Crystallization behavior of poly(ethylene terephthalate) blended with hyperbranched polymers: The effect of terminal groups and composition of hyperbranched polymers

The effects of terminal groups and composition of hyperbranched polymers (H BPs) on the crystallization behavior of poly(ethylene terephthalate) (PET) in HBP/PET blends were investigated using in situ FT-IR spectroscopy and di fferential scanning calorimetry. Hyperbranched aliphatic polyester was synt hesized from an AB(2) type monomer and a B-3 type core. The hydroxyl termin al groups of the HBP were transformed into acetate and benzoate groups by o rganic synthetic methods. The effects of the HBPs were compared with those of linear polyester (LPE) synthesized from an AB type monomer and a Bz type core. A small amount of HBP with hydroxyl groups could greatly reduce the relative crystallinity of PET through hydrogen bonds. HBP with acetate grou ps showed effects similar to those of LPE. As the composition of LPE was in creased, the relative crystallinity of PET was slightly decreased. On the c ontrary, HBP with benzoate groups played the role of nucleating agent in th e blends with PET. The crystallization rate of PET was highest in the blend with 12 wt % HBP. Dynamic viscosity measurements were performed to investi gate the role of the HBPs as processing aids.