Response of Mechanical Properties in PVC-P GMB to Tensile Rate and Low Temperature

Plasticized polyvinyl chloride (PVC-P) geomembranes (GMBs) are widely used in cold regions as impervious barriers, facing combined low-temperature and variable loading effects. However, design specifications rely on room-temperature tests at fixed rates, not reflecting actual conditions. This study systematically investigates the axial tensile properties of a 1.5 mm thick PVC-P GMB across eight temperatures (−40 °C to 20 °C) and five tensile rates (1–100 mm/min). A total of 211 uniaxial tensile tests were conducted using a low-temperature system with a servo-hydraulic machine and DIC extensometer. Nominal and true stress–strain curves were analyzed. Results show that fracture strength, fracture strain, and elastic modulus are highly sensitive to temperature and tensile rate, with a pronounced coupling effect between these two factors. Lower temperatures increase fracture strength and elastic modulus but reduce fracture strain, leading to brittle transition at −40 °C, especially at high rates. The fracture strength, fracture strain, and elastic modulus all increased with tensile rates at low tensile rates (1–20 mm/min). However, negligible difference in these parameters at high rates (20–100 mm/min) was observed. Elastic modulus follows a Boltzmann function with temperature, and fracture strain linearly correlates with temperature (R2 > 0.93). The mechanical properties measured at room temperature overestimate the deformability at low-temperature and hence underestimate the brittle failure risk. Therefore, future cold-region testing should adopt tensile rates of 10 or 20 mm/min, and temperature-rate coupled constitutive models should be developed. These findings provide essential data and guidance for material selection, design, and standard revision for PVC-P GMBs in cold-region applications.