A STUDY OF BRITTLE-DUCTILE TRANSITION IN POLYETHYLENE

The brittle-ductile transition temperatures (BDTT) of polyethylenes wi th different degrees of crystallinity, such as LDPE, LLDPE, MDPE, and HDPE, were evaluated using Charpy impact test. The effect of the speci men cooling condition on the BDTT was a main concern in the study. A r ise in the cooling plate temperature (Tp) for high density resins brou ght about a fall in BDTT and an increase in the Charpy impact value Et . However, embrittlement was observed during a tensile test for HDPE s amples with a rise in Tp. A crack shielding effect by microvoid format ion is proposed as the toughening mechanism for HDPE.