Male Silk Properties and Comparative Study of Its Optimal Dyeing Conditions When Dyed with Reactive and Acid Dyes
|Author||Lodrick Makokha Wangatia|
|Keywords||Silk fibers Reactive dyes dyeing Dyeing Fixing Fiber test instruments Color fastness fibroin Staining than Acid dye Argus Dyeing effect dyeability Leveler Fourier transform infrared spectroscopy Degumming process higher value Breaking strength Initial modulus|
Silk has been used as a textile fiber for more than 5000 years, it has got outstanding properties as natural fiber which are not found in all other fibers. Man made fibers like nylon have been developed to match silk but still, silk remains to withstand there competition. Recent fashion trends have switched to natural scene resulting to increase in demand for silk products. This has attracted more research on silk and one of the latest outcomes is a new silk grade has been developed by gender separation. Silk cocoons have been separated into male and female using UV light, the male cocoon have produced silk filament of better quality compared to normal silk (not separated). Development of new silk variety mostly involves alteration of some physical and chemical properties of the filaments which in the long run changes the silk filament dyeing properties. These changes make it difficult to dye the new varieties with the same conditions given by the manufacturer or commonly used to dye ordinary silk to achieve the same results. The aim of this thesis was to highlight male silk properties, optimize the dyeing conditions of male silk using reactive and acid dyes and compare the two types of dyes to see which one is most suitable to use.In order to achieve the stated aims the thesis has been divided into seven chapters. Chapter one deals with literature review, the source of silk has been explained including its structure and chemical composition so as to understand how it is expected to react in different conditions. Previous research work to improve the silk properties using various methods which includes:fibers modification by change of food fed on the silk worm, genetic modification, modification of fiber during processing and finishing has been explored. Since the thesis is about dyeing silk with reactive dyes and acid dyes, an overview of the two dyes has been given. The theory of the statistical tools used in the thesis have been explained, some of the tools include how to test for normality, test of significant difference etc.In chapter two the thesis deals with research methodology where experimental procedure for all the experiments and test done have been explained. The silk degumming process has been outlined, instruments used to test the fiber properties explained, dyeing procedure used for reactive and acid dyes including flow charts have been given plus names of all the chemical reagents and dyes used. In chapter three the male silk properties have been covered. Different fiber testing instruments have been used to test both the physical and chemical properties. The scanning microscope shows that male silk are finer, compact and have small size pores on its cross section compared to normal silk. FT-IR spectras shows that male silk has similar chemical composition like normal, no stretching or bending band have disappeared or have been introduced in the male silk spectra but shift in main band is observed showing reduction of NH groups, also OH band have broadened. Degumming process transforms the Male silk molecular structure of Amide I and AmideⅡfromα-conformation to (β-conformation. X-ray diffraction curve and thermo gravimetric analyzer shows that crystallinity, breaking strength and initial module of Male silk are higher than the ordinary silk while crystal structure is the same. Heat stability of male silk is better than that of normal silk. The moisture regain rate of normal silk changed faster than that of male silk,9.1% and 8.5% respectively.In chapter four the thesis deals with dyeing of male silk fiber with reactive dyes, red and yellow color reactive dyes from two different companies have been used. The exhaustion of reactive dyes to male silk is found to be lower than the normal silk. Male silk improves adsorption when exhaustion salt and temperature are increased. There was no higher requirement of fixation agent and the time required for fixation was found to be less than that of normal silk, the color fastness property is found to be as good as normal silk. Male silk has lower K/S value when compared to normal silk at same dye concentration and all other factors are kept constant.In chapter five acid dyes have been dealt with, the dyes were supplied by two companies, Everlight and Dystar companies. The acid dyes had very high exhaustion on male silk dyes but the K/S value showed significant difference when compared with normal silk dyed with same conditions. Change of procedure where dyeing is first done, then leveling agent is added later improves the K/S of male silk. Dystar dyes worked well at lower temperature and Everlight dyes needed higher temperature. The amount of leveling agent and time was similar to normal silk.Chapter six deals with optimal conditions favorable for dyeing male silk with reactive and acid dyes, normal silk and male silk were also dyed according to manufacturers’procedure. The K/S, lightness and hue values were compared. Male silk dyed with optimal conditions results were better than the male silk dyed like normal silk. In some cases the male silk optimally dyed is better than the normal silk. Dystar acid was found to be the best dyes to use on male silk since its adjustment requirement were very minimal and had little effect on cost, but when color fastness properties are required then reactive dyes must be used.The last chapter deals with summary of the results found in the thesis and briefly discuss the limitation of this research work. The thesis only dealt with the male silk and used normal silk for comparison since it was not possible to get female silk supplied by the contact company. There is need to research also on female silk so that more insights can be derived. The molecular weight of the dyes used was not available, there is a general feeling that the male silk respond well on dyes with smaller dye particle, this needs to be ascertained.