High-rate thermomechanical behavior of poly(vinyl chloride) and plasticized poly(vinyl chloride)

Abstract

A combined experimental and analytical investigation was carried out in order to develop predictive capabilities for the rate-dependent behavior of poly(vinyl chloride) (PVC) and a dioctyl phthalate (DOP)-plasticized PVC, with focus on predicting the thermo-mechanically coupled behavior under high rates of deformation. The two materials were studied experimentally using both dynamic mechanical analysis (DMA) and compression testing over a wide range of strain rates (10 -4 s -1 to 2000 s -1 ). DMA testing revealed both an α-transition and a low-temperature β-transition (-56°C) in the neat PVC; the incorporation of 20wt% DOP in PVC reduced the α-transition temperature by 54°C, and also suppressed the β-transition peak. In compression testing, rate-sensitivity transitions were observed in both the neat PVC and the PVC-20wt% DOP compound. The transition in PVC is attributed to the shift of the β-transition, whereas the transition in the 20wt% DOP blend is due to the rubbery-to-glassy transition as the deformation rate goes from low to high. A constitutive model for the finite strain deformation of amorphous polymers, introduced elsewhere [1,2] and tailored here for the two material systems of interest, is shown to capture the large deformation stress-strain behavior at all rates tested.