Soy Protein Isolate Based Films: Influence of Sodium Dodecyl Sulfate and Polycaprolactone-triol on Their Properties

Summary: We report on the preparation and properties of soy protein isolate (SPI)-sodium dodecyl sulfate (SDS)-polycaprolactone-triol (PCL-T) films obtained by solvent casting from solutions containing variable amounts of SDS or SDS/PCL-T. It is shown that the mechanical and thermal properties, and the morphology of SPI-based biofilms can be easily controlled by changing SDS, PCL-T, and moisture contents, enabling the fabrication of rigid and flexible materials as pure SPI films Young's modulus ～ 1 400 MPa, elongation at break (E) ～ 2%, and glass transition temperature (T_g) ～ 150 °C] and SPI/SDS/PCL-T films with PCL-T] ≥ 18% (Young's modulus ～ 50 MPa, E ～ 90%, and T_g ～ 135 °C), respectively. Micrographs taken at the cross-section of biofilms whose PCL-T] ≥ 18% revealed the occurrence of a porous matrix, whereas a dense bulk phase was otherwise observed (pure SPI, SPI/SDS, and SPI/SDS/PCL-T films with PCL-T] < 18%).