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Polymers and Polymer Composites

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Title: THERMAL DEGRADATION OF POLYURETHANE BICOMPONENT SYSTEMS IN CONTROLLED ATMOSPHERES
Page Range: p.1-26
Author(s): Ketata N; Sanglar C; Waton H; Alamercery S; Delolme F; Raffin G; Grenier-Loustalot M F
File size: 353K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 1

Abstract
The thermal behaviour of bicomponent polyurethanes in conditions of controlled atmosphere and temperature was characterised by determining their heat stability using on-line TGA/FT-IR coupling and off-line TGA/TCT/GC/MS coupling in order to identify the volatile compounds released. Degradation residues were analysed by FT-IR and MALDI-TOF mass spectrometry. A major disadvantage of these thermoplastic elastomers is that one of the components, isocyanate, is toxic. Based on the data obtained with model urethane compounds (para-TI-based) and bicomponent polyurethane polymer (MDI and PEG-based), this paper demonstrates that the thermal degradations are different. Since the various applications to which these materials are applied and the fact that they are exposed to extreme working conditions, reaction mechanisms for their degradation are proposed. 47 refs.

Title: HYDROTHERMAL AGEING OF GF/PP COMPOSITES: WHEN GLASS/POLYMER ADHESION FAVOURS WATER ENTRAPMENT
Page Range: p.27-35
Author(s): Lariviere D; Krawczak P; Tiberi C; Lucas P
File size: 173K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 1

Abstract
The aim of this paper is to investigate the effects of hydrothermal ageing on the mechanical behaviour in transverse tension of commingled PP/glass fibre yarn composites with different interfacial qualities, and also to investigate the influence of a silane based glass sizing and of a PP-g-MAH matrix coupling on the water absorption level and on the desorption rate of these materials. It was observed that the aminosilane fibre sizing protected these materials very well against water, and that the fibre sizing resulted in a diminution of the amount of absorbed water. It is shown that the better the adhesion, the longer the water stayed inside the composite material. This appears to be the counterpart of the protecting role against moisture of a strong interface. The interfacial interactions act as barriers during absorption and also during desorption, leading to water molecule entrapment. The persistence of water trapped at the interfaces in the case of sized glass fibres composites, leads to the recommendation to investigate the long term effects on longitudinal tension properties, since the effects of zero-stress ageing are known to reduce fibre strength, it is stated. 29 refs.

Title: AMIDE-CONTAINING BISMALEIMIDE RESINS AND THEIR COPPER FOIL COMPOSITE MATERIALS
Page Range: p.37-52
Author(s): Meng-Shun Huang; Ming-Chien Yang; Shen Chou
File size: 425K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 1

Abstract
Amide-containing bismaleimide (ACBI) resins were prepared using four monomeric reactants: 3,4'-oxydialine, trimellitic anhydride, maleic anhydride, and 4-aminobenzoic acid. The chemical structures were characterised using elemental analysis and FTIR. The peel strength, dielectric constant, dissipation factor, heat resistance, and chemical resistance were studied. Experimental results show that the optimal hot-press conditions for ACBI/copper foil laminates was 320 degrees C and 4.9 MPa. ACBI laminates treated with 0.2% NZ97 coupling agent were shown to have the highest peel strength of 2.097 kN/m. After 24 hours at 300 degrees C, the peel strength was 1.568 kN/m, the 1 MHz dielectric constant of ACBI was 3.48, and the dissipation factor was 0.0082. Following a hot/wet treatment for 72 hours, ACBI laminates maintained 76% of their original peel strength. After treating in 10% sulphuric acid solution at 60 degrees C for 30 minutes, ACBI laminates were shown to have maintained 88% of their original peel strength. 16 refs.

Title: PREPARATION AND PROPERTIES OF SEMI-TRANSPARENT EPDM/MONTMORILLONITE NANOCOMPOSITES
Page Range: p.53-60
Author(s): Hua Zheng; Yong Zhang; Zonglin Peng; Yinxi Zhang
File size: 142K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 1

Abstract
EPDM/organic montmorillonite (OMMT) nanocomposites were prepared via a melt-mixing process in an internal mixer. The nanoscale dispersion of OMMT in the EPDM matrix was verified by X-ray diffraction and transmission electron microscopy, relating to an exfoliated morphology. The effects of OMMT on the mechanical properties, curing behaviour, optical properties and thermal properties of the EPDM/OMMT nanocomposites were studied. Experimental results indicated that the OMMT provided good reinforcement to the EPDM vulcanisates. Tensile strength and tear strength of the nanocomposites significantly increased with increased filler content. The nanocomposite was cured by 2,5-dimethyl-2,5-bis (tert-butyl peroxy) hexane, and was semi-transparent, the OMMT content having little influence on curing behaviour. Increases in glass transition temperature and thermal decomposition temperature were observed, which are claimed to be related to the nanoscale dispersion of the OMMT and the strong interaction between the matrix and filler. In addition, the permeability of oxygen for the nanocomposite is reported to be markedly reduced. 25 refs.

Title: MORPHOLOGY, CRYSTALLINE STRUCTURE AND ISOTHERMAL CRYSTALLIZATION KINETICS OF POLYBUTYLENE TEREPHTHALATE/MONTMORILLONITE NANOCOMPOSITES
Page Range: p.61-71
Author(s): Defeng Wu; Chixing Zhou; Xie Fan; Dalian Mao; Zhang Bian
File size: 283K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 1

Abstract
PBTP/montmorillonite (MMT) nanocomposites were prepared by the melt intercalation method, and their microstructure was characterised by wide angle X-ray diffraction and transmission electron microscopy. The XRD results showed that the crystalline plane was smaller than that of unreinforced PBTP, indicating that the crystallite size of PBTP in the nanocomposites could be diminished by the addition of clay. The isothermal crystallisation kinetics of PBTP and PBTP/MMT nanocomposites was investigated by DSC. During isothermal crystallisation the development of crystallinity with time was analysed using the Avrami equation. Results indicated that the addition of very small amounts of clay dramatically increased the rate of crystallisation and high clay concentrations reduced the rate of crystallisation at the low crystallisation temperatures. Activation energies of crystallisation for PBTP and its nanocomposites were calculated by the Arrhenius relationship, and the results showed that the nanocomposites with a low clay content had the lower activation energy values than PBTP, while high amounts of clay, increased the activation energy of PBTP. 25 refs.

Title: FATIGUE BEHAVIOUR OF MULTILAYER BRAIDED FABRIC REINFORCED LAMINATES
Page Range: p.73-81
Author(s): Zheng-Ming Huang; Teng X C; Ramakrishna S
File size: 290K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 1

Abstract
This paper investigates the fatigue behaviour of laminated composites made from an epoxy matrix and four layers of flat regular braided carbon fibre fabrics of different braiding angles. Static tensile and tension-tension fatigue tests were conducted for those laminates and detailed fatigue data are reported. Failure mechanisms for the tested laminates are also characterised. When a laminate was fabricated using multilayers of braided fabric laminas of the same braiding angle, no delamination was found. Thus, a braided fabric laminate would be more delamination resistant than an angle plied laminate with the same angle. However, it was found that when the laminate was made of combined laminas with different braiding angles, significant delamination can be found because of the existence of sufficiently high shear stresses between the combined layers. This is claimed to suggest that in order to diminish delamination, a stacking of braided fabric laminae of different braiding angles should be avoided. 16 refs.

Title: THERMAL CONDUCTIVITY OF NEEDLE PUNCHED PREFORMS MADE OF CARBON AND OXIPAN FIBRES
Page Range: p.83-92
Author(s): Jae Yeol Lee; Tae Jin Kang
File size: 185K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 1

Abstract
The thermal conductivity of preforms made by a needle punching technique was measured using a tailor-made apparatus. Measurements were carried out in the absence of the matrix resin to find the thermal conductivity of the preforms themselves. The preforms were made with a variety of material compositions and textile structures, and various needle punching densities. Preforms made of woven fabric are reported to have shown higher thermal conductivity than those of felt fabric. It was also shown that needle punching density had a strong influence on the thermal conductivity. An increase in the needle punching density decreased the thermal conductivity along the in-plane direction, and increased it along through-the-thickness direction. An analytical model for thermal conduction in both directions was devised, and the results were seen to be consistent with those achieved experimentally. The thermal conductivity of the rearranged fibres in the punching hole was estimated by parametric studies. 20 refs.

Title: INFLUENCE OF ELECTRON BEAM IRRADIATION AND STEP-CROSSLINKING PROCESS ON SOLVENT PENETRATION AND THERMAL PROPERTIES OF NATURAL RUBBER VULCANIZATES
Page Range: p.93-103
Author(s): Madani M; Badawy M M
File size: 143K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 1

Abstract
The influence of electron beam irradiation and step-cross-linking on the properties of high abrasion furnace carbon black loaded natural rubber vulcanisates is reported. Results of the tests concluded that the polymer-filler interaction for samples vulcanised by a one-step crosslinking process was high compared with that for those vulcanised via a two-step crosslinking process. The study also examined the effect on solvent (methyl ethyl ketone) penetration into the loaded vulcanisate. The maximum amount of solvent uptake decreased with the carbon black content and also with the irradiation dose, while the thermal conductivity increased because of an increase in crosslink density. The model proposed by Agari et al to calculate the effective thermal conductivity of the composite was tested as a function of electron beam irradiation dose and the step-crosslinking process. 41 refs.

Title: GRAFT COPOLYMERS OF POLY(METHYL METHACRYLATE) ON CELLULOSE AND THEIR USE AS SUPPORTS IN METAL ION SORPTION
Page Range: p.105-116
Author(s): Chauhan G S; Kumar S; Verma M; Sharma R
File size: 139K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 1

Abstract
In order to develop new polymeric materials for environmental technologies based on cellulose, methyl methacrylate was graft copolymerised using benzoyl peroxide as free radical initiator. The cellulose was extracted from pine needles. Reaction conditions for optimum grafting were evaluated. These included concentrations of monomer and initiator, reaction time and temperature, and the nature, amount and composition of the solvent system. Graft copolymers were characterised by FTIR, elemental analysis and swelling behaviour in water and dimethyl formamide. Attempts were made to evaluate the effect of comonomer concentration on the grafting behaviour of methyl methacrylate and on the structure of the copolymers. Candidate copolymers were used as supports for the sorption of metal ions, and results were compared with those obtained using native cellulose, cellulose phosphate and oxycellulose. 22 refs.

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