Relationship Between Slow Crack Growth Resistance Performance and Thermal Fractionation Characterization of Polyethylene Based on Strain Hardening Modulus

The slow crack growth resistance of four polyethylene pipe materials was characterized by strain hardening modulus， successive self-nucleation and annealing fractionation （SSA）， and temperature rising elution fractionation （TREF）. The correlation between strain hardening modulus and thermal fractionation was investigated. The strain hardening modulus of polyethylene can effectively reflect the performance of the raw material in resisting slow crack growth. The strain hardening modulus of PE100-RC grade is the highest， while that of PE80 grade is the lowest. The results of SSA and TREF show consistency. SSA is within 135 ℃， and TREF is within the range of 90~105 ℃， the grade content is positively correlated with the strain hardening modulus of the polyethylene pipe material special grade. The slow crack growth resistance of the polyethylene pipe materials can be qualitatively assessed by the content of high-temperature crystalline fractions obtained from both methods. The SSA method offers advantages in terms of equipment， test cycle of 4 hours， sample consumption， and environmental friendliness.