Properties of cellulose–soy protein blend biofibers regenerated from an amine/salt solvent system

Blend biofibers with relatively high protein content were fabricated from cellulose and soy protein isolate (SPI) using an ethylenediamine–potassium thiocyanate solvent system. Due to the decrease in solution viscosity, the SPI loading was limited to a maximum of 40 %, considering the 100 % draw down ratio applied during fiber coagulation. The results obtained from chemical and X-ray analyses support the formation of interaction through mainly secondary bonding. Increasing the protein content resulted in fibers with slightly improved thermal stability. Electron microscopy images of the fibers revealed a homogeneous dispersion of protein without clear phase separation. The percent crystallinity and the tensile data revealed that the best compatibility was obtained for 20 % SPI ratio and that the fiber exhibited the same birefringence as control fiber. In addition, blending cellulose with protein resulted in fibers with faster biodegradation.