Influence of extrusion processing on blends of poly(butylene succinate) and plasticized soy protein isolate

Processing parameters such as extrusion screw rotation and cooling were analyzed in this research with blends of plasticized soy protein Isolate (PSPI) and poly(butylene succinate) (PBS). The goal was to develop more efficient ways of processing soy protein based bioplastics in standardized equipment so that they can be utilized to their full potential when processed on a large scale. The study was divided into two parts: (1) Analyzing extrusion processing's counter-rotation (CTR) and co-rotation (CR) blending techniques and determining which allowed for enhanced destructurization and mixing of the two materials; (2) Understanding how soy protein and biopolymer based films respond to slow (air) and fast (water) cooling techniques using DSM micro-compound extrusion and compression film processing (CFP).;Overall, CTR extrusion provided enhanced interfacial adhesion, tensile elongation (∼40% higher for PSPI-CTR material & -55% higher for PBS: PSPI-CTR (70:30) blends) and prolonged onset (Tonset) and end (T end) thermal degradation temperatures (CTR blend ∼10°C > CR blends). The second studied demonstrated that the slowly cooled nature of the DSM films (∼30C/min) showed higher percent crystallinity and storage modulus for both CTR and CR processed blends, compared to their CFP (fast cooling) counterparts. The tensile strain for the DSM film was also 9.9% higher than those of the CPF counterpart.