Rate dependence of poly(vinyl chloride), the effects of plasticizer and time–temperature superposition

Abstract

Four different poly(vinyl chloride) (PVC) materials varying in plasticizer content were studied in a combined experimental and analytical investigation including uniaxial compression tests at strain rates ranging from 10 −3 to 10 4 s −1 at room temperature, and temperatures ranging from −115 to 100 • C at a rate of 10 −2 s −1 . Additional tests using a dynamic mechanical and thermal analyser were conducted on each PVC material to give a more detailed analysis of temperature and rate dependence. Adjusting the plasticizer content allows the temperature at which transitions, specifically the α-transition, or 'glass transition', and β-transition, occur to be moved in order to better examine the interplay of temperature and strain rate dependence. This program of research is then extended to time-temperature superposition where a novel application and interpretation of an established superposition method is presented.

High Strain Rate Mechanics of Polymers: A Review

“…where A quantifies the interaction between rate and temperature and maps from a temperature T to a new temperature T 0 and mapping the strain rate from _ e 0 to a new strain rate _ e. The mapping parameter, A, may be considered as the temperature-strain rate equivalence parameter, which relates equivalent stress states in the material and is agnostic to the underlying deformation mechanisms [185] and it is typically found by fitting temperature dependent and rate dependent yield data but, in principle, should be obtainable from Dynamic Mechanical Analysis (DMA) data, and is certainly consistent with these data [153]. Siviour's formula was able to capture several changes deformation mechanisms which govern changes in yield stress, including the inflection in data which involves the glass transition PVDF, and that which is understood as the beginning of the b-transition in PC.…”

“…Materials which have been well-studied in the literature are silicone elastomers [13,66,151], plasticized PVC [152,153] and polyureas [39,40,72,[154][155][156][157][158][159] and polyurethanes [160][161][162]. The rate dependence of these materials depends strongly on the glass transition, and in particular whether this transition affects the room temperature response at strain rates of interest.…”

“…This analysis has subsequently been used on semi-crystalline polymers [174,178] and particulate composites [41,186]. Recent data on PVC with different amounts of plasticizer [153] have shown the effects on the analysis of having two transitions influencing the rate dependence, and how this can be dealt with using two shift parameters, similar to the deconstruct, shift, reconstruct method pioneered by Mulliken and Boyce [20], discussed further below. Brown et al [178] provided a detailed analysis of the linear mapping proposed Siviour [19] starting in the context of polymers with linear rate and temperature dependence but drawing conclusions applicable to all polymers.…”

“…7 Plasticized PVC a stress-strain relationship at different strain rates and b representative stress close to yield as a function of strain rate. Data from [153] using a Split Hopkinson Pressure Bar (SHPB) and observed an increase in the rate dependence of the yield stress above approximately 100 s -1 at room temperature. Walley and Field [5] studied several polymers, focusing on rate-dependent behavior.…”

Impact behaviour of an innovative plasticized poly(vinyl chloride) for the automotive industry

“…Kendall and Siviour [6,7] investigated the mechanical response of a PPVC under uniaxial compression, with a high level of plasticizer, from quasistatic to dynamic loadings at room temperature. At high strain rates, the PPVC exhibits a viscoelastic-viscoplastic response.…”