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.