热塑型聚氨酯弹性体的极限断裂强发动力学模型理论

本文提出了一种等速拉伸下聚氨酯极限断裂强度动力学模型理论,它从聚氨酯大形变弹性理论出发,将单向拉伸应力-应变关系同应力集中链的断链动力学方程相结合,推导出了应力集中链的断链动力学方程,积分和化简后得到了极限断裂强度同断裂伸长,链结构参数和测试条件(温度和拉伸速率)间的定量关系式。在实验上又分别考虑了W_k,_(ns)、T和k_λ~·等对极限断裂力学性能的影响。并以大量实验数据对理论进行了验证,得到理论同实验较好地一致。成功地把聚氨酯网络结构同极限断裂力学性能联系起来,为预测聚氨酯极限断裂力学性能和建立它们的破裂包络线提供了理论基础。

A Kinetic Model Theory for Tensile ultimate Strength of Thermoplastic Polyurethane Elastomers

A new kinetic model theory for tensile ultimate strength of thermoplastic polyurethane elastomers was proposed. It is based on the theory of the Eyring chemical activation rate and that of rubber elasticity at large deformation. A kinetic equation for bond rupture of overstressed polymer chain is established by employing the coefficient and stress of overstressed chain as variable. By integration and simplification a new correlation of the tensile ultimate strength with the extensibility, the parameters of structure, the temperature, and the extension rate was quantitatively derived. The dependence of fracture properties on the contents of hard segments, the primary molecular weight of soft segments and the strain rate were studied, hy uniaxial extension method. The proposed theory was verified by the experimental data of ultimate properties. The results show that the proposed theory can predict the failure behavior of thermoplastic polyurethane elastomers and provide a theoretical foundation for construction of failure envelope.