Study on the microstructure and miscibility of dynamically vulcanized EPDM/PP blend by positron annihilation

Positron annihilation lifetime spectroscopy (PALS) was employed to investigate the relationship between the free volume hole properties and miscibility of dynamically vulcanized ethylene propylene diene monomer (EPDM)/polypropylene (PP) blend. The free volume hole concentration and the relative fractional free volume show negative deviation from linear additivity only when the weight percent of EPDM is over 50%. Combined with the results of dynamical mechanical thermal analysis measurements and mechanical properties tests, we found that the noncrystalline region of PP and EPDM are partially miscible and the miscibility of the blend became better when the weight percent of EPDM is over 50%. (C) 2003 Elsevier Science Ltd. All rights reserved.