The Research On The Degumming Methods Of Natural Bamboo Fiber

Natural bamboo fiber favored by people has excellent hygroscopicity, anti-bacterial and deodorant property, anti-ultraviolet function, environmental protection and other features. Bamboo grows rapidly, the yield is high, and the resource of bamboo is abundant in China. Applying bamboo resources to the textile industry has good prospect, and has positive effect in alleviating the pressure on the demand of wood and cotton. In this paper, the homemade crude bamboo fiber as research object, bamboo fiber was degummed by three methods, the degumming effect of different methods was explored, the best degumming method was chosen, and the structure and performance of natural bamboo fiber obtained were studied.Made hemicellulase and pectinase compounded in different proportions as a compound enzyme, bamboo fiber was treated with different degumming time, through the analysis of the weight loss percentage, the optical microscope, the strength, the influences of the proportion of compound enzyme and degumming time on degumming effect and fiber’s strength were investigated.The results showed, the degumming effect of compound enzyme was better than that of single enzyme, and with the increasing of the proportion of compound enzyme, the weight loss percentage rose from rapidly to slowly, then reduced gradually, and the weight loss percentage rose gradually with the extension of degumming time. And the optimum process conditions was:1.5 mg hemicellulase,2.0 mg pectinase, degumming time 2.5 h,38℃, pH value 5.2, and the weight loss percentage was 11.6%, the strength was 48.81cN with a low dispersion.Organic acid was used to degum the bamboo fiber in this paper, through the choice of catalyst and organic acid, discussing the impact of organic acid concentration, temperature, time on degumming effect. The results showed,0.3% HCl was more suitable for as catalyst to organic acid degumming than H2SO3 and HNO3, when the concentration was in 20%～80%, the degumming rate of formic acid was higher than that of acetic acid.The optimum condition obtained through orthogonal experiment was:80% formic acid,0.3% HCl,100℃, bath ratio of 1:25, degumming time 2h, and the biggest impact on degumming rate was the formic acid concentration, the next was the temperature, but the influence of degumming time to degumming rate was not significant. Under this condition, the degumming rate of bamboo fiber was 42.80%, no damage to the cellulose virtually.This paper mainly discussed the method of steam explosion and alkali boiling united degumming. To achieve better degumming effect, before treated by NaOH, bamboo fiber was presoaked and treated using steam explosion device. The single factor experiment analyzed the influence of the four factors, the steam explosion pressure, the keeping pressure time, the alkali concentration, the alkali treating time, on the degumming effect. In the experiment range of that, the pressure was in 0.4～1.0MPa, the keeping time was in 5-20min, the alkali concentration was in 2-4g/L, the alkali treating time was in 30～120min, the effect of united degumming was better than that of single alkali boiling or steam explosion treated, and the degumming rate increased with the increasing of steam explosion pressure, the pressure holding time, the concentration of NaOH, the alkali treated time, fiber was more decentralized,but overlarge explosion pressure and keeping pressure time would make fiber be burned. The best paramenters were:explosion pressure 0.8 MPa, keeping pressure time 20 min,4 g/L NaOH, alkali treated time 90 min, the hemicelluloses, lignin content of the fiber decreased by 41.61%,31.94%, respectively, the cellulose content rose to 63.59%.Through the orthogonal experiment, the conditions of the united degumming were optimized, the structure and performance of fiber were analyzed.The orthogonal experiment result showed that the steam explosion pressure, keeping pressure time and the alkali concentration were the important factor to the degumming effect, the greatest impact on degumming effect was the alkali concentration, the next was the steam explosion pressure,but the alkali treated time had no significant effect on the degumming effect. And the optimum process conditions obtained were: explosion pressure 0.9 MPa, keeping pressure time 20 min,4 g/L NaOH, alkali treated time 70 min, under this condition, the cellulose content rose from 40.51% to 70.54%, rose by 74.13%,the content of lignin, hemicelluloses, pectin decreased to 14.66%,13.98%,0.82%, decreased by 40.65%,55.32%,76.57%, respectively. The structure of the obtained fiber was investigated by FT-IR, WAXD, SEM, the result showed, the glue of bamboo fiber was removal of a certain degree after united degumming, fiber surface became more smooth, the diameter was down significantly, and there were still part of colloid residue on the fiber surface to make single bamboo fibers be sticked together, and formed longer fiber. The crystallinity of bamboo fiber increased, but did not destroy the cellulose, it was still the structure of cellulose I,and fiber was scattered. The dyeing rate, moisture absorption, strength of bamboo fiber were tested, compared to the fiber after single alkali boiling, the dyeing rate of fiber after united degumming was improved significantly, rose from 53.89% to76.22%, the moisture absorption has also been enhanced, the moisture regain under moisture sorption equilibrium rose to 14.77%, the moisture regain under moisture desorption equilibrium rose to 16.74%, the moisture absorption and liberation rates were higher than cotton and bamboo pulp fiber. The linear density of obtained bamboo fiber was 2.15 tex, the breaking strength and elongation were 23.83 cN and 3.25% (close to the jute process fiber), and the fiber production rate was 75.68%, could be used for the preliminary textile processing.