IMPACT FATIGUE OF SHORT GLASS-FIBER-REINFORCED POLYCARBONATE

The present study analyzes the impact properties of polycarbonate rein forced with 0, 20 and 30 wt% short glass fiber. The specimens were pre pared under various injection molding conditions, such as filling time , melting temperature and mold temperature. Impact tests were performe d with a Dynatup drop weight impact tester at different impact energie s (1.2, 0.16, 0.12 and 0.095 J). The fracture mechanism was examined w ith a scanning electron microscopy. The results indicated that the spe cimen reinforced with 30 wt% short glass fiber showed the highest impa ct energy absorbed, together with the highest impact load in single im pact. The absorbed energy of 30 wt% reinforced is approximately 15% hi gher than that of 20 wt% reinforced and about 10 times higher than tha t of unreinforced polycarbonate. The polycarbonate with 30 wt% short g lass fiber reinforced has the highest impact number and accumulation e nergy in repeated impacts. The accumulation energy is approximately 15 % higher than that of 20 wt% reinforced polycarbonate. The thicker the skin layer, the stronger the interfacial adhesion. The ranking of imp act number and accumulation energy is in goad agreement with the distr ibutions of the skin layer thickness in repeated impacts. The splits a nd tearing mechanisms dominate the single impact fracture in unreinfor ced polycarbonate, while the fiber pull-out and fiber breakage are the major fracture mechanisms in repeated impacts for polycarbonate compo sites.