Formation Of Microvoids In Bombyx Mori Silk And Its Filling Properties

This dissertation expanded on the formation and characterization of microvoids in B. mori silk fibers, as well as filling properties and feasibility of modified B. mori silk fibers. Structure and properties of modified B. mori silk fibers by physical and chemical methods are separately studied in this paper. CaCl2-EtOH-H2O solution is always used to dissolve B. mori silk fibroin to get peptide in the silk industry, and here it is used to modify B. mori silk by partly dissolved treatment. Medium calcium salt of calcium nitrate is also used to modify B. mori silk. The similarities and differences of B. mori silk fibers treated by above two kinds of calcium salts are studied. The results show that the weight of B. mori silk fiber becomes light and slight longitudinal erosive stripes appear on silk fibers after calcium treatment. At the beginning of calcium salt treatment, B. mori silk fibers swell and disperse, crystallinity of calcium treated silk fibers increased, and conformation of silk fiber has the trend of βsheet. Calcium nitrate solution penetrates B.mori silk fibers quickly while calcium chloride aqueous solution does quickly. B.mori silk fibers shrink evidently after calcium nitrate solution while shrink little in calcium chloride solution. B.mori silk fibers swell and dissolve simultaneously when treat in the calcium solution. Low-temperature oxygen plasma is also applied to modify B.mori silk fibers. The weight also decreases with increasing plasma treatment time because of erosion and oxidation. Eroded stripes and micropits are found on the surface of plasma treated fibers. Meanwhile, surface of treated fibers becomes coarser. Not only surface morphology but also the inner conformation changes after oxygen plasma treatment. Oxidation and reduction caused by oxygen plasma made silk fibroin macromolecules reorganize and inner conformation of silk fibers change from random coil to βsheet. Crystallinity of plasma treated silk fibers changes little for short-time treatment, while decreases gradually with treatment time for long-time treatment. Endothermic decomposition temperature also decreases after long-time plasma treatment. Stannic chloride is used to characterize the microvoids in modified silk fibers by tin weighting process. Tin weight gain of calcium nitrate solution modified silk is bigger than that of ordinary B. mori silk, and it increases with increasing calcium nitrate treatment time. Tin weight gain of CaCl2-EtOH-H2O treated fibers also improves. Tin weight gain of oxygen plasma treated B. mori fibers increases with increasing treatment time and it is the positive correlation between them. The weighting properties of silk fibers modified by both CaCl2-EtOH-H2O and plasma are also studied and the weight gain of it is much higher than that of both CaCl2-EtOH-H2O treated fibers and oxygen plasma treated fibers. It indicates that combining two kinds of treatment methods can improve the microvoids in silk. Ore powder and negative ions finishing agent solution are used to treat ordinary silk fibers and calcium modified silk fibers in the last part of dissertation. And the weight gain of modified silk fibers is much higher than that of ordinary silk fibers, meanwhile adhensive materials on the surface of modified silk fibers are much less than that of ordinary B. mori silk fibers. It proves that microvoids are formed in the B.mori silk by calcium modification, and make it easy for superfine powder to fill into the silk fibers.