Back SearchTitle: NUMERICAL PREDICTION OF PERMEABILITY TENSOR FOR THREE DIMENSIONAL CIRCULAR BRAIDED PREFORM BY CONSIDERING INTRA-TOW FLOW
Page Range: p 323-334
Author(s): Song Y S; Chung K; Kang T J; Youn J R
File size: 329K
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Issue Year: ppc
Volume: 13
Issue No: No. 4
Abstract
Resin transfer moulding is characterised by the permeability tensor, which is a measure of the resistance to resin flow through the preform. Complete prediction of the second order permeability tensor for three-dimensional circular braided preforms is critical for an understanding of the resin transfer moulding process. This permeability can be predicted by a consideration of the resin flow through the multi-axial fibre structure. This work calculates the permeability tensor for a 3-D circular braided preform by means of solving a boundary problem of a periodic unit cell. The field flow through the unit cell was obtained by using a 3-D control volume finite element method, and Darcy's law was used to obtain the permeability tensor. Flow analyses were performed for the unit cell by assuming two cases: that the yarns were porous media, and that they were impermeable solids. It was found that the flow within the inter-tow region of the braided preform was negligible if the inter-tow porosity was relatively high, but that flow through the tow, especially in the thickness direction, must be considered when the porosity was low. The permeability of the braided preform was measured by a radial flow experiment and compared with the predicted permeability. 31 refs.
Title: SORPTION OF AROMATIC HYDROCARBONS INTO STYRENE BUTADIENE RUBBER/POLY(ETHYLENE-CO-VINYL ACETATE) BLENDS
Page Range: p.335-357
Author(s): Radhakrishnan C K; Ganesh B; Sujith A; Unnikrishnan G; Thomas S
File size: 701K
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Issue Year: ppc
Volume: 13
Issue No: No. 4
Abstract
The sorption behaviour of SBR/EVA blends with different crosslinking systems is analysed using benzene, toluene and xylene as the penetrants in the temperature range 26-56 degrees C. The effects of various parameters such as blend composition, vulcanising systems, crosslink density, penetrant molecule size and temperature on the sorption parameters were studied. The regular reduction in solvent uptake with increasing EVA content is explained on the basis of the semi-crystalline nature of EVA and its lower free volume. The molecular mass between crosslinks, kinetic rate constant transport coefficients and related thermodynamic parameters have been computed to complement the experimental observations. 46 refs.
Title: FATIGUE LIFE ESTIMATION OF ADHESIVELY BONDED SCARF JOINTS BASED ON A CONTINUUM DAMAGE MECHANICS MODEL
Page Range: p.359-370
Author(s): Imanaka M; Taniguchi M; Hamano T; Kimoto M
File size: 413K
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Issue Year: ppc
Volume: 13
Issue No: No. 4
Abstract
An estimation method of fatigue strength of adhesively bonded joints with various stress triaxialities in the adhesive layer is proposed, which is based on a damage evolution model for high cycle fatigue. The fatigue tests were conducted on adhesively bonded butt and scarf joints for comparison, with various scarf angles bonded by a rubber-modified epoxy adhesive. An equation for estimating the damage evolution in the adhesive layer of the butt and scarf joints was derived from the damage model, in which undefined parameters in the equation were determined by comparing the experimentally derived damage evolution curves of the butt joints with the estimated damage evolution curves. An equation for the estimation of the fatigue strength was derived under the assumption that fatigue failure arises when the damage variable reaches a critical value. Results show that the continuum damage mechanics model used was suitable for estimating the fatigue strength of adhesively bonded joints with different stress triaxialities. 15 refs.
Title: STRUCTURE AND PROPERTIES OF BR NANOCOMPOSITES REINFORCED WITH ORGANOCLAY
Page Range: p.371-384
Author(s): Shaohui Wang; Zonglin Peng; Yong Zhang; Yinxi Zhang
File size: 433K
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Issue Year: ppc
Volume: 13
Issue No: No. 4
Abstract
Butadiene rubber (BR)/organoclay nanocomposites were prepared by direct melt mixing of BR and clay modified with different primary and quaternary ammonium salts. The clay was modified in order to render the hydrophilic silicates more organophilic and thus more compatible with organic polymers. BR/pristine clay composite and BR/organoclay nanocomposites were analysed by X-ray diffraction, SEM, TEM and TGA. The vulcanisation characteristics and mechanical properties of the composites were also investigated. Result showed that the interlayer distance of the organoclays was expanded, which indicated that intercalated BR/organoclay nanocomposites had been prepared. Organoclay accelerated the vulcanisation of BR, which was attributed to the intercalatant used to modify the clay. Tensile strength, elongation at break and tear strength of the BR/organoclay nanocomposites were found to be much higher than those of gum BR vulcanisate and BR/pristine clay composites and the organoclay modified with dimethyl dehydrogenated tallow ammonium chloride was shown to give the best reinforcement effect in BR of all the organoclays. 21 refs.
Title: TOUGHENING MODIFICATION OF POLY(BUTYLENE TEREPHTHALATE)/POLYCARBONATE BLENDS BY POLY(ETHYLENE-CO-OCTENE)
Page Range: p.385-394
Author(s): Huiyu Bai; Yong Zhang; Yinxi Zhang; Xiangfu Zhang; Wen Zhou
File size: 295K
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Issue Year: ppc
Volume: 13
Issue No: No. 4
Abstract
Toughened PBTP/polycarbonate blends were obtained by melt blending with polyethylene co-octene copolymer (POE) varying the POE content up to 10 wt.% in a twin-screw extruder, followed by injection moulding. The influence of POE on the properties of the PBTP/PC blends was investigated using mechanical testing, DMTA, DSC and SEM techniques. Results showed that the addition of POE led to significant increases in the impact strength, elongation at break and Vicat temperature, and a reduction in the tensile strength and flexural properties of the blends. The morphology of the blends was observed using SEM and the average diameter of the dispersed phase was determined by image analysis. The critical inter-particle distance for PBTP/PC blends was determined. 33 refs.
Title: CHARACTERIZATION FORMULA FOR SHEAR STRESS OF POLYMER MELT DYNAMIC EXTRUDING THROUGH CAPILLARY
Page Range: p.395-402
Author(s): Yue Jun Liu; Bai Ping Xu; Pu Shi; Wian Wu Cao; Jin Ping Qu
File size: 133K
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Issue Year: ppc
Volume: 13
Issue No: No. 4
Abstract
The introduction of a vibration force field to strengthen the forming process of a polymer is an important technique known as the dynamic forming technique. During a dynamic forming process, the polymer melt becomes an unstable flow and auxiliary stresses are superimposed on the major shear flow, so the rheological behaviour of the polymer will be decided by the combinatorial stresses. This paper explores the mechanism by which the vibration force field influences the forming process.. A description is given of the sue of a constant velocity type dynamic rheometer, (CVDRC) of capillary designed by the authors to examine the instant entry pressure of capillary, the instant volumetric flow rate and their phase-difference, allowing the distribution of the shear stress within the capillary under vibration force field to be obtained. The research provides a theoretical basis for the investigation of the dynamic forming mechanism of polymers and also for the optimisation of the technological and structural parameters of dynamic forming equipment. LDPE was used as the experimental material and the melt temperature was set at 165 degrees C by regulating the controlling system of heating in CVDRC. 10 refs.
Title: EFFECT OF TETRADECYL METHYL ACRYLATE-MALEIC ANHYDRIDE COPOLYMER ON THE MECHANICAL PROPERTIES OF GLASS MAT REINFORCED POLYPROPYLENE COMPOSITES
Page Range: p.403-413
Author(s): Shanhua Zhou; Zhiyu Xu; Xin Liu; Yan Gao; Qingzhi Dong
File size: 385K
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Issue Year: ppc
Volume: 13
Issue No: No. 4
Abstract
Tetradecyl methylacrylate-maleic anhydride copolymer (TMA-co-MAH) was investigated as a new interfacial modifier in glass mat reinforced PP composites. Its effect on the mechanical properties of the composite were investigated and compared to those of glass mat polypropylenes treated with maleic anhydride grafted PP solutions. The effects of anhydride content, concentration of copolymer and compounding time on the mechanical properties of GMT-PPs were investigated With the optimal monomer ratio, copolymer solution, and compounding time, the impact strength, flexural strength and modulus of GMT-PPs treated with the new interfacial modifier were all significantly improved. 29 refs.
Title: HYDROGEN BONDING EFFECTS ON THE ELECTRICAL PROPERTIES AND PHASE MORPHOLOGY OF POLYANILINE BLENDS
Page Range: p.415-423
Author(s): Pan Wei; Yang Shenglin Y; Li Guang; Jiang Jianming
File size: 259K
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Issue Year: ppc
Volume: 13
Issue No: No. 4
Abstract
In order to improve the processability of polyaniline (PANI), it is doped with dodecylbenzene sulphonic acid, (DBSA). This work examines solution cast blends of PANI-DBSA with either polyacrylonitrile copolymer (PAN) or polystyrene (PS). The study focuses on the interaction between the components, the morphology, and the resulting electrical conductivity of the blends. Results of tests showed that with the same PANI-DBSA content the conductivity of PANI-DBSA/PAN was higher than that of PANI-DBSA/PS. PANI-DBSA was dispersed uniformly in the PAN matrix and its cluster size as rather smaller than in the PS matrix. This was attributed to hydrogen bonding between the carbonyl groups in PAN and the imine groups in PANI, which would lead to better compatibility between PANI-DBSA and PAN. 18 refs.