Surface characterization and properties of raw and degummed (Bombyx mori) silk fibroin fiber toward high performance applications of “Kisswa al-kabba

The purpose of this paper is the early evaluation of pre-treatment processes of Bombyx mori silk fibroin used to produce “Kisswa Al-Kabba” in order to determine the degree of efficiency and the differences among the most commonly-used degumming processes. Silk fibroin from the Bombyx mori silkworm was degummed through reproducibility processes in a customized method including natural soap degumming (tap water and deionized water) along with laboratory scale and factory scale machines. The results revealed that the maximum average value of sericin content was found to be 28.1669% (for tap water) and 28.5715% (for deionized water), indicating removal of all or most of the sericin. After neutral soap degumming, the initial modulus decreased from 108.7 gf/den to 55.1 gf/den, while the breaking tenacity decreased from 4.0270 gf/den to 2.7185 gf/den, indicating partial harmful damages of silk fibers molecules after neutral soap degumming method. These values decreased after degumming treatment, suggesting that the silk fibers become soft and stretchable. There was not much influence on elongation after degumming for different scale conditions. The tensile properties of the silk fibers after degumming laboratory scale machine (tap water) treatment was the worst. The degumming process or boiling process of silk fibers on a laboratory scale with tap water results in a serious decrease in the tensile properties. The surface morphology of the silk fiber shows that there was no important difference among the degumming approaches used in this study. The molecular conformation estimated by FT-IR stayed unchanged regardless of the degumming processes.