摘要
实验测定了 PMMA 在 T=233—343K,(?)=1.0×10^(-6)—1.0×10^(-1)s^(-1)范围内加卸载循环的单轴压缩应力-应变曲线和对应的屈服极大值。按照应力促进热激活过程的绝对反应速率理论,给出了塑性应变率ε_p 的理论表达式,求得过程的热力学特征参数:活化体积 V_a,活化能ΔH 和活化熵ΔS。分析和讨论了ΔH 和ΔS 随 V_a 的变化规律及其物理含义,给出了单一的ΔH 和ΔS 的变化关系。
The uniaxial compression stress-strain curves of loading-and-unloadingcycle and yielding stresses σ_s for PMMA in the ranges of T=233-343K and ε_t=1.0x10^(-4)-1.0x10^(-1)s^(-1) are measured.According to Eyring theory of absolut reaction rates,theexact theoretical formula of plastic strain rates ε_p is proposed.The thermodynamicparameters V_a,ΔH,AS and their curve surfaces changing with condition variables T andlg(?) are determined,and the relationships of ΔH versus V_a,ΔS versus V_a and ΔH versus△S are discussed.
出处
《材料科学进展》
EI
CAS
CSCD
1991年第5期437-442,共6页
基金
浙江省自然科学基金
189023
关键词
有机玻璃
塑性
变形
玻璃态
polymethyl methacrylate(PMMA)
thermally activated plastic deformation
activation volume
activation enthalpy
actcvation entropy
