PP/PA共混高聚物在高应变率下的热粘弹性本构关系和时温等效性

采用Instron1342电液伺服试验机和改进的SHPB技术对以113材料为例的PP/PA共混高聚物进行了应变率在10-4~103 s-1宽广范围，温度为25、40、60、80 ℃下的一维应力力学性能试验。结果表明,这类共混高聚物的力学响应对温度和应变率都是敏感的。以朱-王-唐非线性粘弹性本构方程来描述这类PP/PA共混高聚物的力学响应，并拟合得到了其热粘弹性本构参数，理论预言与试验结果在应变小于7%时吻合良好。对113材料20~80 ℃温度范围内不同应变率下的试验结果进行分析，证明PP/PA共混高聚物存在率温等效关系，提高温度和增加作用时间（减小应变率）的效果相当，反之，降低温度与减少作用时间（提高应变率）的效果相当。通过引入量纲一参量Z，使应变率d/dt、温度T这2个参量归结为统一的Z参量，从而得到了体现时温等效性的统一曲线。

Thermoviscoelastic constitutive equation of PP/PA blends and its rate-temperature equivalence relation at high strain rates

By using Instron 1342 testing system and an improved SHPB technique, PP/PA blends were tested at a wide range of strain rates from 10^-4 up to 10³ s^-1 and at a temperature range of 25~80 ℃. Their mechanical responses are shown to be sensitive both to the strain rate and temperature. Based on the experimental data of 113 blends at a wide range of strain rates from 10^-4 up to 10³ s^-1 and at a temperature range of 25~80 ℃, it is shown that the mechanical behavior of this PP/PA blends can be described with ZWT thermoviscoelastic constitutive equation. The corresponding thermoviscoelastic parameters for 113 blends were obtained. The predicted theoretical results coincide quite well with the experimental data. The experimental results also reveal the time-temperature equivalence relation for PP/PA blends. Raising the temperature is equivalent to the increasing of time (the decreasing of strain rate). Conversely, decreasing the temperature is equivalent to the decreasing of time (the increasing of strain rate). Through introducing a dimensionless parameter Z=(dε/dt)η₀exp(A/kT)/E, two characteristic parameters: strain rate =(dε/dt) and temperature T are put together to this unified parameter Z. From experimental results, A/k was fitted, A/k=8.595 ℃, and a unified curve characterizing the-time temperature equivalence relation was obtained.