Biobased polymer blends of poly(trimethylene terephthalate) and high density polyethylene

Abstract

Two biobased polymers, poly(trimethylene terephthalate) (PTT) and high density polyethylene with varying concentrations were injection molded for their performance evaluation. Differential scanning calorimetry determined that the majority of the blends exhibited a cold crystallization peak in the first heating cycle. Dynamic mechanical analysis revealed an increase in the storage modulus after the material has passed its Tg which can be related to the material's ability to cold crystallization. Blending demonstrated intermediate values for the tensile and flexural properties in comparison to each neat polymer. However, the notched Izod impact strength was higher for blends containing less than 50wt.% biobased polyethylene (BioPE) compared to the virgin materials. The best performance in comparison to the other blends was observed for the PTT/BioPE (80/20) wt.% formulation, which had balanced tensile and flexural properties and an increase of 64% in the impact strength. This was explained through the impact fracture morphology via scanning electron microscopy. Variations in PTT and BioPE loading resulted in different surface structures, phase distributions and particle sizes. PTT as the minor phase resulted in randomly distributed large spheres. Whereas, when BioPE was the minor phase, it formed small uniform spherical/rod-like structures. Smaller particle size provided a toughening effect on the impact strength.