Degumming Technology Of Cotton Stalk Bast Fibers And Its Analysis Of Degumming Effect

In recent years, people pay more and more attention on natural fibers, especially the fibers taken from agricultural waste. China has large areas of cotton which is one of the major raw materials of human clothes. Cotton stalk bast is agricultural waste material after cotton’s being taken, so the number of cotton stalk bast is quite considerable every year, if taking measures to develop and utilize it to be a raw material of spinning, it not only can meet the needs of the development of textile industry, and reduce the pressure caused by price increase on cotton recently, but also can reduce environmental pollution and turn waste into treasure.Cotton stalk bast fibers are extracted from cotton stalk bast, and first step to develop cotton stalk bast resources is to extract soft and thin fibers. Cotton stalk bark fiber is a kind of bast fiber whose main components are cellulose, hemicellulose, lignin, fat waxy, pectin, water soluble content, ash content, of which content of hemicellulose, pectin and lignin is relatively higher, These non-cellulose materials make the single fibers of cotton stalk bast bonding together, which make cotton stalk bast fibers thick and hard, poor spinnability. So degumming is the method to extract cotton stalk bast fibers. The cotton stalk bast fibers after degummed will have great developing potential and wide market prospect.This paper mainly completed determination of the chemical composition of the cotton stalk bast, pretreatment before degumming and three different methods of degumming. Chemical composition was determined according to "ramie quantitative analysis method of chemical composition". Two pretreatment methods were discussed in the degumming pretreatment which were pre-oxygen treatment and pre-ultrasonic treatment, through contrast we screened that pre-oxygen treatment was a suitable treatment for cotton stalk bast fibers, which laid foundation for the next degumming process. In degumming experiment, three degumming methods were used which were high temperature degumming, compound enzyme degumming and high temperature-enzyme degumming.In high temperature degumming method, orthogonal experiment was used to detect the effect of sodium hydroxide concentration, temperature, time and liquor ratio on content of lignin, residual gum content, fineness and breaking strength. After that binary quadratic regressive orthogonal experiment was done according to the most effective two factors in the orthogonal experiment, residual gum content and breaking strength were used to judge whether the degumming effect was fine. The final optimal process was:temperature131℃,sodium hydroxide concentration11.26%,temperature holding time50min,liquor ratio1:20.Under this process we detected that lignin content at5.82%,residual gum content at6.03%,fineness at2.93tex,breaking strength between6.5～7cN-dtex-1, principal length between70～90mm. Every target of the fibers through post-treatment was improved so that the degumming effect was better. In the compound enzymes degumming, single factor analysis was first used to detect the effect of compound enzyme proportion, compound enzyme content, time, temperature and pH on content of residual gum content, fineness and breaking strength, then taking compound enzyme content, time, and temperature as detected targets, residual gum content, fineness and breaking strength as tested targets, ternary quadratic orthogonal regressive experiment was made to optimize the conditions of the compound enzyme treatment. The results showed when concentration of compound enzymes was1.97%, degumming time was24.8h and temperature was49℃, the cotton stalk bast fibers were tested, of which lignin content was6.04%,the residual gum content was6.21%, fineness was1.78tex, breaking strength was between8～8.5cN-dtex-1, principal length was between80～100mm,each target of the fibers was relatively improved. Cotton stalk bast fibers were prepared through high temperature-enzyme degumming, of which lignin content was3.83%,residual gum content was2.31%,fineness was1.74tex、breaking strength between5^6cN·dtex-1,principal length between55～65mm. Through comprehensive comparision, content of lignin and residual gum by high temperature-enzyme degumming was the lowest and every other target also met spinning demand, which was the optimal degumming process. Besides, considering of demands of energy consumption and environmental protection, compound enzymes degumming showed its own advantages and the fibers also met the demand of spinning, which could be made as an alternative method.