Compound Finishing of Bombyx mori Silk: A Study of Cold Oxygen Plasma/Titania Sols Treatments and Their Influences on Fiber Structure and Performance

Abstract

Degummed Bombyx mori (B. mori) silk fabrics modified by cold oxygen plasma (COP) and/or titania sols (TSs) were investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction, field emission scan electronic microscopy (FE-SEM), thermo-gravimetric and differential thermal analysis, and ultraviolet (UV) transmittance methods in this study. FT-IR analysis demonstrated that titania particles were associated with B. mori silk fibers by forming organic–inorganic hybrid blends. Processing sequences of COP and TSs, and curing conditions showed significant impacts on the crystalline, thermal, micro-morphological, and UV resistant characteristics of silk fabrics. Crystallinity index by both area and height methods, and crystallite sizes of silk fabrics were calculated as well. Results showed that crystallinity index of finished samples approximate to that of degummed silk fabric could be obtained by applying TSs and curing at 160 °C for 2 min prior to COP treatment, or vice versa with lower temperature of 140 °C for 3 min, whereas the crystallite sizes of treated samples increased slightly. The initial decomposition temperatures of finished samples were elevated by 23–35 °C with increased char residues at 600 °C, while the transmittance of UVA and UVB of finished samples decreased by 11.7, 17.7%, respectively. FE-SEM analysis revealed that titania particles were associated on the fiber surfaces with different smoothness.