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Title: MECHANICAL PROPERTIES OF KEVLAR-49 FIBRE REINFORCED THERMOPLASTIC COMPOSITES
Page Range: p.411-424
Author(s): Herbert Yeung K K; Rao K P
File size: 705K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 20
Issue No: No.5

Abstract
Conventional materials made of glass and carbon fibres in thermoset resins are very frequently employed. Recently, thermoplastic matrix composites are being developed to improve the toughness and damage tolerance of composite laminates. The ductility of thermoplastic resins implies a more pronounced plasticity in service. Kevlar fibre has a tensile strength comparable with that of carbon fibre, a modulus between those of glass and carbon fibres and a lower density than both. Kevlar-49 reinforced composites are increasingly demanded in a variety of commercial applications but their understanding is relatively new when compared to traditional fibres. Simple micromechanics based models such as the rule of mixtures, inverse rule of mixtures (ROM), Halpin-Tsai and Xu-Reifsnider models are employed to predict the mechanical properties of Kevlar-49 fibre composites formulations. In this study, the mechanical properties including tensile, compressive and flexural strength and modulus of Kevlar-49 thermoplastic based composites were experimentally obtained and compared with the theoretical predictions. A systematic costing analysis of respective thermoplastic composites has been made for the provision of composite selection guidelines for designers. 32 Refs.

Title: COMPRESSION AND RECOVERY BEHAVIOUR OF POLYAMIDE-6 BASED FOAMS
Page Range: p.425-438
Author(s): Izzard V G; Hadavinia H; Morris V J; Foot P J S; Wilson L; Hewson K
File size: 672K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 20
Issue No: No.5

Abstract
This paper presents experimentally determined compression sets and compression behaviour of two closed-cell, crosslinked foam materials; ZOTEK N B50 (Nylon 6) and ZOTEK N A30 (nylon/polyolefin alloy). This work forms the basis of future investigations into the post-impact behaviour of these foams. Compression set performance was measured at 25.0, 37.5 and 50.0% strain at nine temperatures ranging from -5 to 90 degrees C. Compression tests at constant strain rates were conducted at four temperatures between 23 to 90 degrees C. Finally compression tests at 23 degrees C were repeated at four strain rates between 0.3 and 550 hr-1 to determine strain rate dependency. The Nagy and Williams-Landel-Ferry scaling factor for strain rate and temperature were applied to the experimental results and equations were derived which allowed the performance of the two polyamide based foams to be interpolated over the strain rate and temperature range of study. The required material properties of interest of the base polymers have been assessed and are presented and discussed in relation to the performance of the foam materials. 30 Refs.

Title: MECHANICAL PROPERTIES OF RECYCLED POLYPROPYLENE/SBR RUBBER CRUMBS BLENDS REINFORCED BY BIRCH WOOD FLOUR
Page Range: p.439-444
Author(s): Adel Ramezani Kakroodi; Leduc S; Gonzalez-Nunez R; Rodrigue D
File size: 331K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 20
Issue No: No.5

Abstract
In this work, recycled polypropylene (PP) and regenerated styrene butadiene rubber (SBR) from used tyres rubber crumbs were combined to produce polymeric blends. The compounds were prepared via twin-screw extrusion to measure their mechanical behaviour for different SBR compositions (0 to 40%). Also, the addition of birch flour (0 to 40%) and coupling agent (0 to 5 phr) content were studied. The results showed that tensile strength and modulus of the blends were substantially improved after incorporation of wood flour. The torsion modulus also increased with birch content. However, the tensile strain at break of PP/birch wood composites decreased with both wood and coupling agent contents, showing a decrease in ductility of the composites. Adding the elastomer phase did not improve the properties. The results showed that adding a coupling agent was found to be effective in improving the wood flour-PP interface, while less improvement was observed for the rubber-PP surface adhesion. The tensile strength of PP/birch composites improved by more than 60%, while the torsion and tensile moduli of the composites improved by only 10% in some cases.19 refs.

Title: DEPENDENCE OF AMINO-FUNCTIONALIZATION ON INTERFACIAL ADHESION STRENGTH IN EPOXY/AL LAMINATED COMPOSITES
Page Range: p.445-452
Author(s): Qiwen Guo; Qingyu Peng; Yibin Li; Lei Mei
File size: 444K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 20
Issue No: No.5

Abstract
In epoxy/Al laminated composites, the interface between polymers and metals plays the role of load transfer from epoxy to Al. However, the interfacial bonding between epoxy and aluminium tends to be weak. In this paper, in order to improve the interfacial strength the dendrimer layer---poly (amido amine) (PAMAM) was used to realize the amino functionalisation of the interface of epoxy/Al laminated composites. The amino functionalisation was tuned by controlling the hydroxyl group concentration through different Al surface treatments. The results show the interfacial adhesion strength between aluminium and epoxy was highly dependent of amino group content. The adhesion strength of epoxy/Al interface is increased by 50% after PAMAM layer was introduced into the NaOH-treated interface between epoxy and Al surface. 21 Refs.

Title: APPLICATION OF MODIFIED CALCIUM SULFATE WHISKER IN METHYL VINYL SILICONE RUBBER COMPOSITES
Page Range: p.453-462
Author(s): Wang Jincheng; Tang Lijuan; Wu Ding; Guo Xi; Hao Wenli
File size: 602K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 20
Issue No: No.5

Abstract
Novel methyl vinyl silicone rubber (MVQ)/calcium sulphate whisker (CSW) composites had been prepared. Two types of modification agents, hydrogen silicone oil and silane coupling agent, were used in the preparation of modified calcium sulphate whiskers (MCSW). The morphology and properties of MCSW were analyzed by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Then, the two types of MCSW were applied in the preparation of MVQ composites. Properties such as cure characteristics, tensile strength, elongation at break, permanent distortion and thermal stability were analysed and compared. Results showed that addition of MCSW could improve the tensile and thermal properties of the silicone rubber composites. A combination of SEM studies was used to characterize the structure and reinforcing mechanism of MCSW. 21 Refs.

Title: PREPARATION AND CHARACTERIZATION OF NANOCOMPOSITES BASED ON POLY(EPSILON-CAPROLACTONE) AND THE SURFACE GRAFTED NANOHYDROXYAPATITE WITH THE COMB-SHAPED POLY(EPSILON-CAPROLACTONE) BRUSHES
Page Range: p.463-470
Author(s): Guoxin Fu; Liang Zeng; Jianwei Jiang; Zhixiang Xia; Bo Jing; Xuefei Zhang
File size: 414K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 20
Issue No: No.5

Abstract
Surface modified hydroxyapatite/poly(/-caprolactone) composites with comb-shaped poly (r-caprolactone) (PCL) brushes grafted hydroxyapatite (n-HAP) were synthesised by a combination of atom transfer radical polymerisation (ATRP) and ring-opening polymerisation (ROP).,. Compared to the corresponding unmodified n-HAP/PCL composites, at modified n-HAP contents of 15 wt.% and 20% with a grafting ratio of 26.32%, the composites showed a maximum tensile modulus and elongation at break, flexural modulus and bending strength, respectively. This suggested that the comb-shaped PCL brushes at the interface are of advantage to the improvement of interfacial adhesion between the n-HAP and PCL polymer matrix by chain interdiffusion and entanglement with the PCL matrix. Furthermore, the observation should be attributed to the modified n-HAP particles, which were uniformly distributed in the polymer matrix and acted as heterogeneous nucleating agents during the crystallisation of the PCL matrix. 29 Refs.

Title: PREPARATION, CHARACTERIZATION AND STUDY OF THE MORPHOLOGICAL, MECHANICAL AND THERMAL PROPERTIES OF EPOXY/URETHANE INTERPENETRATING POLYMER NETWORKS NANOCOMPOSITES
Page Range: p.471-478
Author(s): Mehdi Ghafghazi; Masoud Esfandeh; Jalil Morshedian; Shiva Ghafghazi
File size: 412K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 20
Issue No: No.5

Abstract
In this study epoxy/urethane (EP/PU) graft interpenetrating polymer networks (g-IPNs) nanocomposites were prepared by a simultaneous polymerisation method and the effects of organophilic montmorillonite (Cloisite 30B) content on the mechanical, morphological and thermal properties of the nanocomposites were investigated. Cloisite 30B was dispersed in epoxy resin via a sonication method, after which g-IPN nanocomposites were prepared by thorough mixing of a synthesised isocyanate-terminated urethane pre-polymer with this epoxy resin (EP/PU weight ratio=75/25) followed by simultaneous curing of the resins. Polytetramethylene ether glycol (PTMEG) with molecular weight (Mw) of 3000 g/mol was used to prepare urethane prepolymers. Curing reactions were followed by Fourier Transform Infrared spectroscopy (FT-IR). Wide Angle X-ray diffraction (WAXD) was used to investigate the dispersion of Cloisite 30B in g-IPN nanocomposite specimens. Based on these results, an exfoliated morphology has been suggested for nano IPN specimens containing 1 and 3 wt.% of Cloisite 30B and an intercalated morphology for that with 5 wt.% of Cloisite 30B. Dynamic Mechanical Thermal Analysis (DMTA) was used to determine the glass transition temperature (Tg) of the IPNs. The maximum Tg was observed for the nanocomposite with 3 wt.% of Cloisite 30B. The storage modulus (E') of nanocomposites increased with increasing clay content. Thermogravimetric Analysis (TGA), tensile measurements and Scanning Electron Microscopy (SEM) were used to study the thermal, mechanical and morphological properties of the prepared specimens. The maximum tensile properties were obtained at 3 wt.% of Cloisite 30B. Furthermore, with increasing clay content, the onset of the thermal degradation temperature was delayed. 25 Refs.

Title: NEW PHOTOSENSITIVE POLYAMIDE/ORGANOCLAY NANOCOMPOSITE PREPARED BY A SOLUTION DISPERSION TECHNIQUE
Page Range: p.479-486
Author(s): Meisam Shabanian; Khalil Faghihi
File size: 368K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 20
Issue No: No.5

Abstract
Photosensitive polyamide/layered silicate nanocomposites (PAN) were prepared via a solution polymerisation process from polyamide 3 containing chalcone moieties and organo-MMT in a solution of N,N-dimethylacetamide. Incorporation of small amounts of an organoclay can reduce the coefficient of thermal expansion (CTE) of photosensitive polymer formulations (photoresists). The organoclay was examined for its dispersion behaviour in the polyamide matrix. Polyamide chains were synthesised from 4,4'-diaminochalcone 2 and terephthaloyl chloride (TPC) in dimethylacetamide. These amide chains were selectively end-capped with carbonyl chloride end groups to interact chemically with modified montmorillonite clay. The resulting composite films containing 5-15 wt.% of organoclay were characterized by SEM, XRD, TGA, DSC and water absorption measurements. The distribution of organoclay and nanostructure in the composites was investigated by XRD and SEM analyses. The photosensitive properties of the polyamide 6 in the DMF solution were studied by UV spectrophotometry. The nanocomposites exhibited increases in their glass transition temperatures relative to pristine polyamide, implying interfacial interactions between the two phases. The percentage water absorptions of the polymers were found to be much reduced upon the addition of modified layered silicates indicating decreased permeability. 20 Refs.

Title: FT-IR STUDIES ON THE CYCLIZATION REACTION OF ACRYLIC FIBRES
Page Range: p.487-492
Author(s): Reza Eslami Farsani
File size: 274K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 20
Issue No: No.5

Abstract
In this paper, chemical structure of three different acrylic fibres containing itaconic acid (IA), sodium methallyl sulphonate (SMS) and sodium 2-methyl-2-acrylamidopropane sulphonate (SAMPS) comonomers were studied by Fourier transform infrared (FT-IR) spectroscopy. This study was conducted in order to find the effects of precursor type acrylic fibres on the chemical interaction during the stabilisation and on the properties of fabricated carbon fibres. The results of FT-IR show that the peaks related to CTN bonds in acrylic fibres containing IA comonomer were completely removed during stabilisation, while the peaks in SAMPS and SMS were just reduced. Also, the peak related to CH2 bond for acrylic fibres containing IA comonomer was reduced sharply in comparison with the other two fibres. These changes show that cyclisation of nitrile groups and stabilisation reactions in acrylic fibres having IA comonomer were completed. These reactions increase the tensile strength of carbon fibres produced from this material in comparison with other carbon fibres produced from acrylic fibres containing SAMPS and SMS. 23 Refs.

Title: THE FLEXURAL, IMPACT AND THERMAL PROPERTIES OF UNTREATED SHORT SUGAR PALM FIBRE REINFORCED HIGH IMPACT POLYSTYRENE (HIPS) COMPOSITES
Page Range: p.493-502
Author(s): Bachtiar D; Sapuan S M; Khalina A; Zainudin E S; Dahlan K Z M
File size: 649K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 20
Issue No: No.5

Abstract
This study investigated the mechanical and thermal performance of short sugar palm (Arenga pinnata) fibre reinforced high impact polystyrene composites. Fibre sizes of 30-50 mesh and five different fibre loadings from 10 to 50% by weight have been used. The melt mixing method and hot compression moulding were used as the fabrication techniques for the composites. The flexural behaviour, impact testing, dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and the moisture absorption of short SPF-HIPS composites reinforced with varying fibre loadings were studied. The results showed that increasing the loading of short SPF in the HIPS matrix improved the flexural moduli of the composites. Lower impact strength resulted when the fibre loading was increased, and the moisture content increased significantly. The DMA test results showed increases in the storage modulus and thermal stability for the SPF-HIPS composites. Finally, the TGA test showed degradation behaviour of the composites when they were exposed to a high temperature environment. With some advantage embedding these fibres can be an alternative choice of natural fibre for reinforcing thermoplastics. 26 Refs.

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