Investigation on the thermomechanical properties of PLA/Lignin blends

Novel biobased polymer blend with wood like appearance was studied. The effect of lignin addition on a PLA polymer was investigated by varying the mixing temperature and the amount of lignin in the blend. The structure of the blend was unveiled combining fractionation techniques with size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) analysis. The blend showed tensile properties degradation after mixing at 190°C while the processing at 170°C showed less sever degradation. The degradation behavior was explained in terms of PLA degradation enhanced by the presence of the natural constituents in the blend. However, lignin showed also positive effects in terms of viscosity reduction during processing which allowed to lower processing temperature with clear benefits on the final blend performances.