Maleinated polyflavonoids and lignin as functional additives for three kinds of thermoplastics

Polylactic acid (PLA)-, polystyrene (PS)-, and polyethylene (PE)-based blends were prepared with Pinus radiata modified/unmodified polyflavonoids and lignin. The modified polyphenols were esterified with maleic anhydride at 20 °C for 24 h to diversify the application potential of the resulting blends. The rheological, morphological, thermal, and mechanical properties of the blends were studied. The type and amount of polyphenols affected the torque values and the time of mixing, as well as thermoplastic chemical structure of the blends. Lignin showed the best miscibility features, while polyflavonoids were less miscible in PE. An increase in the polyphenol amount in the blends led to a decrease in the decomposition temperature ( T d ) in PLA-based blends. A marginal influence of the polyphenols on the T d values of PS- and PE-based blends was observed, as well. The flexural features were significantly affected by the additive content. An increase in the polyflavonoids load increased the elasticity modulus ( E ) of the PS- and PLA-based blends. In contrast, unmodified lignin increased the E values of the polymers except PE. Bark polyflavonoids and lignin from radiata pine might be used for the design of thermoplastic blends. The polymer morphology as well as the functional group composition are the key factors to understand the compatibility/miscibility features of the blend components.