Mechanism of rubber elasticity of PP/EPDM thermoplastic vulcanizate

In order to clarify the mechanism of rubbery behavior of thermoplastic vulcanizate (TPV), the deformation and strain recovery behavior of dynamically vulcanized polypropylene (PP)/ethylene-propylene-diene (EPDM) rubber blend was investigated. The deformation of PP matrix in rubber particle circumference was measured in detail by the fixed-region observation of atomic force microscope (AFM) during drawing. Under the small strain, the ligament of plastic phase between rubber particles elastically deformed by bending. Because the bending of thin ligament can be achieved by low stress, it was suggested that the elastic deformation by bending of PP ligament at low stress was the origin of low tensile modulus of TPV. Under the large strain, the PP ligament deformed plastically and buckling of the deformed ligament was observed after releasing the stress. The buckling induced by restorative force of rubber phase was considered to induce the high recovery of TPV.
In order to clarify the mechanism of rubbery behavior of thermoplastic vulcanizate (TPV), the deformation and strain recovery behavior of dynamically vulcanized polypropylene (PP)/ethylene-propylene-diene (EPDM) rubber blend was investigated. The deformation of PP matrix in rubber particle circumference was measured in detail by the fixed-region observation of atomic force microscope (AFM) during drawing. Under the small strain, the ligament of plastic phase between rubber particles elastically deformed by bending. Because the bending of thin ligament can be achieved by low stress, it was suggested that the elastic deformation by bending of PP ligament at low stress was the origin of low tensile modulus of TPV. Under the large strain, the PP ligament deformed plastically and buckling of the deformed ligament was observed after releasing the stress. The buckling induced by restorative force of rubber phase was considered to induce the high recovery of TPV.