Back SearchTitle: INJECTION MOULDING OF LONG-GLASS-FIBRE-REINFORCED POLY(ETHYLENE TEREPHTHALATE): INFLUENCE OF PROCESSING CONDITIONS ON FLEXURAL AND IMPACT STRENGTHS
Page Range: p.577-588
Author(s): Cilleruelo L; Lafranche E; Krawczak P; Pardo P; Lucas P
File size: 328K
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Issue Year: ppc
Volume: 16
Issue No: No.9
Abstract
An attempt was made to identify the main parameters that influenced the mechanical properties of long glass fibre-reinforced PETP parts in order to optimise the potential of these composites. A Taguchi design of experiments was used for this purpose. The shape of the injection-moulded specimen was representative of the complexity of industrial parts (presence of sharp frontal and tangential steps). The mechanical properties (bending and Charpy impact tests) were measured at different locations in the part in order to highlight anisotropy. Variance analysis showed that holding pressure, injection speed and mould temperature were the most effective processing parameters. It was also shown that the optimised parameter sets that led to the highest flexural strength on the one hand and the highest impact strength on the other hand were different, the polymer melt and mould temperatures being opposite. Finally, microstructure analysis showed a fibre content gradient along the flow axis, which was greatly amplified by the presence of geometrical accidents (frontal and tangential steps) including the reorientation of fibres in the flow direction at the end of the parts. 26 refs.
Title: MECHANICAL, MORPHOLOGICAL, AND STRUCTURAL CHARACTERISTICS OF CAROA (NEOGLAZIOVIA VARIEGATA) FIBRES
Page Range: p.589-595
Author(s): D'Almeida J R M; D'Almeida A L F S; De Carvalho L H
File size: 293K
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Issue Year: ppc
Volume: 16
Issue No: No.9
Abstract
The surface morphology, thermal behaviour and tensile mechanical properties of raw caroa (Neoglaziovia variegata) fibres were characterised. Caroa is a native bush in the semi-arid north-eastern region of Brazil, the lignocellulose fibres from which have potential as reinforcement in resin-matrix composites. The influence of fibre washing with flowing tap water on the surface morphology and thermal properties of these fibres was also investigated. The results showed that gummy tissues were attached to the surface of the raw fibres and that washing led to the partial removal of these tissues and to the exposure of the inner fibrillar structure of the fibres. TGA indicated that fibre thermal degradation was characterised by three main degradation stages corresponding, respectively, to water release at low temperatures, followed by decomposition of hemicellulose and of alpha-cellulose. Fibre washing produced an increase in the fibre thermal degradation temperature and in the thermal decomposition rate. These characteristics were associated with the removal of gummy tissues and with a decrease in the compactness of the fibres, respectively. The tensile properties obtained placed caroa as a low-to-medium-strength fibre when compared with other lignocellulosic fibres, but with a strength level similar to that of coir fibres, which are used commercially on a fairly large scale. 25 refs.
Title: STUDY OF THE PROPERTIES OF PLASTICISED POLY(LACTIC ACID) WITH POLY(1,3-BUTYLENE ADIPATE)
Page Range: p.597-604
Author(s): Wang Ning; Zhang Xingxiang; Yu Jiugao; Fang Jianming
File size: 473K
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Issue Year: ppc
Volume: 16
Issue No: No.9
Abstract
Poly(1,3-butylene adipate)(PBA) was used as a novel plasticiser for polylactic acid(PLA) and acetyltributyl citrate(ATBC) was used as the control. FTIR revealed that interaction took place between PLA and plasticiser. With an increasing plasticiser content, storage modulus and Tg decreased, but EB increased. The EB of PBA-plasticised PLA (PBA content 30 wt %) could be above 600%, higher than that of ATBC-plasticised PLA (ATBC content 30 wt %). Moreover, PBA was able to restrain thermally-induced migration of plasticiser in plasticised PLA. It was also found that the migration rate of ATBC was directly proportional to the ATBC content in the blends. The rheology showed that the plasticiser could obviously decrease the shear viscosity and improve the fluidity of the blends. PBA was, therefore, recognised as a novel plasticiser for enhancing the properties of PLA. In particular, as a biodegradable polymer, PBA, when used as a plasticiser in PLA, could enhance migration resistance for its proper molec.wt. Furthermore, the area of application of plasticised PLA was broadened. 18 refs.
Title: PREPARATION, SURFACE MORPHOLOGY, AND THERMAL STABILITY OF POLYAMIDE 6 COMPOSITE NANOFIBRES BY ELECTROSPINNING
Page Range: p.605-610
Author(s): Yibing Cai; Dan Tao; Qufu Wei; Weidong Gao
File size: 371K
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Issue Year: ppc
Volume: 16
Issue No: No.9
Abstract
Polyamide 6(PA6)/organically modified montmorillonite(O-MMT) composite nanofibres were prepared by a facile compounding and electrospinning method. The O-MMT was firstly dispersed in DMF and then compounded with PA6 which was dissolved in formic acid. The composite solution was electrospun to form PA6/O-MMT composite nanofibres. The structures and morphology of the composite nanofibres were characterised by SEM, X-ray photoelectron spectra, atomic force microscopy, X-ray diffraction and TEM. It was found that the O-MMT layers were well exfoliated within the composite nanofibres and were oriented along the fibre direction. The homogeneous and cylindrical composite nanofibres showed decreased fibre diameters owing to the enhanced conductivity of the polymer solution. The results characterised by TGA showed that the loading of O-MMT improved the thermal stability of the composite nanofibres. 25 refs.
Title: COMPRESSIVE STRENGTH OF FRP-CONFINED CONCRETE AT ELEVATED TEMPERATURES
Page Range: p.611-620
Author(s): Al-Salloum Y A
File size: 335K
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Issue Year: ppc
Volume: 16
Issue No: No.9
Abstract
An experimental programme was conducted to investigate the effect of high temperature on the performance of concrete cylinders externally confined with fibre-reinforced polymer(FRP) sheets. For this purpose, 42 small-scale concrete cylinders measuring 100 x 200 mm were cast. Of these 42 specimens, 14 specimens were left unwrapped to be used as baseline or control specimens, 14 specimens were wrapped with one layer of CFRP sheets, and the remaining 14 specimens were wrapped with GRP sheets. These specimens were exposed to room temperature and heating regimes of 100 and 200 deg C for periods of 1, 2 and 3 h. The specimens were tested in compression, and their performance was evaluated after they had been exposed to specific heating regimes. The test results demonstrated that, at a temperature around the Tg of the resin, CFRP- and GRP-wrapped specimens experienced a small loss of strength, resulting from melting of epoxy resin. This damage was more pronounced when the temperature reached 200 deg C. 14 refs.
Title: IN SITU SYNTHESIS OF POLYSTYRENE/SiO"2 HYBRID COMPOSITES VIA A 'GRAFTING THROUGH' STRATEGY BASED ON NITROXIDE-MEDIATED RADICAL POLYMERISATION
Page Range: p.621-626
Author(s): Yunpu Wang; Yongqian Shen; Xiaowei Pei; Wenjuan Zhang; Yuli Wei; Chao Yang
File size: 274K
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Issue Year: ppc
Volume: 16
Issue No: No.9
Abstract
Polymer-grafted nanosilica hybrid composites possessing a hard backbone of nanosilica and a soft shell of brush-like PS were prepared via a 'grafting through' strategy based on nitroxide-mediated radical polymerisation using 2,2,6,6-tetramethylpiperidine-N-oxyl(TEMPO) as the mediator. Two steps were used to graft PS chains to the surface of nanosilica, i.e. anchoring of vinyltrimethoxysilane onto the surface of nanosilica, and then using TEMPO to trap the radicals produced by the reaction of benzoyl peroxide with styrene and the vinyl group in grafted vinyltrimethoxysilane molecules. Finally, well-controlled molec.wt. and narrow MWDs of PS chains were grown from the surface of nanosilica. The prepared PS-g-SiO"2 hybrid particles were extensively characterised by FTIR, X-ray photoelectron spectroscopy, TGA and TEM. 31 refs.
Title: COMPATIBILITY STUDY OF POLYAMIDE 6/POLYVINYLPYRROLIDONE BLEND BY VISCOMETRY, MELTING POINT DEPRESSION AND MORPHOLOGICAL ANALYSIS
Page Range: p.627-633
Author(s): Shi Jie Zhang; Xian Bo Huang; Ming Qiu Zhang; Jian Qing Zhao
File size: 477K
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Issue Year: ppc
Volume: 16
Issue No: No.9
Abstract
Compatibility of blends of polyamide 6(PA6) and polyvinylpyrrolidone(PVP) was investigated by solution viscosity measurement, m.p. depression and morphological analysis. Criteria that represented the interaction of the individual macromolecules were obtained from the solution viscosity measurement of the blends. The results indicated that PA6/PVO blends were partially compatible. From m.p. depression analysis, a negative polymer-polymer interaction parameter was obtained. It provided support for the conclusion from viscometry analysis. Furthermore, typical morphology of partially compatible blend was also revealed by SEM observation of the fractured surfaces of PA6/PVP blends. 34 refs.
Title: EMULSION POLYMERISATION OF St/BuA STABILISED WITH A PEG-CONTAINING GRAFT COPOLYMER
Page Range: p.635-639
Author(s): Linlin Guo; Ge Gao; Xiaoli Liu; Fengqi Liu
File size: 251K
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Issue Year: ppc
Volume: 16
Issue No: No.9
Abstract
An amphiphilic graft copolymer comprising an acrylic backbone and PEO grafts was synthesised and characterised. It was used as surfactant to stabilise the emulsion polymerisation of styrene or butyl acrylate. The effectiveness of different concentrations of this PEO-containing graft copolymer in stabilising the emulsion polymerisation was studied. Finally, stable dispersions of PS microspheres were used as templates, and PS microspheres were coated with Fe"3O"4 by in-situ reaction of Fe^3^+ and Fe^2^+ in the presence of OH^-. No additional treatments were needed in the process. 16 refs.