Epoxy modified bio-based hyperbranched polyurethane thermosets

Abstract

Modification of the existing polymers leads to improvement of many desirable properties. Hence, prepared hyperbranched polyurethane was modified with different amounts of bisphenol-A based epoxy resin. The modified system was cured by cycloaliphatic amine hardener at 120 °C for a specified period of time. The curing reaction was confirmed by Fourier transform infrared spectroscopy and swelling study. The tensile strength (5.5–16 MPa), scratch hardness (3–10 kg) and gloss (85°–94°) increased with the increase of epoxy content. The thermo-gravimetric analysis showed the enhancement of thermal stability (240–291 °C) of the modified systems. Biodegradation was tested by the broth culture technique and the modified hyperbranched polyurethanes also exhibited adequate biodegradation. Incorporation of reactive modifier into the polyurethane network was demonstrated to be an effective way to improve the thermal and mechanical properties, simultaneously.