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Polymers and Polymer Composites

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Title: GLASS FIBRES RECOVERED BY MICROWAVE PYROLYSIS AS A REINFORCEMENT FOR POLYPROPYLENE
Page Range: p.333-340
Author(s): Akesson D; Ramesh Krishnamoorthi; Zenon Foltynowicz; Jonas Christeen; Adib Kalantar; Skrifvars M
File size: 408K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 21
Issue No: No.6

Abstract
Glass fibre composites were recycled by microwave pyrolysis. The glass fibres recovered were evaluated as a reinforcement agent for polypropylene (PP). Samples were prepared with a micro-compounder and the resulting compounds were evaluated with tensile testing, flexural testing, Charpy impact testing and scanning electron microscopy (SEM). The adhesion between fibre and glass was relatively poor, and an attempt was made to improve it. Various coupling agents were evaluated, in addition to the use of maleic anhydride-grafted PP (MAPP). Tests showed that MA-PP had a relatively strong effect on the mechanical properties. 29 Refs.

Title: CURING METHODS FOR ADVANCED POLYMER COMPOSITES - A REVIEW
Page Range: p.341-348
Author(s): Dilmurat Abliz; Yugang Duan; Leif Steuernagel; Lei Xie; Dichen Li; Ziegmann G
File size: 286K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 21
Issue No: No.6

Abstract
Advanced polymer composites have obtained great application interest in a number of demanding aerospace, wind energy, automotive, infrastructure, and consumer applications. Great varieties of advanced polymer composites curing methods investigated to develop low-cost and high-efficient fabrication of advanced polymer composites, which still remains as a great challenge and thorny issue. Especially, the autoclave curing process, which is widely used for curing of high performance advanced polymer composites, is labour- and capital-intensive, with costs increasing exponentially with part size and limiting increased use of advanced polymer composites. Researchers and industries have long desired to explore and develop low-cost and high-efficient curing methods for fabrication of advanced polymer composites and investigated different radiation and thermal curing alternatives. In this paper, current development status of the radiation curing (gamma ray, x-ray, ultraviolet, accelerated electron beams) and thermal curing (radiation heating (infrared, laser and microwave), convection and conduction heating (hot gas, flame, oven and hot shoe), induction heating, ultrasonic heating, resistance heating and thermal additives (magnetic particles, NIR absorbent particles) based heating methods applied for the curing of advanced polymer composites are reviewed. The curing mechanism and current application status of the different curing processes for fabrication of advanced polymer composites is discussed, and main advantages and disadvantages of these methods are comparatively analysed and evaluated according to the material, cost, feasibility and power criteria for successful curing application of advanced polymer composites. 72 Refs.

Title: ELECTROSPUN ULTRATHIN POLY(VINYL ALCOHOL) FIBRE ASSEMBLIES MODIFIED BY MEANS OF POLYCARBOXYLIC ACID / SODIUM HYPOPHOSPHITE
Page Range: p.349-356
Author(s): Schramm C; Rinderer B; Tessadri R
File size: 398K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 21
Issue No: No.6

Abstract
A viscous solution consisting of poly(vinyl alcohol) (PVA), butane-1,2,3,4-tetracarboxylic acid (BTCA) and sodium hypophosphite monohydrate (SHP) has been prepared and subjected to an electrospinning process in an attempt to produce BTCA-crosslinked ultrathin PVA fibre mats. At elevated temperatures the carboxyl groups of BTCA react with the hydroxyl groups of PVA via a five-membered cyclic anhydride thus forming ester linkages. The measurement of the fibre diameters of the electrospun fibres created at various high voltages (10, 15, and 20 kV) revealed that the diameters of the fibres were in the range of 0.98 - 1.20 (mu)m. Single layer and double layer fibre assemblies were prepared and thermally treated at 180 deg C. The as-prepared ultrathin PVA fibre assemblies were analysed by means of scanning electron microscopy (SEM), indicating that the morphology of the fibres had been changed. Fourier transform infrared/attenuated total reflection spectroscopy (FT-IR/ATR), X-ray powder diffraction (XRPD) and physical properties, such as water vapour absorption (WVA), water vapour transmission (WVT) and tensile strength were evaluated. The incorporation of BTCA resulted in an increase of WVA and a decrease of WVT. The tensile strengths of the cured PVA mats were remarkably decreased, when BTCA/SHP had been added. 39 Refs.

Title: THERMAL ANALYSIS OF HIGHLY FILLED COMPOSITES OF POLYSTYRENE WITH LIGNIN
Page Range: p.357-366
Author(s): Reza Barzegari M; Ayse Alemdar; Yaolin Zhang; Rodrigue D
File size: 418K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 21
Issue No: No.6

Abstract
This paper focuses on the thermal properties of polystyrene/lignin composites over a wide range of lignin content. Blending with and without a compatibiliser (styrene/ethylene/butylene copolymer) was performed in an internal batch mixer to prepare samples between 0 and 80%wt of lignin. From the compounds, an extensive thermal study was performed, including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). TGA results indicated that the thermal stability of polystyrene increases with increasing lignin content. DMTA analysis showed higher storage modulus and lower loss factor with increasing lignin content for the range of temperature studied (30-150 deg C). DSC results showed that the lignin/PS composites have a single Tg which is close to that of polystyrene. The addition of a compatibiliser up to 2%wt was found to improve the storage modulus of lignin/PS composite, especially at low temperature. Finally, scanning electron microscopy micrographs were used to show the state of interfacial adhesion or compatibility between lignin particles and the polystyrene matrix. 29 Refs.

Title: GLASS TRANSITION BEHAVIOUR OF PMMA/PVA INCOMPATIBLE BLEND
Page Range: p.367-376
Author(s): Yoshinobu Nakamura; Eiji Kariya; Tomoyoshi Fukuda; Syuji Fujii; Kazuko Fujiwara; Shigeki Hikasa
File size: 382K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 21
Issue No: No.6

Abstract
Dynamic viscoelastic properties and morphology of poly(methyl methacrylate) (PMMA)/poly(vinyl alcohol) (PVA) blend prepared by melt kneading was investigated. These solubility parameter values differ greatly. Two kinds of PVA with saponification degrees of 88 and 98 mol.% were used. Micrometre-order domains were observed by scanning electron microscopy for 88 mol.% PVA, whereas no clear domain was observed for 98 mol.%. Both the blends were incompatible systems because two loss modulus peaks based on PMMA and PVA were observed by dynamic mechanical analysis. The loss modulus peak based on the PMMA-rich phase was higher than that of pure PMMA; the increase of the corresponding glass transition temperature (Tg) caused by blending was more remarkable for 98 mol.% PVA than 88 mol.%. It was thought that the intermolecular interaction of OH group in PVA and carbonyl group in PMMA caused the increase in Tg, but no clear evidence of the interaction for the blend was observed by a Fourier transform infrared spectroscopic analysis. The poly(vinyl acetate)/PMMA blend was incompatible. The unsaponificated vinyl acetate unit in PVA decreased the interaction between PMMA and PVA. This is the reason why the effect of Tg rising was lower for 88 mol.% PVA than for 98 mol.%. 13 Refs.

Title: ANALYSIS OF MARCHING-MODULUS RUBBER RHEOGRAMS
Page Range: p.377-386
Author(s): Farid A S; Arunashanthi K D
File size: 484K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 21
Issue No: No.6

Abstract
Rheometry is widely used throughout the rubber industry to characterise the cure behaviour of rubber mixes. Industrial rheometers produce continuous traces or rheograms in which torque is plotted as a function of time as a rubber progressively cures. Rheograms in which a distinct maximum or steady-state value is obtained within a reasonable time present few problems when the main objective is to determine optimum vulcanisation times. Nevertheless, some rubber mixes display cure profiles that do not exhibit steady-state values within acceptable time scales; taking extremely long periods of time to do so. Running rheometers over prolonged periods in order to attain flat or steady state cures is neither productive nor economical. In such situations, it is desirable to develop a methodology whereby steady-state values can be estimated from short running times. Assuming that cure advances by way of first-order kinetics a graphical technique is introduced enabling the steady-state torque value to be estimated from short running times. The steady-state torque value obtained from the graphical procedure was compared with experimental values; poor agreement was found being within about 11%. Notwithstanding the poor agreement between the steady-state torque value observed experimentally and that predicted by the graphical method we nevertheless continue to recommend the use of the graphical technique. Our justification for the use of the graphical method is that the procedure provides reliable rate constants for the incipient stages of vulcanisation without having to determine full extents of cure. The rate constant determined by the graphical procedure was in good agreement with typical values reported in the literature7 thus affording credibility to our graphical methodology. As further confirmation as to the reliability of our technique, an analytical method introduced by Rigby2 was employed to verify the authenticity of our results. Comparison of our results with those ascertained from the analytical method showed reasonable agreement. In order to account for the significantly large difference between the graphically-estimated and experimental steady-state torque value, the ideal and simplistic assumption that curing proceeds by first order kinetics throughout the entire curing period was abandoned. Instead, it was assumed that the crosslinking process comprises two concomitant first-order curing reactions; notably normal and slow crosslinking reactions. The kinetic expression describing the two simultaneous vulcanisation reactions in terms of rheometry parameters is: Tt-Ta = (Tc Ta)(1-e-kc(t-ti))+(Tsc-Ta)(1-e-ksc(t-ti))where Tt is the torque at time t; Ta is the minimum torque; ti is the induction time; T(Yen),c and T(Yen),sc are the steady state torque values for the normal and slow crosslinking processes respectively; and, kc and ksc represent the first-order rate constants for the normal and slow crosslinking processes respectively. Excellent agreement was found between the experimental steady-state torque value and that predicted by the composite kinetic expression. 7 Refs.

Title: APPLICATION OF TAGUCHI METHOD IN OPTIMIZING FABRICATION OF COMPOSITE PANELS FOR INTERIOR DIVIDING WALLS
Page Range: p.387-394
Author(s): Velosa J; Rana S; Santos T; Fangueiro R; Ramos L
File size: 307K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 21
Issue No: No.6

Abstract
In order to save material and energy, an increased growth can be noticed in recent times in the use of low-cost and light-weight solutions for the interior dividing walls of buildings. In this context, the main aim of the present research work was to develop light-weight composite panels based on non-woven fabrics for this application as an alternative to more commonly used materials and to optimize the manufacturing process parameters in order to maximize their mechanical performance. Thermo-bonded nonwoven geo-textiles made from polyester (70%) and polypropylene (30%) fibres were consolidated using compression moulding technique, varying the various structural and process parameters, such as number of layers, compression time, temperature and pressure. Taguchi method was used to design the experiments, as well as to understand the influence of various parameters on tensile and flexural strengths of developed composite panels and to optimize them in order to maximize these properties. According to the analysis, a consolidation temperature of 210 deg C, pressure of 30 bars, compression time of 35 minutes and 30 layers are required to achieve the maximum values of tensile and flexural strength with minimum variability. 21 Refs.

Title: STUDY ON MECHANICAL PROPERTIES AND WATER ABSORPTION BEHAVIOUR OF WASTEPAPER FIBRE/RECYCLED POLYPROPYLENE COMPOSITES
Page Range: p.395-402
Author(s): Zhang Xiaolin; Bo Xiangfeng; Wang Rumin
File size: 389K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 21
Issue No: No.6

Abstract
There has been growing interest in the use of waste materials as an alternative source for the conventional woodplastic composites (WPC) in the global market. This paper evaluates the feasibility of two different kinds of wastepaper fibre as reinforcing materials used for WPC. For this purpose, the fibre morphology of old newspaper fibre (ONPF) and old magazine paper fibre (OMGF) was investigated by fibre morphology analyser, respectively. Wastepaper fibres, recycled polypropylene (rPP), and 2%MAPP were compounded by double-roller mixer and test specimens were prepared by hot press moulding. The tensile, flexural, and water absorption properties of ONPF and OMGF reinforced rPP composites as a function of fibre content were studied. The results showed that the highest mechanical properties of ONP and OMG fibre reinforced composites could be reached with 30 wt.% fibre contents. The mechanical properties of the composites made from ONP fibres were better than those made from OMG fibres. However the addition of wastepaper fibres resulted in a decrease in elongation at break. Both the fibre loading and the fibre morphological characteristics had an effect on the water uptake behaviour. But the effect of fibre size on the water uptake was minimal compared to that of the fibre content. The water uptake of wastepaper fibre/rPP composites may actually be slowed down rather than delayed. Scanning electron microscopy (SEM) of the fracture surface of a tensile specimen with 30 wt.% wastepaper fibre loading showed good fibre dispersion in the matrix and a good compatibility between wastepaper fibre and rPP matrix. The results suggested that both the ONP fibres and the OMG fibres could be used as potential sources and reinforcing agent for composites, but the reinforcement effect of ONPF was better than that of OMGF. 22 Refs.

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