Strain Rate and Coupling Agent Effects in Discontinuous Glass Fiber Reinforced Polypropylene Matrix

Mechanical tensile behaviour studies are reported for discontinuous glassfibers 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-sec- 1 to 10 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.