Polymer Journals

Polymers and Polymer Composites

Logged into APC, CP, IPSAT, PPC, PRR, RRR & PRPRT.

Back  Search



Title: HEAT STABILITY AND DEGRADATION OF THERMALLY STABLE PREPOLYMERS IN A CONTROLLED ATMOSPHERE. III. THERMAL HOMOPOLYMERIZATION CYCLE OF DICYANATE MONOMERS AND PHYSICOCHEMICAL CHARACTERIZATION OF THE CROSSLINKED SYSTEM
Page Range: p.431-448
Author(s): Richer S; Alamercery S; Delolme F; Dessalces G; Paisse O; Raffin G; Sanglar C; Waton H; Grenier-Loustalot M F
File size: 325K
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 9
Issue No: No. 7

Abstract
The development is discussed of high temperature formulations containing cyanates for use in electronics and structural composites. In order to overcome difficulties relating to the use of thermally stable polymers, it was necessary to develop a hydrophobic matrix. After characterisation of the dicyanate monomers of bisphenol A and hexafluorobisphenol A, the molten state mechanisms and kinetics of homopolymerisation of the prepolymers were studied in order to characterise the side products formed during heat treatment. This was achieved by a detailed physicochemical study and by monitoring the changes over time in controlled conditions of temperature and atmosphere. Using a range of techniques for kinetic and mechanistic monitoring in solution and in the solid state after formation of the network, a thermal cycle was validated with respect to the optimal properties of the system. A comparative study of the chemical and thermal behaviour of the two monomers was carried out to determine the effect of the central pivot bond on the thermal properties of the crosslinked materials. 21 refs.

Title: MICROSTRUCTURAL CHARACTERISATION OF A SYNTACTIC FOAM
Page Range: p.449-458
Author(s): Lawrence E; Wulfsohn D; Pyrz R
File size: 159K
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 9
Issue No: No. 7

Abstract
The use of design based stereological methods to quantify the microstructure of syntactic foam, including the interpretation of statistical results for the design of the experimental protocol is presented. The foam, formed by extrusion, consisted of hollow polymeric microballoons in a LDPE matrix. Estimates of cell volume fraction, number density and the mean and standard deviation of volumes of cells were made, and the distribution of cell aspect ratio was estimated, assuming ellipsoidal cells with the major axis in the direction of extrusion. 18 refs.

Title: EFFECT OF THE VULCANIZING SYSTEM OF CURE AND MECHANICAL PROPERTIES OF NBR/EPDM BLENDS
Page Range: p.459-468
Author(s): Oliveira M G; Soares B G
File size: 100K
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 9
Issue No: No. 7

Abstract
The effect is investigated of the choice of vulcanising system on the curing parameters and mechanical properties of NBR/EPDM blends. The curing characteristics of the blends were shown to be affected by the accelerator type and the sulphur concentration. Sulphur/benzothiazyl-disulphide and single and binary accelerator systems based on tetramethyl thiuram disulphide were investigated. Higher thermal stability was achieved in blends containing higher levels of sulphur, due, it is thought, to increased crosslinking in the EPDM phase. Results of dynamic mechanical investigations showed differences in Tgs, which increased with increasing the sulphur contents in both vulcanising systems. 27 refs.

Title: SYNTHESIS AND PROPERTIES OF POLY(ACRYLIC ACID)/MONTMORILLONITE SUPERABSORBENT COMPOSITES
Page Range: p.469-472
Author(s): Lin J; Wu J; Yang Z; Pu M
File size: 48K
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 9
Issue No: No. 7

Abstract
A novel superabsorbent polyacrylic acid/montmorillonite composite with absorbency of about 1100 times its own weight, was synthesised by graft copolymerising acrylic acid onto ultrafine montmorillonite powder. The influence is investigated of the amount of crosslinker, montmorillonite and the degree of neutralisation on the water absorbency of the composites. 6 refs.

Title: PLASTIC DEFORMATION OF FIBROUS POLYMERS VIA WEIBULL MODEL
Page Range: p.473-482
Author(s): Juhar G; Saqan S; Zihlif A M
File size: 105K
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 9
Issue No: No. 7

Abstract
A study is presented of the plastic deformation of Kevlar fibres, PAN-based carbon fibres and PP fibres of different gauge lengths. An attempt is reported to fit the Weibull model to the deformation behaviour of these fibrous polymers. A statistical analysis for the fibre strength and breaking strain is presented to test the experimental data relating to the fibre deformation. Mechanical parameters such as fibre strength, breaking strain and Young's modulus are studied as a function of gauge length. The output of the analysis is claimed to support the concept that the Weibull model is a good technique to specify the statistical distribution for strength and breaking strain of fibres, and is suitable to investigate the mechanical behaviour of fibrous polymeric materials in general. 16 refs.

Title: POLYMERS FROM RENEWABLE SOURCES: EFFECTS OF ZINC CHLORIDE ON KINETICS OF GAMMA-IRRADIATION INDUCED GRAFTING OF STYRENE AND ACRYLONITRILE OTO EXTRACTED CELLULOSE
Page Range: p.483-486
Author(s): Chauhan G S; Chauhan S; Guleria L K
File size: 48K
Download the pdf (subscribers only)
Buy the pdf (non-subscribers)
Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 9
Issue No: No. 7

Abstract
Cellulose extracted from pine needles was graft copolymerised with styrene and acrylonitrile, and the effect of zinc chloride, when used as a complexing agent, on the grafting parameters was studied under optimum reaction conditions using the co-monomer concentration that gave the highest level of grafting. Zinc chloride is shown to affect the grafting on to cellulose, especially for polar monomers, by decreasing its crystallinity and making the backbone accessible to the reacting species. It also forms a donor-acceptor complex with polar monomers and hence activates them for grafting. Graft copolymers were characterised by elemental analysis and FTIR to provide evidence of grafting and to investigate the structure of the grafted chains. 6 refs.

%>