Compatibilization of acrylic polymer-silk fibroin blend fibers: 2. Morphology and mechanical properties of the compatilized blend fibers

Three synthesized acrylonitrile-graft-silk fibroin copolymers (AN-g-SF), de noted as COP-65, COP-87, and COP-106, were used as potential compatilizers for acrylic polymer-silk, fibroin blend fibers. Due to their different mole cular weights and architecture, the compatibilizing efficiency is in the or der of COP-106 > COP-65 > COP-87. To maintain the "sheath-core" structure o f the blend fiber, COP-65 was chosen as the compatilizer. It was found that the addition of a small amount of COP-65 (up to 2 wt %) results in finer a nd more even distribution of the SF fibrils. On the contrary, excess COP-65 will cause flocculation and coalescence of the SF phase. Similarly, mechan ical properties are enhanced with an optimum amount of the compatilizers. H owever, when excess COP-65 is added, the mechanical properties of the blend fibers are even worse than that of the uncompatilized samples. The mechani sm of these findings is also discussed. (C) 1999 John Wiley & Sons, Inc.