摘要
在变形受限条件下,形状记忆热力循环过程中的热应变会显著影响分子链的粘性流动,改变热力过程中的内变量演化机制,从而影响材料本构模型的整体预报精度。为此,结合典型的形状记忆时温历程,首次系统地比较了四种适用于描述非晶态形状记忆聚合物(SMP)热变形模型的预报能力。研究结果表明,由于相变模型不涉及温度变化率和时间迟滞效应,所以无法体现不同变温率条件下的热变形时温历程差异。与之相反,三种结构松弛模型均能准确地反映热变形在降温阶段中受变温率的影响和松弛阶段中随时间的变化。在升温阶段中,结构松弛模型Ⅰ、Ⅲ预报的热变形与降温阶段热变形在玻璃化转变区间出现了变温率相关的分离现象,相比模型Ⅱ更符合理论预期。
On the condition of constrained deformation,the thermal deformation in the thermomechanical shape memory process has distinct effects on the viscous flow of the molecular chains,the evolution mechanism of the internal variables,and the predictability of constitutive models.Therefore,four kinds of thermal deformation models were firstly systematically compared to reveal their predictabilities for a typical time-temperature related process of amorphous shape memory polymers(SMPs).It is found that the difference between the thermal deformations with different temperature changing rates can not be revealed by the phase transition model,for the rate and time-dependent effects are not included in the model.Conversely,the effects of temperature changing rate and time on cooling and relaxing steps can be well described by three structural relaxation models.In the heating step,the thermal deformations simulated by the structural relaxation models I and III have distinctly deviated from the experimental data of the cooling step during glass transition.Compared with the structural relaxation model II,the models I and III are more reasonable for the heating step.
作者
蔡中兵
顾建平
CAI Zhongbing;GU Jianping(School of Civil Engineering,Yancheng Institute of Technology,Yancheng 224051,China;School of Science,Nanjing University of Science & Technology,Nanjing 210094,China;Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology,School of Materials Science and Engineering,Nanjing Institute of Technology,Nanjing 211167,China)
出处
《大学物理实验》
2020年第5期45-51,共7页
Physical Experiment of College
基金
国家自然科学基金资助项目(51808481)
江苏省自然科学基金(BK20170477,BK20170759)
教育部产学合作协同育人项目(201902302027)。
关键词
形状记忆聚合物
非晶态结构
热变形
相变模型
结构松弛模型
shape memory polymer
amorphous structure
thermal deformation
phase transition model
structural relaxation model
作者简介
通信联系人:顾建平。
