Abstract: Hyperbranched polyester (HBPE) was synthesized through a “one-step” process by using 2,2dimethylol propionic acid and trimethylolpropane as raw materials and ptoluene sulfonic acid as a catalysts. The epoxyterminated HBPE with three generations (EHBP-G3) was prepared through the modification of HBPE with epichlorohydrin. The poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)/EHBP blends were prepared through a melt processing method and then characterized by differential scanning calorimetry (DSC), polarizing microscopy, and mechanical and rheological evaluations. The results indicated that the degree of crystallinity of PHBV decreased by 16.1 % with addition of 1.5 wt% of EHBP-G3, and meanwhile, its impact strength increased by 34.28 %. The reduction in crystallinity may lead to an improvement in impact toughness for PHBV/EHBP blends.

Key words: hyperbranched polyester, poly(hydroxybutyrate-co-hydroxyvalerate), blending, modification