A starch based sustainable tough hyperbranched epoxy thermoset

With the growing concern of long term environmental and waste management problems, the recent trend in the polymer industry is aimed to utilize environmentally benign substrates for development of sustainable polymers with the required properties for their potential applications as substitutes for petrochemical derivatives. In this arena, the authors aspired to use starch, a natural renewable polysaccharide obtained from a wide variety of crops, as one of the reactants for a one-pot synthesis of a bio-based sustainable hyperbranched epoxy resin. Nuclear magnetic resonance (H-1 NMR and C-13 NMR), Fourier transformed infrared spectroscopy (FTIR) along with different analytical techniques confirmed the chemical structure of the resin. The poly(amido amine) cured epoxy thermoset exhibited acceptable biodegradation along with desirable properties. It exhibits excellent impact resistance (>100 cm), outstanding scratch hardness (>10 kg), exceptionally high tensile adhesive strength (up to 2906 MPa for aluminum), moderate tensile strength (up to 29 MPa), good elongation at break (up to 38%), high toughness (up to 8.40 MJ m(-3)) and very good chemical resistance against a number of chemical environments. Moreover, the thermoset displayed potent biomedical attributes by exhibiting cytocompatibility with erythrocytes as assessed through a hemolytic assay. Thus, the synthesized eco-friendly and sustainable hyperbranched epoxy thermoset with good toughness and exceptional adhesive strength can be a worthy replacement for petroleum-based epoxy thermosets as an advanced engineering material.