Published by De Gruyter

Volume 2 Issue 4

August 1987

Issue of International Polymer Processing

Contents
Journal Overview

Publicly Available April 9, 2022

Page range: 155-155

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Original Contributions

April 9, 2022

The Processing Science of Thermoplastic Structural Composites

F. N. Cogswell

Page range: 157-165

Abstract

A sound scientific basis for understanding what happens during the processing of materials, and how that stage affects the service performance of the structure, is an essential prerequisite to the development of efficient low cost fabrication technology. This paper considers the phenomena – chemical, thermal, thermodynamic and rheological – which occur during processing and reviews the information which we have available today as a basis on which to build a more comprehensive study and data base.

April 9, 2022

Simulation of Balancing Multi-Cavity Molds

H. Ghoneim

Page range: 166-173

Abstract

A finite element program is developed for simulating the non-isothermal flow of non-Newtonian liquids in a multi-cavity mold with convergent runners and gates of any arbitrary cross-sectional shape. The program is used to investigate the problem of balancing multi-cavity molds. Results of simulating an actual mold filling show that balancing can be achieved by using a straight runner together with convergent gates having successively increasing angles of convergence. In addition, a strategy for approximating those angles of convergence is suggested.

April 9, 2022

Effect of High Molecular Mass Tail in the Mol Mass Distribution of Polypropylene on Injection Molding

R. Qian, M. Guo, S. Li

Page range: 174-178

Abstract

The effect of high molecular mass (MM) tail in the molecular mass distribution (MMD) of polypropylene (PP) on injection molding has been studied using injection molded tensile bars from a commercial PP resin and two samples of the above resin deprived of the high MM tail in different degrees by controlled degradation during extruder reaction with an added processing aid named Promax. The central portions of the tensile bars were studied by polarizing microscopy of microtomed sections parallel and perpendicular to the melt flow direction, and by density and birefringence profiles across the thickness of the bar. Mechanical properties and acoustic emission behavior in stretching of these injection molded tensile bars are also discussed. The experimental results show that by stripping off the high MM tail in the MMD the injection molded tensile bar has smaller degree of crystallization, less frozen orientation, improved uniformity across the thickness and the thickness of the skin part is greatly reduced. Better quality of the fabricated articles is to be expected by using Promax with PP for injection molding.

April 9, 2022

Flow Visualization Parallel and Perpendicular to the Rotor Axes for Elastomers and Molten Plastics in an Internal Mixer*

The Influence of Rotor Design

K. Min

Page range: 179-187

Abstract

Basic studies of flow visualization for elastomers and plastics in an internal mixer are described. A modified laboratory mixer with transparent front and trasverse windows was used to observe parallel and perpendicular motions. Shearing, stretching and tearing motions were observed especially for elastomers. Various rotor designs were used. These indicate different flow fields along the rotor axes, and the interchange of materials between rotors. We describe the different flow fields observed for elastomers and plastics creasted by various rotor designs.

April 9, 2022

Shear Modification of Polyolefines and its Integration in Polymer Processing

G. Ritzau

Page range: 188-197

Abstract

The viscous and especially the elastic properties of polymer melts can be altered by a previously imposed deformation history. This phenomenon, usually termed as shear modification, is caused by the reversible physical disentanglement of the polymer molecule chains. The shearing unit presented in this paper was used to systematically investigate the processing parameters governing shear modification. A set of rheological tests was carried out with the shear modified sample material and the expected changes in the rheological behaviour were detected. The relative change of the storage modulus G’, measured using a Rheometrics On-line Rheometer system, was taken as a measure for the degree of modification and was found to correlate with the specific energy dissipated during sample preparation. The effects of shear modification on product properties were investigated for the tubular film-blowing process. Changes in the optical and mechanical properties of films which can be attributed to the previously imposed shear modification process were found.

April 9, 2022

Recent Studies on Degradation Mechanism of Rubber Vulcanizates by Chemorheology

K. Murakami

Page range: 198-206

Abstract

A critical discussion is presented of the influence of chemical degradation mechanisms on the mechanical properties, especially stress relaxation, of vulcanized rubber. The response of the vulcanizate is interpreted in terms of the kinetic theory of rubber elasticity. Different chemical mechanisms are explored. The influence of diluent is interpreted in terms of the kinetic theory of rubber elasticity. Different chemical mechanisms are explored. The influence of diluent is considered. Comparisons are made to experiments on polyisoprenes and polyurethanes.

April 9, 2022

Modelling Flow in an Intermeshing Co-rotating Twin Screw Extruder: Flow in Kneading Discs

W. Szydlowski, R. Brzoskowski, J. L. White

Page range: 207-214

Abstract

A model for simulation of flow in an intermeshing kneading disc region of corotating twin screw extruder is presented. This is based on hydrodynamic lubrication theory for a Newtonian fluid. Numerical procedures are used to compute the pressure distribution and flow field in the kneading disc region. The influence of staggering angle, nip clearance, screw speed and throughput rate are investigated.

About this journal

International Polymer Processing offers original research contributions, invited review papers and recent technological developments in processing thermoplastics, thermosets, elastomers and fibers as well as polymer reaction engineering. For more than 25 years International Polymer Processing, the journal of the Polymer Processing Society, provides strictly peer-reviewed, high-quality articles and rapid communications from the leading experts around the world.
All articles are subject to thorough, independent peer review.
Editor: Polymer Processing Society

Volume 2 Issue 4

Issue of International Polymer Processing

Contents

The Processing Science of Thermoplastic Structural Composites

Abstract

Simulation of Balancing Multi-Cavity Molds

Abstract

Effect of High Molecular Mass Tail in the Mol Mass Distribution of Polypropylene on Injection Molding

Abstract

Flow Visualization Parallel and Perpendicular to the Rotor Axes for Elastomers and Molten Plastics in an Internal Mixer*

The Influence of Rotor Design

Abstract

Shear Modification of Polyolefines and its Integration in Polymer Processing

Abstract

Recent Studies on Degradation Mechanism of Rubber Vulcanizates by Chemorheology

Abstract

Modelling Flow in an Intermeshing Co-rotating Twin Screw Extruder: Flow in Kneading Discs

Abstract