Tokové chování a degradace vláken během smykového toku PP kompozitů

Abstract

V této práci byl sledován vliv pevnosti vláken na viskoelastické vlastnosti PP kompozitů. Jako plnivo byla použita uhlíková vlákna. Bylo zjištěno, že flexibilita vláken se v kompozitech uplatňuje zejména při nižších deformacích. Koncentrace plniva má značný vliv na parametry modelů popisujících vztahy mezi viskoelastickými funkcemi a obsahem vláken.

The processing of fibre-reinforced thermoplastics is often accompanied by a significant fibre fracture. Therefore, it is important to assess the effect of processing variables on the extent of fibre degradation occurring during a product fabrication, such as extrusion or injection moulding. The present paper discusses fibre damage caused by shear forces exerted on the composite by molten matrix in both experimental and theoretical terms. The degradation process in carbon fibre/polypropylene composites is studied in a broad range of shear rates, although it occurs significantly only under high shearing in the capillary. Changes in fibre length and its distribution during the multi-flow through the capillary, and rheological properties of the materials after shearing found in the research, are discussed and the results are compared with a model of fibre length analysis for mixing/regrinding process.