a new approach to environmentally friendly protein plastics and foams

New formaldehyde-free and isocyanate-free bioplastics and biofoams were prepared by reacting ovoalbumin and dimethyl carbonate (DMC) at a moderate temperature. Analysis by 13C NMR revealed a reaction between dimethyl carbonate and the amino and/or hydroxyl groups of the side chain of amino acids. The densities were between 0.6 and 1.1 g/cm3 for the obtained plastics. Thermal and mechanical resistances peaked at 175 °C and 7.7 MPa, respectively. The Brinell hardness was 2. The prepared foam exhibited a density of 0.1 g/cm3 and an open cell structure. Impregnation with hexamethylene diamine (DAH) allowed for the preparation of materials with elastic mechanical behavior through the reaction of DAH and DMC. The new plastics and foams derived from ovoalbumin protein were markedly more environmentally friendly.