Effect of Degumming Duration on the Behavior of Waste Filature Silk-Reinforced Wheat Gluten Composite for Sustainable Applications

Abstract

Silkworm silk proteins are of great importance in several fields of science owing to their outstanding properties. India generates waste silk fibers, also known as waste filature silk, in abundance. Utilizing waste filature silk as reinforcement in biopolymers enhances its physiochemical properties. However, the hydrophilic sericin layer on the surface of the fibers makes it very difficult to have proper fiber–matrix adhesion. Thus, degumming the fiber surface allows better control of the fiber properties. The present study uses filature silk (Bombyx mori) as fiber reinforcement to prepare wheat gluten-based natural composites for low-strength green applications. The fibers were degummed in sodium hydroxide (NaOH) solution from a 0 to 12 h duration, and composites were prepared from them. The analysis exhibited optimized fiber treatment duration and its effect on the composite properties. The traces of the sericin layer were found before 6 h of fiber treatment, which interrupted homogeneous fiber–matrix adhesion in the composite. The X-ray diffraction study showed enhanced crystallinity of the degummed fibers. The FTIR study of the prepared composites with degummed fibers showed that shifted peaks toward lower wavenumbers supported better bonding among the constituents. Similarly, the tensile and impact strength of the composite made of 6 h of degummed fibers showed better mechanical properties than others. The same can be validated with the SEM analysis and TGA as well. This study also showed that prolonged exposure to alkali solution reduces the fiber properties, thus reducing composite properties too. As a green alternative, the prepared composite sheets can potentially be applied in manufacturing seedling trays and one-time nursery pots.