Investigation on Structure and Thermomechanical Processing of Biobased Polymer Blends

The structure and composition of a biobased polymer blend with wood like appearance was studied. The effects of processing time for mixing at 190 °C was investigated. The structure of the blend was unveiled combining fractionation techniques with size exclusion chromatography and nuclear magnetic resonance analysis. The material was found to be a blend of polylactide (PLA) polymer with 15.4 wt% ground softwood and 5 wt% soda lignin. The findings about composition supported the explanation of the thermal behavior and the processing stability analysis. The blend showed tensile properties degradation after mixing at 190 °C for 25 min. The ultimate tensile strength dropped from 29.75 to 4.85 MPa while the tensile modulus dropped from 5.3 to 4.2 GPa. The degradation behavior was explained in terms of the PLA degradation enhanced by the presence of the natural constituents in the blend.