Influence of compatibilization on the mechanical behavior of poly(trimethylene terephthalate)/poly(ethylene–octene) blends

Poly(trimethylene terephthalate) (PTT) based blends toughened with up to 30 wt.% of a partially maleinized poly(ethylene–octene) copolymer (mPEO) were obtained by melt mixing. The blends were composed of two pure amorphous phases and a partially crystalline PEO phase. The rubber modification clearly compatibilized the blends leading to a decrease in the dispersed phase size. The decrease was not enough to attain the brittle–tough transition, but an increase in the shear rate gave rise to an additional decrease in the dispersed phase size and in the interparticle distance (IDc) that led to very high toughness values (15-fold the notched impact strength of the matrix) at rubber contents above 25 wt.%. The critical interparticle distance of the blends was 0.17 μm. A comparison between this IDc and those of PBT/mPEO and PET/mPEO blends was explained in terms of their interfacial tensions.