环氧形状记忆聚合物的热力学性能试验研究

Experimental study on thermodynamic performance of epoxy shape memory polymer

针对目前关于形状记忆聚合物热力学性能研究不足,本文对一种新研制的环氧形状记忆聚合物开展了三类热力学试验。首先进行了SMP拉伸、弯曲、扭转形变下的形状记忆自由回复试验,测定了形状记忆固定率与回复率,均可达到99. 4%以上;采用热分析仪测定了材料-50℃～100℃的热膨胀应变随温度的关系,其值呈近似双线性,在玻璃转换点前后分别为4. 8×10^(-5)℃和2. 76×10^(-4)℃;最后进行了不同温度时的拉伸应力松弛试验及其不同加载速率拉伸试验,结果表明:在玻璃化转变温度附近,材料弹性模量与应力松弛现象发生明显的改变,形状记忆聚合物具有较强的时温相关非线性粘弹塑性力学行为特征。

Considering the lack of thermodynamic performance research on shape memory polymers(SMPs),three kinds of thermodynamic experiments were performed on a newly developed epoxy SMP.First,a shape memory free recovery experiment was carried out under the tensile deformation,bending,and torsion of the SMP.The fixing rate and recovery rate were tested,and they both exceeded 99.4%.Then,a thermal analyzer was used to test the change of thermal expansion strain with the temperature of the material from-50℃to 100℃.The thermal expansion coefficient was approximated to be bilinear,and was 4.8×10-5℃and 2.76×10-4℃before and after the phase transition point,respectively.Finally,a tensile relaxation test under different temperatures and tensile tests under different loading rate were carried out.The results reveal that the SMP elastic modulus and stress relaxation significantly changed near the phase transition temperature,and SMPs exhibits strong time-temperature-dependent nonlinear viscoelastic and plastic behaviors.