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.