FRACTURE-TOUGHNESS INVESTIGATION OF THE DYNAMICALLY VULCANIZED EPDM PP/IONOMER TERNARY BLENDS USING THE J-INTEGRAL VIA THE LOCUS METHOD/

The fracture mechanics investigation of the dynamically vulcanized EPD M and PP/ionomer ternary blends was performed in terms of the J-integr al by measuring fracture energy via the locus method. The ternary blen ds consisting of EPDM, PP and ionomer were prepared in a laboratory in ternal mixer by blending and vulcanizing simultaneously. Vulcanization was performed with dicumyl peroxide (DCP) and the composition of EPDM and PP was fixed at 50/50 by weight. Two kinds of poly(ethylene-co-me thacrylic acid) (EMA) ionomers were used. The J-integral values at cra ck initiation, J(c), of the dynamically vulcanized EPDM and PP/EMA ion omer ternary blends were affected by the cation types (Na+ or Zn2+) an d contents (5-20 wt%) of the added EMA ionomers. The ternary blend con taining 20 wt % zinc-neutralized EMA ionomer and 1.0 p.h.r. DCP showed the highest J(c) values of the blends. The results have been discusse d with regard to the fracture topology observed by scanning electron m icroscopy (SEM).