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Polymers and Polymer Composites

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Title: EFFECT OF INJECTION SLOT LOCATION ON DIE-DETACHED TAPERED INJECTION CHAMBER IN RESIN INJECTION PULTRUSION
Page Range: p.513-526
Author(s): Jeswani A L; Roux J A
File size: 723K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
This study seeks to continuously improve the wetout and thus the quality and productivity of pultruded parts for the tapered injection pultrusion process for an injection chamber 'detached' from the pultrusion die. Complete wetout of the dry fibre reinforcement by the liquid resin depends strongly on the axial location of the injection slot within the injection chamber. This investigation was conducted for a high pull speed with a fibre volume fraction and resin viscosity for a nominal polyester/glass roving composite. A 3-D finite volume technique was developed to simulate the flow of polyester resin through the glass rovings. The results show the impact of the axial location of the injection slot on the minimum injection pressure necessary to achieve complete fibre matrix wetout and the resin pressure within the injection chamber for a tapered injection chamber which is 'detached' upstream of the pultrusion die. Injection chamber design information is presented. 18 Refs.

Title: CHARACTERIZATION AND MODELLING OF HYGROTHERMAL EFFECTS IN THERMOPLASTIC NANOCOMPOSITES
Page Range: p.527-542
Author(s): Samit Roy; Kameshwaran Narasimhan
File size: 667K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
The hygrothermal and mechanical characterisation of continuous fibre-reinforced nanocomposites in compression moulded E-Glass fibre-reinforced in polyamide-6 or nylon-6 matrix with and without different weight addition of nanoclay have been performed. E-Glass/Nylon-6 nanocomposite was characterized by means of X-Ray Diffraction to determine the nanoclay dispersion morphology. Significant improvement were achieved in compressive strength, shear strength and barrier properties with relatively low nanoclay loadings. The baseline and nanoclay modified E-Glass/Nylon-6 specimens were immersed in de-ionized water at 50 degrees C and aged hygrothermally. Mechanical tests on unaged E-Glass/Nylon-6 nanocomposite confirmed strength enhancement with nanoclay addition, with a significant improvement in compressive strength (50% at 4 wt.% nanoclay loading) and shear strength (~36% at 4 wt.% nanoclay loading). Mechanical tests on hygrothermally aged E-Glass/Nylon-6 modified with 4 wt.% nanoclay loading showed that hydrothermal degradation is drastically reduced with a significant reduction (~30%) in moisture uptake compared to baseline E-Glass/Nylon-6 composites. An analytical model is developed to capture the diffusion mechanism and attribute the change in diffusivity and moisture uptake with weight addition of nanoclay to tortuosity and reduction in free volume created by the presence of nanoclay. The loss in change in free volume computed using Atomic Force Microscopy images is compared with analytical model. 30 Refs.

Title: DAMAGE MECHANISMS IN HEMP-FIBRE WOVEN FABRIC COMPOSITE, AND COMPARISON WITH GLASS-FIBRE COMPOSITE
Page Range: p.543-552
Author(s): Bonnafous C; Touchard F; Chocinski-Arnault L
File size: 595K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
This paper deals with hemp-fibre and glass-fibre woven fabric/epoxy composites. The aim is to analyse damage mechanisms in these composites by comparing three different methods: acoustic emission, microscopic observations and stiffness loss measurement. For acoustic emission (AE), an experimental multi-scale analysis was developed in order to identify the different damage mechanisms. Tensile tests were performed on single yarn, neat epoxy resin and composite materials to determine their AE amplitude signatures. A statistical analysis of AE amplitude signals was realised and correlated with microscopic observations. This study has enabled to identify the amplitude and to track, during tensile tests, three types of damage in these composites: matrix cracking, interfacial debonding and reinforcement fracture. It shows the different processes of damage development in natural fibre reinforced composites, in comparison with glass fibre composites. These results were compared to the measured stiffness loss of composites. It allows one to highlight the difficulty to link this mechanical damage parameter with physical AE events. 35 Refs.

Title: LOW ENERGY IMPACT INDENTATION OF AN EPOXY-CARBON FIBER LAMINATE
Page Range: p.553-558
Author(s): Martinez A B; Xiang G; Arencon D; Velasco J I
File size: 432K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
The impact event involves the motion of the specimen, the motion of the striker and the local indentation in the contact zone. In order to study the effect of the local indentation, epoxy-carbon fibre laminate specimens supported on a very rigid steel plate, were subjected to low energy impacts in an instrumented falling weight dotted with an instrumented striker with an hemispherical head. The obtained restitution coefficients show that the energy absorption by indentation is not negligible. It has been developed a lumped mass spring model based in the Hertz law which agrees with the experimental contact forces, indenter displacements and restitution coefficient, which give a very good fitting. This non-conservative model allowed assessment of the Young's modulus at these relatively high strain rates. 8 Refs.

Title: ENVIRONMENTAL DEGRADATION OF STARCH/POLY(LACTIC ACID) COMPOSITE IN SEAWATER
Page Range: p.559-566
Author(s): Xiaolei Chen; Lumin Wang; Jiangao Shi; Hang Shi; Yongli Liu
File size: 324K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
In order to study the degradation property of starch/polylactic acid (PLA) composites in a briny environment, injection-moulded tensile bars of starch/PLA composites were investigated by immersion in static seawater controlled at 25 degrees C for 1 year. SEM micrographs showed that starch particles were lost from the bar because of microbial action. GPC results showed the number average molecular weight (Mn) of PLA decreased with degradation time. The glass transition temperature (Tg) and melting temperature (Tm) measured by DSC decreased slightly with degradation time. An increase of crystallinity calculated from the DSC data was attributed to the decrease of molecular weight. Weight losses were mainly due to loss of starch. The impact strength of the composites decreased monotonically with degradation time; tensile strength and elongation at break of the composites first decreased, then increased and at last decreased again with degradation time, and the water was acting as a plasticiser. The starch/PLA composites in seawater had degradability, but the degradation rate of composite bars studied in this paper was very slow. 23 Refs.

Title: THE INFLUENCE OF THE EXTRUSION TEMPERATURE ON THE MECHANICAL PROPERTIES OF MMT FILLED PA 6 COMPOSITE
Page Range: p.567-572
Author(s): Meszaros L; Olah L; Ronkay F; Czvikovszky T
File size: 383K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
Effects of varying extrusion temperatures on the mechanical properties of polyamide 6 (PA 6) matrix montmorillonite (MMT) filled composites were investigated in this paper. Five different temperature programs were used for producing composites with 1 wt.% nanoparticles content. The mechanical properties were evaluated by tensile and flexural tests and SEM pictures were taken from the fracture surfaces. X-ray diffraction patterns were also measured to obtain some information about the structures of the materials. The results showed that the lower extrusion temperatures resulted in better mechanical properties of the composite. 13 Refs.

Title: CHARACTERIZATION OF CHITOSAN-HYALURONIC ACID BLENDED MEMBRANES AND THEIR EFFECTS ON THE GROWTH OF KERATOCYTES
Page Range: p.573-580
Author(s): Zi-Ang Yao; Hai-Ge Wu
File size: 523K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
In order to construct a suitable scaffold for corneal cell culture and transplantation in vitro, various chitosanhyaluronic acid blended membranes were prepared, and the properties of the blended membranes were studied. Rabbit keratocytes were seeded onto the blended membrane surfaces and the effects of the blended membranes on cell attachment and metabolism were investigated. The results showed that chitosan and hyaluronic acid (HA) were compatible in blended membranes. HA improved the homogeneity, crystallisation and transparency, and decreased the tensile strength and hydrophilicity of blended membranes within the blending ratio of 1:0.05. Under the blending ratio of 1:0.02, HA reduced the harm that the chitosan membrane caused the cells and improved the biocompatibility between cells and membranes. Rabbit keratocytes grew and formed a confluent monolayer on the chitosan-hyaluronic acid blended membrane within a blending ratio of 1:0.02. All the results indicated that chitosan and HA were compatible within the blending ratio of 1:0.02, and the blended membranes had homogeneous structure, suitable physicochemical properties and biocompatibility with cells, this implied that the blended membranes could be used as a scaffold for corneal cell culture in vitro and as a potential carrier for corneal endothelial cell transplantation. 14 Refs.

Title: A KINETIC MODEL OF ALKALI CATALYZED PHENOL-FURFURAL NOVALAC RESINIFICATION
Page Range: p.581-586
Author(s): Sanjeev Ahuja; Daljit Singh
File size: 289K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
In this paper, experimental studies were carried out on the preparation of phenol-furfural novalac resins in the presence of potassium carbonate catalyst with a wide range of furfural to phenol (F/P) mole ratios in the feed. A reaction scheme, applicable to alkali catalyzed phenol-furfural novalac resins, was postulated. A model was developed by the lumping of the different reactivities of the sites of phenol into their functionalities. The effects of the mole ratio of the reactants and the functionality of the phenol on the rate constant were examined. 19 Refs.

Title: PHOTOPOLYMERIZATION OF BIS(4-METHACRYLOYLMETHYLPHENYL)SULFIDE AND BIS(4-METHACRYLOYLMETHYLPHENYL)SULFONE WITH VINYL MONOMERS AND PROPERTIES OF THE PREPARED COPOLYMERS
Page Range: p.587-592
Author(s): Wieslaw Rudz; Gawdzik B
File size: 232K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
The reaction of photopolymerisation of bis(4-methacryloylmethylphenyl)sulphide (BMcMPhS) and bis(4methacryloylmethylphenyl)sulphone (BMcMPhSu) with the typical vinyl monomers: methyl methacrylate (MMA) and styrene (St) in the presence of the two photoinitiators: Irgacure 651 and Darocur 1173 are presented. The influence of percentage concentration of BMcMPhS and BMcMPhSu on the gelation times of the prepared copolymers was studied. The effect of the used photoinitiator concentrations on gelation times was also investigated. For the chosen copolymers, mechanical properties including tensile strength, elongation at break, Young modulus, Brinell's and Shore's hardness were determined. The results showed that copolymers with MMA had shorter gelation times than those with St. Gelation times were shorter when Darocur 1173 was used as a photoinitiator. An increase of Darocur 1173 concentration caused a decrease of gelation times, whereas in the case of Irgacure 651 the opposite relation was observed. 26 Refs.

Title: REINFORCED RUBBER WITH IONIC LIQUID MODIFIED CARBON BLACK
Page Range: p.593-602
Author(s): Yanda Lei; Baochun Guo; Xiaoliang Liu; Demin Jia
File size: 464K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
The ionic liquid, 1-butyl-3-methylimidazole hexafluorophosphate (BmimPF6), was utilized to modify carbon black (CB) via microwave (MW) irradiation. The conditions for the preparation of the modified CB (m-CB) were optimized. The reinforceability of the m-CB in styrene-butadiene rubber (SBR), butadiene rubber (BR) and nitrile rubber (NBR) composites were evaluated. The curing behaviour, morphology and tensile properties of the rubber/m-CB composites were studied and compared with those of composites filled with unmodified CB. Rubber/m-CB compounds showed a significant increase in the curing rate for a generated zinc complex with the alkylimidazoles. Compared with CB, m-CB exhibited a significantly improved reinforceability of the rubbers at lower filler loading, although the mechanical properties were changed slightly at higher filler loading. A possible mechanism was proposed, based on the molecular slippage theory in which the interfacial bonding, the filler loading and the chain flexibility of the rubber molecules were all considered. 43 Refs.

Title: RHEOLOGY, MORPHOLOGY AND MECHANICAL PROPERTY RELATIONSHIP OF NON-HALOGEN FLAME RETARDED GLASS FIBRE REINFORCED POLYAMIDE 66
Page Range: p.603-610
Author(s): Liping Li; Bin Li
File size: 394K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
In this study, the rheological behaviour of polyamide 66 (PA 66) composites consisting of flame retardant (FR)MPP, glass fibre (GF) was characterized with a capillary rheometer at different shear rates. The effect of the shear rate on the viscosity and flow curve was discussed in terms of the power law index for non-Newtonian flow. The effect of the loading level of flame retardant on the rheological properties was studied. The results showed that MPP modified the interfacial interaction between PA 66 and glass fibre. The PA 66/GF/MPP composite behaviour as shear thinning flow under the experimental conditions was investigated, and the investigation of activation energy showed that the proper processing temperature was 275 degrees C for PA 66/GF/MPP. The morphology of the samples observed by scanning electron microscopy was consistent with the predictions from rheological results. The influence of rheology and morphology on the mechanical properties was also examined. It was found that mechanical strength of the composites was improved within a certain range of contents. 17 Refs.

Title: SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF AMPHIPHILIC COPOLYMER DERIVATIVES
Page Range: p.611-618
Author(s): Yongxiao Bai; Yaobin Liu; Yanfeng Li; Caiping Chang; Qi Zhang
File size: 397K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
A series of antimicrobial amphiphilic quaternised copolymers are synthesised through glycidyl methacrylate and styrene after poly(glycidyl methacrylate-co-styrene) modified by introduction of chloroethylic groups using chloroacetyl chloride. The antimicrobial activity of the obtained copolymers was evaluated against the gram-negative bacteria Escherichia coli, the gram-positive bacteria Bacillus subtilus, Staphyloccocus aureus Rosenbach and the fungus Monilia albican by the cut-plug method and Luria-Bertani broth suspended method. The research showed that the copolymer with the molar ratio of monomers 30:70 was the most effective against the microorganisms. The minimum inhibitory concentration (MIC) values of the polymer with against Staphyloccocus aureus Rosenbach and Monilia albican were found to be 31.3 and 32.1 (mu) g/mL, respectively, and these copolymers did not have any haemolytic action for mammalian erythrocytes. 36 Refs.

Title: THEORETICAL AND EXPERIMENTAL INVESTIGATION ON HELIUM LEAKAGE CHARACTERIZATION OF FLEXIBLE FILM-FABRIC LAMINATED COMPOSITES
Page Range: p.619-624
Author(s): Xue Feng Yao; Qing Wu; Chao Xiong; Pin Jing Wen; Hui Feng Tan
File size: 349K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 19
Issue No: No.7

Abstract
Flexible film-fabric laminated composites with low-density and high-performance are important envelope materials in stratosphere aerostats. In this paper, a multilayer leak model is used to predict the helium leak rate of the virgin samples by the Fick's law, which shows a good agreement with experimental data. The influences of mechanical damage, ultraviolet radiation and intense ozone corrosion on the Young's modulus and the permeability of envelop materials are investigated in experiment, which are confirmed by means of damage-induced helium leakage models. Finally, helium leakage mechanisms of flexible film-fabric laminated composites are analyzed. 9 Refs.

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