STRAIN-RATE AND COUPLING AGENT EFFECTS IN DISCONTINUOUS GLASS-FIBER-REINFORCED POLYPROPYLENE MATRIX

Mechanical tensile behaviour studies are reported for discontinuous glass-fibers reinforced polypropylene matrix. Samples were prepared by varying fiber/matrix coupling agents. The influence of strain rate on mechanical properties was analyzed in low and moderate (10(-3) sec-1 to 10(3) sec-1) strain rate ranges. It was found that (1) in the moderate strain rate range, optical extensometry is invaluable in determining the actual specimen strain, (2) a drastic transition of mechanical tensile behaviour occurs with increasing strain rates, and (3) fiber/matrix coupling agents affect particularly stress-strain behaviour in the moderate strain rate range. A strong interfacial bond seems to improve the ability of the fibers to take up load in regions of matrix cracking; this leads to higher tensile strength.