducted to investigate the characteristics of a newly developed type of glass fibre-reinforced polymer (GFRP) rebar as reinforcement in flexural concrete members. Nine beams over-reinforced with different types of rebar, and with varying reinforcement ratios and depths of concrete cover, were monotonically loaded up to failure. Results were characterised by failure mode, moment–curvature, flexural capacity, load–deflection, and crack width. The test results were compared with the theoretical model and the American Concrete Institute design guide, which showed that the performance of the newly- developed GFRP rebar was comparable to commercially available GFRP rebars. In addition, a theoretical model for moment–curvature and an equation for predicting the flexural capacity of the beams with multiple layers of GFRP rebar are presented, based on the experimental observations.
Degradation of Polypropylene and Polyprop/Starch Blends
Authors: Meligi G.A. , El-Rehim H.A. Abd , Ali E. Hegazy A.M. , Rabie A.M.
Published: September 2018

A high-content starch/polypropylene (IPP) blend with acceptable biodegradation and mechanical properties has been produced. IPP/starch (90/10) blends were tested for photo-degradation under the effects of UV sunlight conditions and an artificial UV lamp for periods of time. The influence of irradiation on the degradability of IPP/starch blends was studied by means of its effects on mechanical properties, thermo-gravimetric analysis (TGA and DSC), x-ray diffraction (XRD), and FTIR spectral analysis. The results indicated that the current of the starch amount into the IPP matrix was responsible for the reduction in mechanical properties of the blends, and decreasing in molecular weight of the IPP/starch blend compared with pure IPP.
The Influence of Through-the-Thickness Binder Yarn Count on Fibre Volume Fraction, Crimp and Damage Tolerance within 3D Woven Carbon Fibre Composites
Authors: King R.S. , Stewart G. , McIlhagger A.T. , Quinn J.P.
Published: September 2018

This paper presents a study into the influence of the Through-The-Thickness (T-T-T) binder yarn count on the fibre volume fraction (Vf), crimp and damage tolerance within 3D woven carbon fibre composites. Three fabrics were woven with varying binder yarn counts; the first had 1x12k binders, the second had 2x6k binders (two individual 6k tows laid on top of one another into the structure to form one tow) and the third had 1x6k binder tows.

Dry fabric compress tests conducted on the three 3D woven fabrics showed that a power law can be successful utilised to predict Vf and identify the required pressure to achieve a specific Vf. All three fabrics achieved Vf‘s in the range of 45–47% however the 2x6k binder fabric had higher %CV's compared to the other fabrics. The degree of crimp within the three 3D woven fabrics was shown to be highest within the 1x12k binder fabric followed by the 1x6k binder fabric with the 2x6k binder fabric having the lowest percentage crimp.

Compression after Impact (CAI) tests were conducted and showed that impact depth was significantly influenced by impact location on the T-T-T binders with impact depth differences up to 97% observed. It was shown that impact location and depth played no major role in the CAI strength of the composite. CAI strength was observed to be highest within the 2x6 k binder composite followed by the 1x6k binder composite with the 1x12k composite having the lowest CAI values.
Cure, Mechanical and Solvent Transport Behaviour of Filled Poly(Ethylene-Co-Vinyl Acetate) Composites
Authors: Dasan K. Priya , Unnikrishnan G. , Purushothaman E.
Published: September 2018

The role of fillers such as clay, talc and ZnO on the physical properties of Poly(Ethylene-co-Vinyl Acetate) E VA has been examined. Mechanical properties such as tensile strength and hardness were observed to be the highest for clay filled system followed by talc and ZnO-filled composites. Abrasion resistance of the composites was found to be of the order: clay > ZnO > talc. Among the composites, the clay-filled system showed the lowest solvent uptake and the ZnO-reinforced system the highest. The dielectric constant of the composites was found to be increasing with filler loading. The overall thermal stability of the composites was found to be higher than that of gum EVA.
Surface Functionalisation of Polyester Nonwoven Fabrics by Sputter Coating of Titanium Dioxide
Authors: Xu Yang , Wu Ning , Wei Qufu , Chu Libo
Published: September 2018

Titanium dioxide (TiO2) functional films were deposited on the surface of polyester nonwoven fabrics at room temperature by direct current (DC) reactive magnetron sputtering. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were employed to study the topographies and chemical compositions of the functional fabric surfaces, respectively. Scanning electron microscopy (SEM) was used to investigate the interfacial microstructures and adhesion between the substrate and TiO2 coating. The AFM observations indicated that there was a significant difference in the surface morphology of the polyester fibres before and after TiO2 sputter coating. XPS spectra reflected the chemical features of the deposited TiO2 nanostructures. The SEM images showed that TiO2 thin films deposited on the substrate under confirmed processing conditions had unique, fine surfaces and good adhesion to the substrate. It was found that the deposition of TiO2 on the polyester nonwoven fabrics significantly improved their ultraviolet (UV) absorption and antistatic properties.
Non-Linear Fatigue Fracture Analysis of Composite Laminates
Authors: Rizov V.
Published: September 2018

In this paper, results of an experimental and numerical investigation of the effects of non-linear deformation on the fatigue crack growth in composite laminates are presented and discussed. Mode I fatigue fracture experiments are carried out on extended compact tension specimens under sinusoidal load control at a frequency of 4 Hz. The fatigue fracture test data are analysed using a power law relationship between the crack growth rates and the range of the path-independent J-integral. A two- dimensional finite element model of the extended compact tension specimen is set up in order to compute the J-integral values. The model is coupled with damage analysis in order to study the effect of non-linear deformation on the fatigue fracture performance. The damage analysis is based on the Tsai-Wu failure criterion. The non-linear model is verified by carrying out comparisons between the simulated mechanical behaviour of the extended compact tension specimen and the measured one. The damage distribution within the specimen is analyzed. The J-integral is computed over paths surrounding the crack tip and not crossing the damage zone. It is shown that taking into account the damage behaviour improves the fatigue fracture resistance, which is attributed to increased strain energy dissipation as a result of non-linear deformation.
Hydrophobicity Enhancement of Cellulose-Based Material via Heterogeneous Surface Acetylation
Authors: Zeng Zheng , Ren Wentan , Xu Chi , Lu Weiqiang , Zhang Yong , Zhang Yinxi
Published: September 2018

Heterogeneous cotton fibre surface acetylation with acetic anhydride was performed in an oil bath at 130 °C with Na2CO3 as a catalyst to enhance the reaction activity. The effect of reaction time on fibre acetylation was characterised by the ester content of acetylated fibres, attenuated total reflectance-Fourier transform infrared spectrometry (ATR-FTIR), x-ray diffraction (XRD), static and dynamic contact angle measurements and field emission scanning electron microscopy (FESEM). The ester content increased with increasing reaction time, and the increase of ester content was not evident at a reaction time over 90 min. The emergence and intensity of the absorption peak characteristic of C=O and the reduction of the absorption peak of O-H clearly proved the occurrence of acetylation. The XRD data of the fibres exhibited the typical XRD pattern of cellulose I, and the diffracted intensity decreased after acetylation. Static and dynamic contact angle measurements demonstrated enhanced hydrophobicity and decreased surface energy with increasing reaction time. FESEM micrographs showed that the acetylation removed the wax layer of fibres and smoothed the fibre surfaces.
Development and Evaluation of a Dynamic Mould Temperature Control System with Electric Heating for Variotherm Injection Moulding
Authors: Guilong Wang , Guoqun Zhao , Jitao Liu , Huiping Li
Published: September 2018

Variotherm injection moulding process is a new injection moulding technology. In this process, the mould cavity surface is heated up to a high temperature, before the filling stage, usually higher than the glass transition temperature (Tg) of the polymer. When the filling stage is finished, the shaped polymer melt will be cooled down quickly for mould opening. It is used for producing plastic parts with no weld lines, no flow marks and a shiny surface (up to 98% light reflecting), even for fibre-reinforced plastics. In this study, a new dynamic mould temperature control system with electric heating and coolant cooling for variotherm injection moulding was proposed and studied. The temperature control principle and moulding process for this new technology were explored, and an electric heating mould structure with electric heating rods and cooling channels was developed. The thermal response efficiency of the system and temperature uniformity of the mould surface was also evaluated by transient thermal analysis with a commercial software package, ANSYS. The cooling efficiency of the new variotherm injection moulding was compared with that of conventional injection moulding by calculating the cooling time of the two moulding techniques for plastic parts with different thickness. Finally, an electric heating mould for a 32-inch LCD panel was designed and manufactured, based on the simulation results. With the new proposed dynamic mould temperature control system, a variotherm injection moulding production line for the LCD panel was constructed. The test production results showed that the dynamic mould temperature control systems could efficiently and accurately control the mould temperature. The LCD panels produced with this new variotherm injection moulding process had a high surface gloss, without defects such as weld lines, sink marks, flow marks, etc. which usually occur in conventional moulding.
Incorporation of Silica Nanospherical Particles in Epoxy–Amine Crosslinked Materials II. Dynamic Mechanical Measurements of Epoxy Matrix-Silica Nanocomposites
Authors: León Luis M. , Laza J. Manuel , Torrens Francisco , Puchol Victoria , Abad Concepción , Campos Agustín
Published: September 2018

The mechanical strengths of epoxy composites reinforced with silica nanospheres, unfunctionalised or functionalised with either amine or epoxy groups, increase up to a proportion of 5 wt.% of filler, as reflected in a study of the shear storage modulus carried out in dynamic mechanical analysis. This improvement is observed in both glassy and rubbery states, moderately affecting the glass transition temperature of the material. From this percentage of strengthening substance the mechanical properties begin to deteriorate, but keeping (up to 10 wt.% of strengthening material), a greater storage modulus in shear than that of the pristine epoxy resin. A trend can be discerned as the percentage of filler increases in the nanocomposite, where the materials strengthened with silica nanospheres functionalised with epoxy groups show better mechanical behaviour than the rest. To improve the mechanical properties in the systems, it is important to use an intermediate percentage of strengthening material (not much higher than 5–7 wt.%), the exact proportion depending on the type of strengthening substance.
Manufacturing and Recycling of Sisal-Polypropylene Composites
Authors: Rao S. , Bhattacharyya D. , Jayaraman K. , Fernyhough A.
Published: September 2018

The current study focuses on manufacturing, recycling and mechanical testing of thin (1.5 mm) sisal-PP extruded composite sheets. An 3-factor two-level experimental design based on the Taguchi method was applied in the manufacturing of the composite sheets to maximise their mechanical properties. The sisal-PP composite sheets obtained by setting the factors predicted by the Taguchi analysis were mechanically recycled by pelletising the sheets and feeding through the extruder. The effects of recycling on crystallinity, fibre length, mechanical properties and stress-relaxation were evaluated. By selecting a fibre mass of 30%, polymer MFI of 1.3 g/10 min and 1% of lubricant, ~12%, ~20% and >100% increases in tensile strength, impact strength and tensile modulus respectively were observed. The fibre lengths dropped from 7 mm before extrusion to 6mm and under after extrusion, and under 5 mm after recycling. A marginal change (± 5%) in modulus values was observed in both directions after recycling, the ultimate tensile strength of the recycled sisal-PP specimens dropped down from 41.4 ± 2.5 to 36.4 ± 0.75 MPa along the machine direction, and increased from 19.2 ± 0.5 MPa to 21.4 ± 0.1 MPa transverse to the machine direction mainly due to the decrease in the reinforcing fibre lengths. The recycled composites exhibited greater relaxation compared to the sisal-PP composites; this is because, at higher temperatures, the polymer matrix is in a softened state and the bonding between the fibre and matrix is expected to be weaker and the short fibres behave like polymer rich areas and fail to share the imposed load, thus exhibiting greater relaxation at elevated temperatures.
Diffusion of the Curing Agent through two Epdm Rubber Sheets with Different% Peroxide during their Simultaneous Cure
Authors: Brouzi A. El , Granger R. , Vergnaud J.M.
Published: September 2018

When two sheets of EPDM with different percent peroxide as curing agent, 2% for the one and 10% for the other, are firmly pressed and cured together at a convenient temperature, a transfer of the curing agent has been proved to take place through the interface between these two sheets. The following two facts are observed. On the one hand, when this cured bi-layer system is immersed in toluene, a large swelling is observed but the two layers are not separated, in spite of the different rate and extent of swelling for each EPDM taken separately. On the other hand, the hardness does not vary discontinuously at the interface between the two sheets, but on the contrary it varies continuously through the thickness of the two layer system. This variation of the hardness through the thickness gives an idea of the gradient of peroxide concentration which has been developed during the stage of heating before the onset of cure. The kinetics of absorption of toluene is controlled by diffusion, and the two parameters, with the diffusivity and the capacity of absorption at equilibrium, are evaluated for the two-layer system by using the values measured on the two EPDM components with different percentages of peroxide taken separately. Modelling of the process of absorption and evaporation has been possible from these values for the bi-layer system, explaining the torsion of the bi-layer sheet during the stage of absorption and its stability. An application of this matter transfer during the cure process opens a way for re-treading a truck tyre with a new rubber band.
Preparation, Characterisation and Mechanical Properties of Environmentally Friendly Waterborne Polyurethane and Polyurethane-Acrylate
Authors: Qiu Fengxian , Zhang Jingli , Wu Dongmei , Zhang Qinqin , Yang Dongya
Published: September 2018

The waterborne polyurethane (PU) prepolymer was prepared based on the polyester polyol (N220), isophorone diisocyanate (IPDI), and dimethylol propionic acid (DMPA). The waterborne polyurethane-acrylate (PUA) dispersions were prepared with different proportions of acrylate by in situ dispersion technique. The structures and properties of prepared PU and PUA were analysed and characterised with FT-IR spectroscopy, etc. The results indicated that compared with PU, the PUA dispersions had larger particle diameters, narrower particle-size distribution, lower surface tension, high temperature stability and freeze-thaw stability. The PUA films showed better optical transparency, higher tensile strength and lower elongation at break. The prepared PUA have potential application such as coatings, leather finishing, adhesives, sealants, plastic coatings and wood finishes.
Silver Ion Release from Antimicrobial Acrylate Photopolymer Layers
Authors: Damm C. , Münstedt H.
Published: September 2018

Crosslinked silver-filled acrylate photopolymer layers on polyetheretherketone (PEEK) films were prepared by a heterogeneous photocatalytic polymerisation initiation using silver-coated titanium dioxide as a catalyst material.

The silver ion release from 5 μm thick acrylate photopolymer layers was studied as a function of the chemical structure of the polymer matrix. The silver ion release increases with the number of ethoxy groups per monomer unit, although the filler content in all acrylate samples was the same (2.5 wt.% titanium dioxide coated with 1 mol.% elemental Ag). This finding can be explained on the basis of the water uptake of the polymer matrix: silver ions are generated from elemental silver particles only in the presence of water. The maximum water absorption of the photopolymers as well as the diffusion coefficient of water in the polymers increases with the number of hydrophilic ethoxy groups per monomer unit.

The silver ion release from the acrylate photopolymer layers is governed by diffusion. The diffusion coefficient of silver ions, however, is at least two orders of magnitude smaller than that of water. This finding suggests that the interactions between silver ions and the polymers and/or the titanium dioxide must be stronger than the interactions between water molecules and the polymers and/or the titanium dioxide because the mobility of a diffusing species decreases if the interactions with the surrounding matrix become stronger. Acrylate photopolymer layers containing at least 6 ethoxy groups per monomer unit release an amount of silver ions of 3 μg*l-1*cm-2 or more per day. This amount is sufficient to eliminate Escherichia coli completely within 24 h.
Polystyrene-Carbon Nanotubes Composites Prepared by Microemulsion Polymerization for Vapour Sensors
Authors: Li Qiang , Li Liang , Yan Guoping , Jiang Dengbang , Cheng Zhiyu
Published: September 2018

Polystyrene/carbon nanotubes composites for gas sensor were prepared by microemulsion polymerization and characterized. Because of the in situ microemulsion polymerization, uniform dispersion of carbon nanotubes in the polymer matrix could be obtained more easily and the thermal and electrical properties of the composites were also enhanced, compared with the composites from solution mixing of polystyrene and carbon nanotubes. The response to different organic vapours was evaluated by monitoring the change in the resistance of the composite upon exposure to various gases. It was observed that the composites prepared by microemulsion polymerization showed much better response and reversibility. The change in resistance was of the order of about 103 for the composites prepared by microemulsion polymerization.
Effects of Molecular Weight of Polypropylene on the Correlation between Fracture Toughness and Mechanical/Impact Properties of Gfpp Composites
Authors: Ogazi-Onyemaechi Bernard Chukwuemeka , Leong Yew Wei , Nakai Asami , Kotaki Masaya , Hamada Hiroyuki
Published: September 2018

The accurate prediction of scientific and statistical parameters depends, largely, on the functional correlation between the variables involved, as well as their definite and predictable behaviour around the line of best fit (the regression line). Hence, an accurate and reliable prediction of the fracture toughness and mechanical properties of glass fibre reinforced polypropylene (GFPP) composites is very important in order to prevent sudden failure of components fabricated from them. It also gives the opportunity to save cost on experimentation. Three grades of polypropylene (PP) of different molecular weights (MW) had glass fibre reinforcements each. The incorporation of maleic anhydride grafted PP (MA-g-PP) into the composites was for compatibilisation between the matrix and reinforcements. There was tensile testing on both the un-notched and notched dumbbell samples.

The use of J-Integral analysis was to investigate the fracture toughness of the composites. There was an evaluation of the effect of different MW of PP on the fracture toughness and impact properties of the composites. The examination of the morphology of the materials was by (SEM), while charge coupled device (CCD) camera monitored crack propagation behaviour under tensile loading. There was further morphology study to analyse the fibre length distribution and interfacial shear strength of the composites. Investigations revealed that the composite with the lowest MW PP consistently showed better mechanical, impact and fracture toughness properties than those with higher MW PP. It was also observed that incorporating MA-g-PP as compatibilisers had greater interfacial bonding effects, resulting in higher interfacial shear strength in GFPP of lower MW and high melt flow rates than those of higher MW and low melt flow rate. The investigation further revealed that as the MW of PP decreased, the fracture toughness and other mechanical properties increased in a linear correlation. Crack propagation trailed the interface between PP matrix and GF because of weak bonding in the composite with higher MW PP. This study revealed that incorporating MA-g-PP into GFPP composites achieved better properties with PP of lower MW and higher melt flow rate. Hence the mechanical and fracture properties of GFPP depend largely on the MW of the polymer PP matrix. There was a strong linear correlation observed between the MW of PP, fracture toughness and other impact properties thereby making it possible to make a reliable prediction of any property of the composites from another.
Preparation and Properties of Chloroprene Rubber (Cr)/Clay Nanocomposites
Authors: Cheng Yao-Yi , Yen Ynh-Yue , Kao Peng-Hsiang , Lu Norman , Wang Hsin-Ta
Published: September 2018

Chloroprene rubber (CR)/organic modifier/sodium montmorillonite (NA-MMT) nanocomposites were prepared by melt intercalation. The morphology of the nanocomposites was studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM results showed that the silicate layers of the clay were dispersed in the CR matrix on the nano-scale by adding the organic modifier. X-ray diffraction also indicated that the silicate layers of clay were exfoliated. The mechanical and thermal properties of the nanocomposites could be therefore improved by adding clay and organic modifier, as the silicate layer of the clay was uniformly dispersed. Dynamic mechanical analysis was further performed to investigate the thermomechanical properties of CR–clay nanocomposites containing various amounts of clay. The glass-transition temperature of CR– clay nanocomposites increased with increasing amount of clay and organic modifier.
Polyaniline/Graphite Nanosheets Composites and its Conducting Properties
Authors: Wu Xinming , Qi Shuhua , He Jie , Duan Guochen
Published: September 2018

A facile process for the preparation of polyaniline/graphite nanosheets (PANI/NanoG) composites was developed. Natural flake graphite (NG) was exfoliated into expanded graphite (EG) via an acid intercalation and the NanoG was prepared by treating the EG with sonication in alcohol solution. The composites were fabricated via in situ polymerization of aniline (ANI) monomer in the presence of NanoG. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the structures of NanoG and composites. Results showed that the nanoscale structure of NanoG formed conducting network in PANI matrix. The percolation threshold of PANI/NanoG composites at room temperature was as low as 0.5 vol.%, much lower than that of the PANI/EG (1.6 vol.%) and PANI/NG (1.5 vol.%) composites. Electrical conductivity measurements indicated that the conductivity of PANI/NanoG composites increased greatly compared with PANI/EG and PANI/NG composites.
Effect of Molecular Weight and its Distribution on the Crystalline Morphology of Polypropylene Materials
Authors: Lei H. , Xu T. , Gao C.T.
Published: September 2018

The influence of molecular weight (MW) and molecular weight distribution (MWD) on the variation of crystalline morphology of polypropylene have been investigated. It was observed that neither the number-average molecular weight Mn nor the weight-average molecular weight Mw governs the morphology of the semi-crystalline state of PP materials, but the molecular weight distribution MWD appeared to be the key linear parameter that correlates with the crystalline morphology of the solid state. The dispersion of molecular weight indicates that a synergic effect exists between the high and low molecular weights which will determine the final crystalline morphology of PP materials.
Microstructural Studies of Cement Composites of Thermoplastics
Authors: Nair Priya S. , Thachil Eby T.
Published: September 2018

Studies of the microstructure of polymer cement composites provide information regarding the topography, leachability of the water-soluble components within and the nature of interactions between the polymer and cement particles. These enable in optimizing the macroscopic properties and also in the preparation of tailor-made composites for a given application. This paper makes an attempt to explain the morphology and nature of interactions between the cement particles and thermoplastics in polymer cement composite. All the thermoplastics in this study were added to the cement paste either as water solutions or emulsions with calcium chloride as an accelerator for hydration of the cement particles. Thermal analysis, soxhlet extraction and scanning electron micrographs (SEM) were some of the techniques employed to investigate the microstructure. The analysis obtained from the above revealed that the thermoplastics formed a film around the cement particles thereby preventing the leaching of the water-soluble components which were present in the cement matrix. Since the polymers are added to the cement before cement hydration some of the polymers undergo interactions with the cement resulting in the formation of chemical bonds between the two phases. This results in better durability properties when the composites are exposed to polluted chemical environments.