Strengthening effect of Mullins effect of high- density polyethylene/ethylene-propylene-diene terpolymer thermoplastic vulcanizates under compression mode

Thermoplastic vulcanizates (TPVs) based on high-density polyethylene (HDPE)/ethylene-propylene-diene terpolymer (EPDM) were prepared via dynamic vulcanization. The mechanical properties and strengthening effect of Mullins effect under compression mode were investigated systematically. Experimental results indicated that the compression strength of TPVs was enhanced greatly compared with that of EPDM vulcanizate. Mullins effect could be observed obviously in the compression stress-strain curves of the TPVs while it was hardly to obverse in that of EPDM vulcanizate during the uniaxial loading-unloading cycles. The maximum compression stress and internal friction loss at specific strain were decreased after the first loading-unloading while only decreased slightly at the later loading-unloading cycles; however, the residual deformation increased with the increasing of the cycle times of compression. Mullins effect could be significantly enhanced with increasing compression strain and HDPE content in TPV.