Ductile‐brittle transition behavior of short‐chain branched polyethylenes at 80°C

Abstract

AbstractA systematic study on the ductile‐brittle transition of short‐chain branched polyethylenes (SBPEs) is reported. The values of threshold stress intensity, the time corresponding to the point of ductile‐brittle transition and the failure time (tf) of samples which failed in ductile and brittle regions were found to increase significantly with increasing branch length of the SBPEs. The fracture kinetics and the morphology at the notched root were distinguished for SBPE samples that failed in ductile and brittle regions. The values of (CC(notch opening displacement at the roof of notch)–BB(the thickness of the craze))/(AA(notch opening displacement at the surface of the specimen)–CC) are less than or equal to about 0.3 for all samples which failed in the brittle region, and these values are only about 20–30% of those of the samples which failed in the ductile region. Finally, an equation was developed to predict tf of SBPEs which failed in the ductile and brittle region in terms of stress intensity, branch length and other material and experimental parameters.