Films made from poly(vinyl alcohol-co-ethylene) and soluble biopolymers isolated from municipal biowaste

Blends were obtained from poly(vinyl alcohol-co-ethylene) and water-soluble biopolymers isolated from the alkaline hydrolysate of two materials sampled from an urban waste treatment plant: that is, an anaerobic fermentation digestate and a compost. The digestate biopolymers contained more lipophilic and aliphatic C and less acidic functional groups than the compost biopolymers. Evidence was obtained for a condensation reaction occurring between the biopolymers and the synthetic polymer. The thermal, rheological, and mechanical properties of the blends were studied. Films containing a low concentration (ca. 6-7%) of biopolymers exhibited up to three times higher yield strength than the neat synthetic polymer. The films' properties were found to be dependent on the concentration and nature of the biopolymers. The results offer a scope for investigating biopolymers sourced from other biowastes and for a better understanding of the reasons for the observed effects and exploiting their full potential for modifying or replacing synthetic polymers.