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Polymers and Polymer Composites

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Title: MICROSTRUCTURAL EFFECTS ON DAMAGE BEHAVIOUR IN PARTICLE REINFORCED COMPOSITES
Page Range: p.1-8
Author(s): Kwon Y W; Liu C T
File size: 262K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 11
Issue No: No. 1

Abstract
A discussion is presented on the effects of non-uniform, random particle distribution on damage initiation and growth, leading to short cracks and breakage of particle reinforced composite specimens. Damage was described a the micro-level, and results were compared qualitatively and quantitatively with experimental observation, with good agreement. It was found that non-uniform, random particle distribution yielded sporadic crack initiation and growth within a uniform tensile specimen. No local crack propagated beyond a certain size, and breakdown of the specimens was not caused by the continuous growth of a single critical crack. Rather, it is maintained, coalescence of neighbouring sporadic short cracks resulted in the breakage of the specimens. The use of computer simulation demonstrated that random particle distribution affected the strength of the composite, but not its effective stiffness. However, a pre-existing crack in the specimen before loading, the effect of the random particle distribution on the initial crack and strength of the composite proved to be near negligible. 13 refs.

Title: INVESTIGATION OF OIL PALM AND PINEAPPLE FIBER REINFORCED PHENOL FORMALDEHYDE COMPOSITES BY ACOUSTIC EMISSION TECHNIQUE
Page Range: p.9-18
Author(s): Sreekala M S; Czigany T; Romhany G; Thomas S
File size: 344K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 11
Issue No: No. 1

Abstract
Several types of oil palm and pineapple fibre reinforced phenol formaldehyde composites were investigated by fracture mechanics and acoustic emission response. It was found that the fracture behaviour was influenced by the fibre content, the length of the fibres and the condition of the fibre-matrix interface. Single edge-notched tensile specimens were cut from composite plates and examined, and the fracture toughness was determined from force-elongation curves. Results showed that the failure mode for untreated and treated fibres varied, and that surface treatment of the fibres was more important than the fibre content. 9 refs.

Title: SYNTHESIS OF GRAFT COPOLYMERS OF ACRYLAMIDE AND COMONOMERS ON TO CELLULOSE: A STUDY OF THE EFFECT OF COMONOMER ON POLYMER YIELDS, STRUCTURE AND PROPERTIES
Page Range: p.19-30
Author(s): Chauhan G S; Guleria L; Lal H
File size: 211K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 11
Issue No: No. 1

Abstract
This work reports on the grafting of acrylamide alone onto cellulose extracted from pine needles, as well as in the form of its binary monomer mixture with acrylic acid, hydroxyethyl methacrylate, glycidyl methacrylate, and acrylonitrile, using benzoyl peroxide as a free radical initiator. Optimum grafting conditions of acrylamide onto cellulose (concentrations of initiator and monomer, reaction time and temperature, and amount and composition of the solvent system) have been evaluated and the same grafting conditions have been used for comonomers to be grafted separately with acrylamide using five different concentrations of comonomer. Graft copolymers are characterised by SEM, FTIR, and thermal analysis techniques. Grafting of acrylamide onto cellulose enhances the hydrophobicity of the backbone, providing a novel reactive polymeric material for use in separation and enrichment applications. As such, the study provides a basis for the synthesis of graft copolymers for speciality applications. 18 refs.

Title: EFFECT OF A TWO STEP FIBER TREATMENT ON THE FLEXURAL MECHANICAL PROPERTIES OF SISAL-POLYESTER COMPOSITES
Page Range: p.31-36
Author(s): Calado V; Barreto D W; d'Almeida J R M
File size: 72K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 11
Issue No: No. 1

Abstract
Sisal fibres were chemically treated with a two-step treatment involving immersion in a sodium sulphide aqueous solution, followed by an acetic anhydride/acetic acid mixture, in order to promote better adhesion to a polyester resin matrix. The flexural properties of the composites was analysed as a function of the time of immersion in distilled water. The results show that the chemical treatment improved the fibre/matrix interaction as revealed by the brittle behaviour of the composites reinforced with the treated fibres, and also improved the composite behaviour in relation to moisture. The long term behaviour of the composites exposed to water was however, not improved, which could be due, it is proposed, to the controlling role of plasticisation of both the fibres and the resin matrix for the longer times of immersion. 29 refs.

Title: USE OF AMMONIUM SALTS OF OLIGOSULPHONIC ACIDS AS FLAME RETARDANTS FOR POLYMER COMPOSITIONS
Page Range: p.37-50
Author(s): Karaivanova M S
File size: 164K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 11
Issue No: No. 1

Abstract
This work studies the effects of the ammonium salts of N- and Br-N-containing sulphonic acids as fire retardants on the flammability characteristics of both polychloroprene and ethylene-propylene rubbers for use in the manufacture of fire resistant cable insulation and conveyor belting respectively. The investigated organic additives were proved to act as flame retardants, smoke reducing agents and thermal stabilisers in these compositions. When combined with Sb2O3, these additives show synergism and their action occurs in the gaseous phase on combustion. 51 refs.

Title: ORIENTATION EFFECT IN POLY (BUTYLENE SUCCINATE) FIBRES
Page Range: p.51-56
Author(s): Nakayama K; Masuda T; Cao A; Vega-Baudrit J; Pereira R
File size: 126K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 11
Issue No: No. 1

Abstract
To investigate the biodegradation mechanism of aliphatic polyesters such as polybutylene succinate, fibres of polybutylene succinate were prepared using a single-screw extruder at various take-up speeds. Changes in fibre structure, morphology and physical properties were investigated using sonic velocity measurements and X-ray diffraction. High take-up speeds were shown to enhance some of the properties of polybutylene succinate fibres as a consequence of changes in molecular orientation and crystallinity. Spherulites of polybutylene succinate were also obtained at 90 degrees C. 5 refs.

Title: STUDY OF POLYAMIDE-IMIDE RESIN/COPPER FOIL COMPOSITE MATERIALS
Page Range: p.57-67
Author(s): Chou S; Lee K-S
File size: 352K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 11
Issue No: No. 1

Abstract
In this research, monomers such as 3,4'-oxydianiline (3,4'-ODA) and p-aminobenzoic acid were used to synthesise a high temperature resistant polyamide-imide resin, and the NHCO (amide) group was introduced into the molecular chain to improve the resin's melt flow, solubility and adhesion. Also, without using any coupling agent, two layers of copper foil laminate were formed by hot press gluing. Tests for void content, moisture content, adhesive bond moisture resistance, heat and chemical resistance, dielectric constant, dissipation factor, and surface analysis were carried out to evaluate the properties of the laminates for heat resistant, high performance applications. 13 refs.

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