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

Abstract

AbstractSummary: 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 (Tg) ∼ 150 °C] and SPI/SDS/PCL‐T films with [PCL‐T] ≥ 18% (Young's modulus ∼ 50 MPa, E ∼ 90%, and Tg ∼ 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%).