摘要
Polystyrene (PS) is a thermoplastic with a variety of applications in packaging, electronics, automotive, and so forth. Its mechanical strength determines the structural integrity of PS‐based structures and devices under various conditions. In this work, we analyzed the correlations between the moisture uptake, incubation time, surface cracking, and mechanical strength in a‐PS films. The moisture uptake results in an increase in the surface energy, which facilitates the nucleation and propagation of surface cracks and causes a decrease in the fracture strength. Surface cracking on the a‐PS surface occurs only following moisture ingress, after a measurable incubation period. According to the experimental results, we assume that the crack density is a power function of the moisture amount absorbed by the a‐PS films. Using the power function to fit the experimental results, we determine both the activation energy and the enthalpy of mixing controlling the kinetics of the moisture‐induced surface cracking and obtain a power index of 1. The moisture uptake follows the anomalous transport in the a‐PS films. The observed linear correlations between crack density and nominal surface energy, as well as between crack density and fracture strength in the moisture‐treated a‐PS films, indicate that the nominal surface energy likely correlates with crack density and fracture strength under the investigated conditions. Highlights Moisture transport in a‐PS films is anomalous. Moisture raises surface energy, aiding crack formation. Cracks appear only after moisture ingress and incubation. Crack density scales with absorbed moisture amount. Crack density links linearly to strength and surface energy. Moisture uptake induces surface cracks in PS films. Fracture stress decreases linearly with crack density, with higher temperatures accelerating the rate of decline.