The effect of glass fibers on the resistance to slow crack growth in polypropylene molded pieces

Slow crack growth was studied in molded pieces of virgin Malen P J-400 and of glass fiber-reinforced (10%) Malen P J-400 polypropylene (PP) (Xenopren PPGF10-CC composite). The Xenopren PPGF10-CC composite samples were examined for 264-1104 h and showed a reduced resistance (Table 2, Fig. 8). The virgin PP samples did not crack in 1000 h, presumably because the stress cracks propagating along the load axis (cf. [18]) augmented the tendency to plastic deformation and prevented the fracture.