The correlation of slow crack growth in linear polyethylene by the J-integral

The fracture of a polyethylene (PE) homopolymer by slow crack growth was measured with a three point bending (TPB) specimen and a single edge notch tension (SENT) specimen. The crack growth rate correlated with the stress intensity for each type of specimen. However, for a given K, SENT specimens exhibited a faster crack growth rate than TPB specimens. Since PE is non-linear, the J-integral is more appropriate than K and it was found that J does correlate the SENT and TPB results. In addition, the degree of non-linearity of the PE was increased by quenching. For the quenched state it was also found that J correlated the SENT and TPB results in accordance with the dependence of J on the degree of non-linearity of the material.