Characterisation of Finite Length Composites

Abstract

Abstract This paper is a technical report about the structure and the rheological behaviour of processed polypropylene-glass fibre composites. The present studies has been carried out as a part of the international project on the Characterization of Finite Length Composites initiated and organized by the IUPAC Working Party: Structure and Properties of Commercial Polymers. Seven industrial and university laboratories in Europe and in USA worked together in a common project to investigate the influence of the processing conditions on the rheology and manufacturing behaviour of polymer-glass composites preprocessed in a twin screw extruder. All investigations presented concern the influence of the processing procedure on the structure of the composites such as fiber length destribution, fiber orientation, destribution of the fibre concentration in the sample and the rheology of the composites. The flow behaviour dependent on the processing conditions has been measured using capillary rheometers to investigate the viscosity functions, the entrance and outlet pressures losses as well as for observations of the shape and internal structure of extruded composites. Torsional rheometers for low shear rate, oscillatory and transient viscosity behaviour and for the quantification of fibre orientation with ongoing shear process. Additionaly queeze flow experiments are made. Most laboratories used analogous recording sytems to documente the primary experimental results. So results are partially given here as direct copies from the original data readings. The different data handling and the transfer of data from laboratory to laboratory for comparison of results leads sometimes to unavoidable inhomogeneous (due to the style and possibilities of the different laboratories) presentation of the results. The present report is a result of data collecting, data comparison and documentation of results over a period of nearly ten years.