聚脲弹性体力学性能与本构关系研究进展

聚脲是一种由异氰酸酯组分和氨基组分反应生成的新型弹性体高聚物.由于聚脲具有断裂伸长率高、应变率强化、高耗能等一系列优异的力学性能,其在国防、能源、交通等领域显示出广阔的应用前景.目前,国内外学者针对聚脲在不同温度、不同应变率下的静动态力学性能开展了大量研究,在此基础上提出了多种本构模型,对温度、应变率等因素相关的力学行为进行了描述和预测.这些工作为深刻理解聚脲抗冲击机理及材料的进一步应用奠定了基础.文章首先简要介绍了聚脲弹性体的微相分离结构及特点;然后从小变形线性黏弹性和大变形非线性黏弹性两个方面概述了关于聚脲力学性能的研究,包括相应测试技术的发展和聚脲黏弹性影响因素的研究;进一步从变形梯度乘法分解法、遗传积分法、应变-时间解耦法等不同建模方法出发对已建立的聚脲本构模型进行综述,并从应变率范围、温度范围、压力相关性、软化行为表征及模型参数数量的角度对比了不同类型模型的区别;最后针对聚脲力学性能与本构关系下一步研究值得重点关注的问题提出了几点建议.

REVIEW ON MECHANICAL BEHAVIOR AND CONSTITUTIVE RELATION OF POLYUREA ELASTOMER

Polyurea is a new type of elastomeric polymer which is formed through the reaction of isocyanate components with amine components. Due to its excellent mechanical property, such as high elongation, high strain rate strengthening and high dissipation, polyurea shows a broad application prospect in the fields of national defense, energy resources and transportation. So far, numerous studies on the static and dynamic mechanical properties of polyurea under multiple temperatures and strain rates have been performed. Various constitutive models were established to characterize and predict its mechanical behavior concerning its temperature dependence, strain rate dependence and other mechanical characteristics. These researches provide a foundation for understanding the anti-impact and shock attenuation mechanism of polyurea, as well as its further application. Firstly, the micro-phase segregated structure of polyurea is introduced briefly in this paper. Then we review the experimental researches on the mechanical behavior of polyurea from the perspectives of linear viscoelasticity under the small deformation and nonlinear viscoelasticity under the large deformation, including the development of testing technology and the researches on the factors influencing the viscoelasticity of polyurea. In addition, the constitutive models of polyurea, established through the framework of multiplicative decomposition of deformation gradient, the approach of hereditary integral, the strain-time decoupling approach or other modelling approaches, are reviewed. The differences between different types of models are discussed from the perspectives of strain rate range, temperature range, whether the model could describe the pressure dependence and softening behavior of polyurea, and the number of model parameters. Finally, several suggestions for further research on the mechanical behavior and the constitutive relation of polyurea are put forward.