Poly(epsilon-caprolactone-co-D,L-lactide)/silk fibroin composite materials: Preparation and characterization

Poly(epsilon -caprolactone-co-D,L-lactide) copolymers with 10, 30, and 50% by weight of silk particles (size range: 5-250 mum) derived from Bombyx mor i were blended in acetone solution. After evaporation of the solvent, the m orphology, thermal behavior, and mechanical properties of the composites we re examined. The composites were transparent and the silk fibroin particles were homogeneously distributed within the composite structure. The particl es appeared as bright reflected images under the optical microscope, sugges ting that they were in a crystalline state. DSC thermograms of the composit es revealed that the glass transition of the matrix was at ca. -18 degreesC . Degradation of the silk fibroin occurred beyond 270 degreesC. The decompo sition temperatures and degradation rate decreased with increasing silk fib roin content as revealed by TGA analysis. FTIR spectra of the composites sh owed absorption bands at 1730 and 1088 cm(-1) for the copolymer and at 3273 and 1617 cm(-1) for the silk fibroin. Although the characteristic lines of poly(epsilon -caprolactone-co-D,L-lactide) were independent of filler conc entration, the absorption bands of the beta -sheet form of the silk fibroin increased slightly due to the interaction of silk fibroin with the copolym er.