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Polymers and Polymer Composites

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Title: ANALYTICAL SOLUTION FOR COHESIVE LAYER MODEL AND MODEL VERIFICATION
Page Range: p.741-752
Author(s): Roy S; Yong Wang
File size: 178K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 8

Abstract
The objective of this work was to find a solution to the cohesive damaged zone that may occur at the interface between a fibre reinforced polymer plate and concrete structure, when considering elastic deformation in the substrate. The structure incorporates a structural adhesive. The work aims to provide data to be used in civil engineering applications such as infrastructure retrofit and repair. For this purpose, the procedure was that a two-dimensional cohesive layer constitutive model with a prescribed traction-separation law was constructed from basic principles of continuum mechanics. Detailed benchmark comparisons of analytical results with finite element predictions for a double cantilever beam specimen were performed for model verification, and issues related to cohesive layer thickness were investigated. It was observed that the assumption of a rigid substrate in analytical modelling could lead to inaccurate analytical prediction of the cohesive damage zone length. 10 refs.

Title: TRANSPORT AND FLAME PROPERTIES OF NATURAL FIBRE REINFORCED POLYMERS
Page Range: p.753-764
Author(s): Torres F G; Flores R; Dienstmaier J F; Quintana O A
File size: 349K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 8

Abstract
The thermal conductivity, water absorption and linear burn rate of sisal fibre-reinforced HDPE and degradable starch-based polymers were investigated. The effect of fibre content, moisture and void fractions on the thermal conductivity was studied. From the water absorption tests, it was determined that water diffusion in natural fibre-reinforced plastics corresponded to a Fickian process only in the early stages of diffusion. Diffusivities were obtained for that case. Linear burn rate experiments showed that sisal reinforced polymers burned twice as fast as unreinforced HDPE specimens. The reinforced specimens, however, showed better structural integrity during burning than the unreinforced ones, probably due to an increase in viscosity and melt strength, because of the presence of reinforcing fibres. 39 refs.

Title: YIELD BEHAVIOUR OF RUBBER-MODIFIED EPOXY ADHESIVES UNDER MULTIAXIAL STRESS CONDITIONS: EFFECT OF PLASTIC DEFORMABILITY OF THE MATRIX PHASE
Page Range: p.765-776
Author(s): Imanaka M; Yamashita D; Suzuki Y; Fujinami A
File size: 428K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 8

Abstract
In this study, the effect of plastic deformability of the matrix phase on the yielding behaviour of the rubber-modified epoxy adhesives was examined. Yield behaviour was measured by use of butt and scarf joints subjected to tensile loading, and to a butt joint with a thin-walled tube subjected to torsional loading. A reactive diluent was used to vary the plastic deformability of the matrix phase. The applicability of Gurson's model was checked by comparing the experimentally-obtained yield stresses in these joints with those calculated by a finite element method. As a result, it was confirmed that the yield stress of the rubber-modified adhesives with different matrix phases could be approximately estimated from Gurson's model. Thus, the effect of plastic deformability of the matrix phase on Gurson's parameter could be discussed. 13 refs.

Title: PREPARATION AND PROPERTIES OF THERMOPLASTIC POLYAMIDE-IMIDE AND POLYUREA-AMIDE-IMIDE/COPPER FOIL COMPOSITES
Page Range: p.777-794
Author(s): Meng-Shun Huang; Ming-Chien Yang; Shen Chou
File size: 258K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 8

Abstract
Polyimides are used extensively in printed circuit boards, but their applications have been limited due to their high softening temperatures and their insoluble nature in most organic solvents. Polyamide-imide and polyurea-imide resins have been developed to overcome these disadvantages. They include amide and urea groups respectively in their main chains to improve solubility and adhesion. In this paper, polyamide-imide (PAI) and polyurea-amide-imide (PUAI) resins were polymerised from five reactants: 4,4'-oxydianiline, 4-nitrobenzoyl chloride, 4,4'-diphenylmethane diisocyanate, 1,2,4,5-benzenetetracarboxylic dianhydride, and 3,3'-4,4'-benzophenone tetracarboxylic dianhydride. Their chemical structures were characterised using elemental analysis, FTIR and high nuclear magnetic resonance. Thermal properties, adhesive properties, electrical properties, heat resistance, and chemical resistance were also studied. Results indicate the suitability of these materials for use in the manufacture of flexible printed circuit boards. 20 refs.

Title: THE EFFECT OF POLYETHYLENE-OCTENE ELASTOMER ON THE MORPHOLOGICAL AND MECHANICAL PROPERTIES OF POLYAMIDE 6/POLYPROPYLENE NANOCOMPOSITES
Page Range: p.795-805
Author(s): Wahit M U; Hassan A; Ishak Z A M; Bakar A A
File size: 359K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 8

Abstract
The aim of this research is to strike a balance of stiffness, strength and toughness in polyethylene-octene elastomer- (POE-)toughened PA6/PP nanocomposites, using the weight ratio of PA6/PP 70:30. For this purpose ,the effect was investigated of POE concentration on the tensile, flexural, and Izod impact properties and on the morphological aspects of the blends. The fracture toughness was also measured. While the tensile and flexural properties were found to decrease with the increasing concentration of POE, the toughness was found to be significantly enhanced as compared to the neat PA6/PP blends. 32 refs.

Title: POLY(2-HYDROXY ETHYL METHACRYLATE-CO-ACRYLIC ACID) AS NOVEL BIODEGRADABLE MACROPOROUS HYDROGEL
Page Range: p.807-814
Author(s): Mohapatra R; Swain A K; Mohapatra R; Rana P K; Sahoo P K
File size: 202K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 8

Abstract
The main purpose of this work was to develop a new copolymer hydrogel, poly(2-hydroxy ethyl methacrylate-co-acrylic acid(P(HEMA-co-AA) with a crosslinker, MBA, because of its future prospects in drug delivery. The structure of the copolymer was characterised by FTIR, H-NMR and SEM, and its thermal stability was investigated by thermogravimetric analysis. Its hydrogel character was observed by studying the swelling of the copolymers by measuring weight gain and loss. The biodegradability of the copolymers was studied by introducing microbes into the culture media along with the prepared sample, and it was verified by examining the surface morphology by SEM. The rate of biodegradation was monitored by the carbon dioxide release method. Results indicated that the copolymer as suitable for implementation in various drug delivery systems and in the manufacture of medical devices for diagnostic purposes, because of its hydrogel character and inter-communicating macropores, along with its high thermal stability. 36 refs.

Title: PREPARATION OF NBR/EXPANDED GRAPHITE NANOCOMPOSITES BY SIMPLE MIXING
Page Range: p.815-821
Author(s): Liu D W; Du X S; Meng Y Z
File size: 145K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 8

Abstract
This article reports on the synthesis of elastomer/expanded graphite nanocomposites by melt mixing. The properties of the resulting nanocomposites and the nanoscale dispersion of the graphite sheets within a NBR matrix are investigated and discussed. The mechanical properties of the NBR/EG nanocomposites showed a remarkable improvement in tensile strength, it is reported. Dynamic mechanical analysis showed that the expanded graphite imparted a higher storage modulus and lower glass transition temperature to the NBR matrix. The expanded graphite was also shown to be effective in increasing the electrical conductivity of the composites. 16 refs.

Title: THE CONSTRUCTION AND ANALYSIS OF A PREDICTION MODEL FOR COMBINING THE TAGUCHI METHOD AND GENERAL REGRESSION NEURAL NETWORK FOR INJECTION MOULDING
Page Range: p.823-829
Author(s): Chung-Feng Jeffrey Kuo; Yung-Chang Li; Yi-Shiuan Wu
File size: 154K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 8

Abstract
In order to avoid dimensional errors after the injection moulding process, processing parameters are established to effectively provide dimensional control. In this work, particular attention is given to reducing the dimensional error in the hexagonal screw diameter when processing engineering plastics such as PEEK, and to also improve the quality of the polymer. Factor levels were chosen according to the chosen quality characteristics, and a prediction model for the injection process was constructed using the Taguchi quality method and a general regression neural network. The optimum conditions determined by the Taguchi method could be modified by the neural network. It was thus demonstrated that the injection moulded product could achieve reduced dimensional errors by adjusting the factor levels using this combined approach. 11 refs.

Title: POLYAMIDOAMINE (PAMAM) DENDRIMERS IN DYE DECOLORISATION. BRIEF COMMUNICATION
Page Range: p.831-833
Author(s): Cheng Yiyun; Fu Rongqiang; Xu Tongwen
File size: 69K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 8

Abstract
This article reports on an investigation of the ability of polyamidoamine (PAMAM) dendrimers to decolourise dye solutions, as exemplified by the triarylmethane dye known as Water blue. PAMAM solutions were prepared and Water blue was dried in a hot air convection oven. Various volumes of PAMAM solution were added to dye solutions and distilled water was added to make a total volume of 60 mL. Following equilibration, the samples were centrifuged and visible light absorbances were determined by a UV-Vis spectrophotometer in order to trace the progress of decolourisation. It was found that PAMAM dendrimers could effectively decolourise this type of dye and that it was also possible to increase the dye decolourising activity of PAMAM dendrimers by selection of the optimal conditions. The highest colour removal efficiency was 99.3%. Colour removal was most effective when the test solutions were at a high pH level (over 7). 5 refs.

Title: THE CURE AND THERMAL BEHAVIOUR OF MG(OH)2/EPOXY RESIN/DEEA NANOCOMPOSITES PREPARED BY A NOVEL METHOD. BRIEF COMMUNICATION
Page Range: p.835-838
Author(s): Cheng Yiyun; He Pingsheng; Cui Ronghui
File size: 111K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 8

Abstract
Magnesium hydroxide is a smoke-reducing and non-toxic additive that has been extensively used in halogen-free flame retardant polymeric materials. However, it's low flame retardant efficiency and the very high loadings that are consequently required when used in its ordinary form, lower the mechanical properties of a flame-retarded polymeric composition. It has been reported that nanosized magnesium hydroxide/polymeric compositions have the potential to solve such problems due to the mechanically reinforcing and flame retardant functions of nanosized composite materials. This study reports on the cure and thermal behaviour of these epoxy resin/magnesium hydroxide composites. The results of tests indicate enhanced thermal stability. This is claimed to be partly attributable to the prevention of out-diffusion of the volatile gas from the thermally decomposed particles, because magnesium hydroxide nanoparticles, when well-dispersed in epoxy networks, act as gas barriers, reducing the permeability of the volatile gas. 10 refs.

Title: PREPARATION AND CHARACTERIZATION OF NIČ+-MONTMORILLONITE/POLYVINYL ALCOHOL WATER-SOLUBLE NANOCOMPOSITE FILM
Page Range: p.839-846
Author(s): Li-Ping Wang; Yun-Pu Wang; Fa-Ai Zhang
File size: 133K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 8

Abstract
This paper describes the preparation of a new type of water-soluble nanocomposite film from polyvinyl alcohol, NiČ-montmorillonite (NiČ-MMT), a defoaming agent, a levelling agent, and a plasticiser. Its thermal characteristics were studied by DSC, and the intermolecular interactions were measured by FTIR and XPS. The tensile strength and elongation at break were also measured. The microstructures were studied by XRD and AFM. FTIR and XPS spectra indicated that crosslinking had taken place between PVA and NiČ-MMT. XRD and AFM indicated that the PVA molecules had inserted themselves into the silicate layers of MMT, exfoliating them and dispersing them randomly into the PVA matrix. Compared to pure PVA film, the tensile strength of the films increased and the elongation at break decreased when the NiČ-MMT was added and the dissolution temperature of the film was also reduced. 23 refs.

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