Long-term tensile creep behavior and stochastic Larson–Miller life prediction of commercial ABS and HIPS grades for household appliance applications

The long-term reliability of styrenic polymers used in household appliances cannot be reliably assessed by mean rupture life alone, as deformation behavior and lifetime distribution may vary simultaneously under different applied stress–temperature conditions. To address this limitation, the long-term creep behavior of four household-appliance styrenic materials, namely ABS 1, ABS 2, HIPS 1, and HIPS 2, was analyzed by constructing a failure mechanism map (FMM). Here, ABS 1 and HIPS 1 denote the neat base materials, whereas ABS 2 and HIPS 2 denote additive-blended grades designed to improve weatherability and material performance, respectively. In parallel, an Arrhenius-type Norton power-law model was applied to the minimum steady-state strain rate, and Larson–Miller-parameter (LMP)-based mean-life and probabilistic master curves were developed for rupture-life prediction. The results revealed that the ABS-based materials exhibited increasingly ductile fracture behavior with rising temperature, while the HIPS-based materials exhibited more brittle fracture characteristics. Correspondingly, the blend materials exhibited fracture-mode transitions distinct from those of their neat counterparts, indicating that multiphase structures and interfaces may influence damage initiation and propagation. Moreover, the probabilistic LMP master curve quantified both mean life and lifetime scatter, thereby enabling a more refined comparison of the long-term reliability of neat and blend materials. Overall, these findings indicate that long-term creep reliability assessments of polymers for household appliance applications should consider not only mean rupture life but also deformation trends, fracture-mode transitions, and lifetime scatter. In this context, the present study, involving FMM-based fracture analysis and probabilistic LMP master-curve modeling, provides a practical framework for comparing the long-term durability of neat and blend materials and for establishing allowable-stress design under long-term service conditions.