Study On The Nonlinear Viscoelastic Behavior Of Eucommia Gum/natural Rubber Vulcanizat

Rubber nanocomposites are the main material of tires,and their viscoelastic properties are closely related to tire processing performance,physical properties and service performance.When subjected to harsh conditions such as high temperature,high frequency,long time,large deformation,etc.,the microstructure,viscoelastic properties and physical and mechanical properties of rubber nanocomposites will undergo significant evolution,resulting in complex nonlinear viscoelastic behavior.,thereby affecting the performance and service life of the tire.In this paper,different proportions of eucommia ulmoides gum(EUG)and natural rubber(NR)combined vulcanizate were used as the research object.The processing properties,crystallization properties and mechanical properties of EUG/NR combined vulcanizates were firstly investigated;then the static and dynamic conditions were systematically studied.The nonlinear viscoelastic behavior of the vulcanizate under the vulcanizate was investigated,and the influence of physical parameters on the viscoelastic behavior of the vulcanizate system was discussed by constructing a viscoelastic constitutive model based on fractional derivatives.The tensile,creep and stress relaxation behaviors of the EUG/NR combined vulcanizate system at different temperatures were studied,and it was found that the EUG content at room temperature was higher than 20 phr and aggregated and formed crystals inside the vulcanizate.With the increase of EUG content,the elongation at break and tensile strength of the vulcanizate decreased,the elastic part of the vulcanizate system increased and the viscous part decreased;with the increase of temperature,the vulcanizate resistance to deformation weakened,the deformation ability increased,and the viscosity increased.ingredients increase.At higher temperature,EUG crystallizes and melts.With the increase of EUG content,the initial modulus of stress relaxation and the modulus when reaching equilibrium both increase,and the elastic part of the vulcanizate system increases;with the increase of temperature,the initial modulus of stress relaxation and When reaching equilibrium,the modulus continued to decrease,and the creep rate and creep deformation gradually increased,the viscous part of the vulcanizate system increased and the elastic behavior weakened.The viscoelastic responses of viscoelastic parameters such as storage modulus,loss modulus and loss factor to the acting frequency,temperature and strain in the EUG/NR combined vulcanizate system were studied.The results show that with the increase of dynamic strain,the storage modulus of vulcanizate decreases sharply and the loss factor increases,and the "Payne" effect appears,and the vulcanizate system changes from elasticity to viscosity;with the increase of temperature,the storage modulus of vulcanizate increases.As the amount decreases,the elastic behavior of the vulcanizate decreases and gradually becomes more viscous.With the increase of the action frequency,the storage modulus of the vulcanizate increases,the elastic part increases and the viscous behavior decreases.The Kelvin viscoelastic model based on fractional derivative is used to analyze the viscoelastic behavior of the vulcanizate system.The results show that the elastic part of the vulcanizate decreases with the increase of temperature,but the viscous part increases with the increase of temperature.The relaxation time shorten.In addition,the static time-temperature equivalent relationship and dynamic frequency-temperature equivalent relationship of nonlinear viscoelasticity of vulcanizate are also constructed,which can calculate the viscoelastic parameters corresponding to the vulcanizate system in a large temperature and frequency range.