Wet-spun blend biofibers of cellulose–silk fibroin and cellulose–chitin–silk fibroin

Each spinning solution of silk fibroin–sodium cellulose xanthate (viscose) in aqueous NaOH, and silk fibroin–viscose–sodium N-acetylchitosan salt (alkaline chitin) in aqueous NaOH was spun at room temperature through a spinneret (0.1 mm in hole diameter) into a 10% aqueous sulfuric acid solution containing 40–43% ammonium sulfate. Novel white blend biofilaments were obtained in over 95% yield. The cellulose–silk fibroin filaments containing less than 10% silk fibroin had 4.9–9.9 denier for the titer value, 1.08–1.20 g/denier for the tenacity value and 29.7–35.0% for the elongation value. The cellulose–chitin–silk fibroin filaments containing less than 43% silk fibroin had 3.9–5.0 denier for the titer value, 0.70–0.93 g/denier for the tenacity value and 20.6–28.6% for the elongation value.