Investigation of the effects of environmentally friendly degumming methods on silk dyeing performance

In this paper, firstly the effects of environmentally friendly degumming methods on the morphology and structure of fibers have been investigated. Then the dyeing behaviors of environmentally friendly degummed silk fibers were analyzed. In the dyeing process, acid and reactive dyes were used at various dye concentrations. To analyze dyeing characteristics of these fibers, investigations of washing fastness and measurements of color parameters were carried out. Scanning electron microscopy (SEM) images of degummed silk fibers showed that the high temperature (HT) degumming method was more successful than the other methods, but the results were comparable. Weight loss values were also supported by SEM images. Scanning electron microscopy with energy-dispersive X-ray analysis of degummed fibers showed that particles remaining on the surface were the most likely to indicate sericin residue. Fourier transform infrared spectra of raw and degummed fibers with different methods demonstrated typical absorption bands appointed to the peptide bonds (-CONH-) and no major differences were observed. When band intensity was examined, the most intense bands belong to the HT degumming process. The differential scanning calorimetry curves of conventionally and alternatively degummed silk fibers showed two endotherms at around 100℃ and 320℃ because of water loss and β-sheet fibroin decomposition, respectively. The acid and reactive dyeing of the degummed fibers by environmentally degumming methods gave similar color strength and washing fastness values compared with conventionally degummed fibers.