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Polymers and Polymer Composites

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Title: SILVER ION RELEASE FROM POLYMETHYL METHACRYLATE SILVER NANOCOMPOSITES
Page Range: p.649-56
Author(s): Damm C
File size: 225K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 7

Abstract
Polymers used in medical packaging applications need to be transparent or translucent, and in addition, to have antibacterial properties. A translucent antimicrobial PMMA was prepared which was processable by the usual thermoplastic processing methods. Metallic silver nanoparticles were used as an inorganic antimicrobial filler. The PMMA silver nanocomposites were prepared by the thermal reduction of silver trifluoroacetate. Immersion of the nanocomposites in water led to a release of silver ions. The silver ion release was measured by anodic stripping voltammetry. It was found that since the silver particles situated near the sample surfaces were the main contributors to silver ion release, a coating of PMMA containing nanosilver could be sufficient to create silver releasing composites. 32 refs.

Title: EMI SHIELDING EFFECTIVENESS OF COPPER/EPOXY COMPOSITES
Page Range: p.657-68
Author(s): Wetherhold R C; McManaman J M
File size: 271K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 7

Abstract
The EMI shielding effectiveness of copper reinforced epoxy composites is testing using samples of different shaped, sized and treated specimens. A small amount of nickel powder was including in some specimens to evaluate the effect of magnetic permeability on the shielding effectiveness (SE). Results showed that a smaller fibre diameter resulted in significant SE improvements. SE was also substantially by relatively minor fibre shaping or by fine-scale roughening via chemical treatment. Improvements in SE were also achieved with essentially identical mechanical properties, leading to an effective multifunctional material. The addition of nickel powder led to in an overall improvement in SE as well as a cyclic dependence of SE frequency, which is reported to indicate phase interference at a scale of particle size not previously seen. 26 refs.

Title: IMAGE ANALYSIS OF ELASTOMER MORPHOLOGY IN TOUGHENED THERMOPLASTIC AND THERMOSET RESINS
Page Range: p.669-80
Author(s): Canavate J; Carrasco F; Pages P; Colom X
File size: 293K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 7

Abstract
Image analysis techniques were used to characterised the elastomer morphology of toughened thermoplastic and thermoset resins. The thermoplastic version comprised a polystyrene-based material with styrene-butadiene-styrene dispersed particles. The thermoset material was a polyester toughened with butadiene-acrylonitrile particles. Photomicrographs of the materials with different proportions of elastomer were processed and the images were analysed. Changes in the morphological characteristics were correlated with the fracture toughness and modulus of elasticity. 18 refs.

Title: FT-IR STUDY OF THE MORPHOLOGICAL INTERACTIONS IN PHB/PAZO BLENDS AND THEIR DEPENDENCE ON SOLVENT VARIATION
Page Range: p.681-6
Author(s): Sharma L; Nishida K; Kanaya T
File size: 99K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 7

Abstract
The role played by the solvent in influencing the resultant blend morphology in semi-crystalline polyhydroxybutyrate (PHB) and polycarboxyhydroxyphenylazobenzenesulphonamidoethanediyl, sodium salt (PAZO) blends is demonstrated. The relationship is also established between the blend's FTIR profiles and the morphology. Also investigated is the possible formation of a PHB/PAZO complex. PHB/PAZO blends were prepared in chloroform, acetone and toluene, chosen because of the similarity of their solubility parameter to that of amorphous PHB. By using FTIR, the actual changes occurring within the blends could be demonstrated, and PHB bands could be located, which were associated with any changes in morphology. 14 refs.

Title: SELF-REINFORCING COMPOSITES OF POLYACRYLIC ELASTOMERS AND LIQUID CRYSTALLINE POLYMER: MECHANICAL, THERMAL, AND DYNAMIC MECHANICAL PROPERTIES
Page Range: p.687-95
Author(s): Shivakumar E; Das C K
File size: 216K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 7

Abstract
In order to study the effect of liquid crystalline polymers (LCPs) as reinforcing agents for polyacrylic elastomers (ACM), blends of ACM and a liquid crystalline polymer were prepared using a melt mixing process. The blends were cured with ammonium benzoate and Diak-4,4,4'-methylenebis(cyclohexylamine) carbamate in order to study the curing behaviour of ACM in the presence of LCP. The blends were characterised by use of XRD, TGA, DSC and DMA, and an attempt was made to correlate the structures of the blends seen under scanning electron microscopy with the mechanical properties. Rheometric studies indicated the improved state and rate of cure of the blends with increasing levels of LCP and when Diak-4 was used as the curative. Tear strength and modulus of the ACM/LCP blends increased with increasing LCP content, and they increased at a higher rate in the presence of Diak-4. However, the tensile strength of all the blends reduced dramatically with increasing LCP which was attributed to poor interfacial adhesion between the ACM and LCP phases. The thermal stability of the ACM was affected by the presence of LCP, and the dynamic properties of the blends increased with LCP content. This improvement was reported to be very marked in the presence of Diak-4 curative. 21 refs.

Title: THERMAL STABILITY AND FLAME RETARDANCY OF POLYPROPYLENE WITH PHOSPHORUS, NITROGEN AND SILICON-CONTAINING COMPOUNDS
Page Range: p.697-707
Author(s): Qiang Li; Pingkai Jiang; Zhanpai Su; Ping Wei
File size: 170K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 7

Abstract
Flame retardants containing phosphorus, nitrogen and silicon elements (PSiN) were synthesised and introduced into polypropylene. The thermal stability of PP, PSiN and PP/PSiN were studied by thermogravimetric analysis in nitrogen, air and oxygen atmospheres. The initial decomposition temperature (IDT), maximum-rate degradation temperature (Tmax), integral procedure decomposition temperature (IPDT) and char yield at 800 degrees C in various atmospheres were investigated. Although the IDT of PP was reduced by the introduction of PSiN, the Tmax, IPDT and char yield were all increased. The flame retardancy of PP/PSiN composites was evaluated by measuring the limiting oxygen index values. Thermal stabilities are reported to have agreed with the result of the flame retardancy tests. 37 refs.

Title: COMBINED EFFECT OF NANO-CLAY AND NANO-CARBON BLACK ON PROPERTIES OF NR NANOCOMPOSITES
Page Range: p.709-19
Author(s): Jia Qing-xiu; Wu You-ping; Xiang Ping; Ye Xin; Wang Yi-qing; Zhang Li-qun
File size: 236K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 7

Abstract
Clay/carbon black/NR composites were prepared by adding carbon black in a two-roll mixing mill to clay/NR nano-compounds acquired by co-coagulating clay aqueous solution and NR latex. XRD patterns and TEM observations indicated that both fillers were uniformly dispersed in the rubber matrix at the nano-scale. As a result of the joint effects, with the two fillers benefiting from each other, it was found that at the same total filling amount, those NR nanocomposites filled with both fillers showed advantages over those filled with only one kind. Advantages relate to the enhanced mechanical properties, improved processability, and gas permeability levels near to those of NR/clay nanocomposites. 30 refs.

Title: THE PREPARATION OF CORE/SHELL PARTICLES WITH SILOXANE IN THE SHELL
Page Range: p.721-726
Author(s): Shunsheng Cao; Xiaobo Deng; Bailing Liu
File size: 105K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 7

Abstract
Core-shell microspheres with a polybutyl methacrylate (BMA) core and a poly 3-(methacryloxypropyl)-trimethoxysilane (MATS) shell, were prepared with a methanol as the dispersion medium, by a successive seeding method under kinetically controlled conditions. To prepare core/shell (PA/PSi), the core was first synthesised by dispersion polymerisation and to form seeds. Addition of MATS monomer was started after 90-95% conversion of the BMA. The reaction was prolonged for a further 12 h to achieve complete consumption of the MATS monomer. Microspheres containing hydrophilic PBMA as the core and hydrophobic PMATS as the shell were successfully formed through the free radical of surface in the core. The particle morphology and size distribution were examined using TEM and particle size analysis techniques respectively. 22 refs.

Title: VISCOELASTIC CONSTITUTIVE MODEL OF UNVULCANIZED RUBBER
Page Range: p.727-36
Author(s): Li Yong; Wu Jing'an; Du Xingwen
File size: 224K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 7

Abstract
The rheological properties were examined experimentally using the inner-ply rubber of a bias tyre whose formula contains natural rubber, polybutadiene rubber, styrene butadiene rubber and two types of carbon blacks. On the basis of these rheological test results, a new viscoelastic constitutive equation for unvulcanised rubber has been established, with mathematical justification to describe its mechanical properties in relation to the yield stress and shear-thinning effect. The proposed model indicates that the yield stress is one of the main causes of the shear-thinning effect, and reveals why some materials possess double-Newtonian regions with the shear viscosity in the first region higher than that in the second region. The yield stress makes the flow index of the power law fluid model vary widely, so that it needs to be eliminated from the power law fluid model. The model can also effectively distinguish the true shear viscosity from the apparent shear viscosity, it is claimed. The parameters of the equation are determined by the step fitting method, which is the precondition for quantitative analysis. Since the equation is a one-dimensional model, the authors acknowledge the need for further research. 10 refs.

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