Back SearchTitle: POLYETHYLENE-KEVLAR COMPOSITE FOAMS I; MORPHOLOGY
Page Range: p.279-294
Author(s): Zhang Y; Rodrigue D; Ait-Kadi A
File size: 139K
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Issue Year: cp
Volume: 22
Issue No: No. 5
Abstract
PE-Kevlar composite foams were investigated in order to understand the effect of fibres. In this first part of the study, cell sizes, cell density and cell size distribution of the foams were measured as well as the shear viscosity of the unfoamed composites and matrix. It is shown that the reinforcing fibres are capable of acting as nucleation sites for foaming, depending on the processing conditions of the composites. These results are discussed with reference to fibre content and polymer-fibre interface in relation to the rheological properties of the unfoamed materials. 30 refs.
Title: EVALUATION OF HFC-245FA AS AN ALTERNATIVE BLOWING AGENT FOR EXTRUDED POLYSTYRENE
Page Range: p.295-313
Author(s): Vachon C; Gendron R
File size: 221K
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Issue Year: cp
Volume: 22
Issue No: No. 5
Abstract
This work evaluates the use of HFC-245fa as an alternative blowing agent for use in extruded polystyrene foam and in potential applications for sound insulation board. The process was monitored using ultrasonic probes to reveal information relating to the solubility behaviour of the gas in the molten state. Results showed that at 190 degrees C, HFC-245fa could be incorporated in molten polystyrene up to about 7 wt.%, and generate homogeneous solutions. High concentrations revealed evidence of heterogeneous conditions as seen in the attenuation signal. Three concentrations of blowing agent were used to produce foam samples at lower extrusion temperatures. It was found that by increasing the concentration of blowing agent or nucleating agent greatly affected the expansion profile of the foam samples, and that lower densities could be achieved by using an optimal combination of both. 12 refs.
Title: PP-BLENDS WITH TAILORED FOAMABILITY AND MECHANICAL PROPERTIES
Page Range: p.315-327
Author(s): Reichelt N; Stadlbauer M; Folland R; Chul R; Park C B; Wang J
File size: 127K
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Issue Year: cp
Volume: 22
Issue No: No. 5
Abstract
This study investigates the influence of blending high melt strength PP with a PP block copolymer. The interrelations of blend ratio on the extensional rheology, on foamability, and on the mechanical properties of the finished PP foams are discussed. The resulting foam morphologies of blends consisting of linear and branched PP materials produced at various processing temperatures were studied using a single-screw tandem foam extrusion system and their volume expansion behaviours were compared. A correlation between extensional rheology and lower limit of foam density of blends was found. The influence of foam density and blend ratio on mechanical properties of the foams are discussed with respect to the use of a model and representative samples. 5 refs.