Effects of reprocessing on the structure and mechanical properties of poly(trimethylene terephthalate)

The effects of reprocessing by extrusion for up to four cycles on the structure and mechanical properties of poly(trimethylene terephthalate) (PTT) were studied. Reprocessing did not change the chemical structure of the polymer but led to both yellowing and molecular weight reduction. Young's modulus and the yield stress of PTT remained constant or decreased with successive extrusion cycles, probably because of the observed slight specific volume increase. The continuous reduction in the break properties due to reprocessing was smaller than that found in similar polyesters and was attributed to the molecular weight reduction.