温度-应力耦合条件下聚四氟乙烯的压缩蠕变行为与寿命预测

Compression Creep Behavior and Life Prediction of Polytetrafluoroethylene Under Temperature-Stress Coupling Condition

利用自行设计搭建的人工加速老化实验装置,研究了聚四氟乙烯(PTFE)在温度-应力耦合作用下的压缩蠕变行为。结果表明,随温度或应力上升,平衡压缩应变呈增加趋势,该过程以物理老化为主,并伴随晶区分子链螺旋程度降低和片层滑移。以典型实验条件下聚四氟乙烯的非线性蠕变数据为依据,通过构建合适的位移因子,建立了符合广义蠕变柔度曲线的寿命预测模型。进一步选择应变量作为失效判据,合理预测了不同温度条件下材料的压缩蠕变寿命。通过与实验结果比对,证实该模型对聚四氟乙烯寿命预测准确可靠,且对于有类似蠕变行为的高分子材料寿命预测具有一定的普适性和指导性。

The compression creep behavior of polytetrafluororthylene(PTFE)under accelerated coupling aging conditions(temperature and stress)was studied by a homemade apparatus.With the increase of temperature or stress,the equilibrium compression strain increases.The compression creep was mainly dominated by physical aging resulting in the increased crystallinity and decreased degree of helix conformation in the crystal region.Furthermore,the nonlinear creep data of PTFE under typical experimental conditions were used to construct a modified life prediction model based on appropriate shift factor,which works well to the generalized creep compliance curves.The compression creep life under different temperature conditions was predicted reasonably by using strain as failure criterion.This model has a certain universality and guidance for life prediction of polymer materials with similar strain behavior.