Toughening of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) by phenyl terminated hyperbranched polyesters with higher thermal stability

Abstract

AbstractPhenyl terminated hyperbranched polyesters (HBP‐Bs) were synthesized based on Boltorn‐type hydroxyl terminated HBPEs and characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, and so forth. The prepared HBP‐Bs were used to toughen poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) directly by melt blending. The thermal properties, rheological properties, mechanical properties, and microstructure of the PHBV/HBP‐Bs blends were studied in detail. Comparing with pure PHBV, the crystallinity of the PHBV/0.5 phr HBP‐Bs blends decreased by 14.10% (from 64.39% to 55.04%), the impact strength increased by 158.30% (from 7.41 kJ·m−2 to 19.14 kJ·m−2), and the elongation at break increased by 400.00% (from 0.91% to 4.55%). It can be seen from the scanning electron microscope that the fracture surface of the PHBV/HBP‐Bs blends became rough with the increase of HBP‐Bs, even with large filamentous structures and tiny holes, which further demonstrated that HBP‐Bs acted as an excellent toughening effect on PHBV.