纤维增强形状记忆聚合物复合材料的热变形行为

Thermal Deformation Behaviors of Fiber Reinforced Shape Memory Polymer Composites

通过将热力学内变量理论与Adam-Gibbs结构松弛模型相结合的方法,构建了适用于描述非晶态形状记忆聚合物(SMP)玻璃化转变过程中热变形行为的模型。在此基础上,利用复合材料细观力学分析方法进一步建立了纤维增强形状记忆聚合物复合材料(SMPC)热膨胀系数模型。模型中考虑了温度变化对基体弹性模量和泊松比在玻璃化转变过程中的影响。研究了一种含T300碳纤维增强相SMPC的热变形行为,结果表明,SMPC的各向热应变在升降温阶段几乎一致,仅在玻璃化转变附近微小分离;较快降温率导致的低温态热应变略小,而较快升温率导致平衡态温度更高; x向热应变随纤维倾角增大而增大,随纤维含量增大而减小。研究结果可对纤维增强SMPC的设计与应用提供一定理论参考。

A thermal deformation model incorporated with an internal state variable modeling approach based on thermodynamics and Adam-Gibbs structural relaxation model was developed for amorphous shape memory polymers（SMPs）in the paper. The model can be used to capture the material thermal deformation behavior in the glass transition. Then the thermal expansion coefficient model of fiber reinforced shape memory polymer composites（SMPCs） was proposed based on the mesoscopic mechanical analysis. In the model,the temperature dependence of the elastic modulus and Poisson＇s ratio of the SMPs was taken into consideration. The thermal deformation of the SMPC which was reinforced with carbon fiber T300 was studied. It is found that thermal deformations in different directions are almost the same during heating and cooling,except a slight difference in the glass transition. The thermal deformation in the glassy state decreases with the increase of cooling rate,and the equilibrium temperature increases with the decrease of heating rate.Besides,the thermal deformation in x direction increases with the increase of the fiber orientation,while it decreases with the increase of the fiber volume content. Therefore,the guidance for design and application of fiber reinforced SMPCs can be provided by the research findings of the paper.