SCF/S₈/PE Rotational Molding Composites With Creep Resistance and Environmental Stress Cracking Property

High-integrity container (HIC) made from polyethylene (PE), operated underground, was subjected to multiple effects, including sustained load creep and environmental stress cracking, which were key factors affecting its useful life. In this paper, a PE rotational molding material incorporating an enhancer of short carbon fiber (SCF) and sulfur (S₈) is designed and prepared. The rotational molding material exhibited good rheological behavior at a temperature range of 200°C–280°C, which meets the requirements of the HIC rotational molding process. The tensile strength, bending strength, and impact strength of SCF/S₈/PE composite were 28.5 MPa, 110.3 MPa, and 110.0 kJ/m², respectively. The extrapolated tensile stress at 300 years was 13.56 MPa, and only 20% of the samples failed (F₅₀) in stress cracking resistance tests after 1000 h in a 10% solution of nonylphenol polyoxyethylene ether at 50°C. In addition, employing basic extrapolation methods based on creep and stress cracking tests, a model was established to predict the fracture time and creep stress duration curves of the composite under low stress conditions.