article

Abstract

Blends (SFRBs) to their melt rheology. These systems consist of Polyamide-6 (PA6) and short Glass Fibre (GF) reinforcement dispersed in a Polyethylene (PE) matrix. An appropriate choice of the components, their interfacial characteristics and the processing route led to the formation of a continuous network, percolating throughout the matrix. The network consisted of fibres (GF) “welded” together by bridges of the dispersed phase material (PA6). A strong strain softening of the melts of the SFRBs was observed at strain amplitudes below 3%, which was absent from their binary equivalents that did not contain the second thermoplastic component.  Based on the specific microstructure of the blends a model is proposed that accounts for this   strain softening behaviour. The model considers the ‘capillary’ forces acting between the fibres participating in the network. These ‘capillary’ forces arise from the deformation of the PA6 bridges that “weld” the fibres together. We propose that the macroscopic deformation process produces points of locally concentrated and magnified deformation, which is sufficient to produce the strain softening of the system. The three parameters that appear in the model have a clear physical meaning. The theoretical results are in good qualitative agreement with the experiments.

© 2007 The Society of Rheology. DOI: 10.1122/1.2409737

polymer 31, 235-260, 2007

The strain dependence of the dynamic moduli of short fibre reinforced thermoplastic blends