Study On High Temperature And High Pressure Degumming Process With Ligninase Of Hemp Fibers

Hemp has unique feature and performance, such as antibacterial and healthprotecting, breathable moisture absorption, noise absorption, protection againstUV radiation, anti-static electricity and biodegradable. It is a kind of "greenfiber" which is very eco-friendly, widely applied in the future. Hemp textiles isthe green functional products which has bright development prospects in the21st century. But the hemp fiber contains hemicellulose, lignin, pectin and wax,and these noncellulosic substances have an influence on the spinning, dyeing,and finishing of yarns and fabrics. It is important to remove the most ofnoncellulosic components, namely degumming, in order to make good use ofhemp fiber. Therefore, the key of the textile field research is hemp degummingprocess research.Traditional hemp degumming processes have natural water retting,mechanical degumming and chemical degumming methods, natural waterretting has many disadvantages such as long process time, low efficiency,heavy laboring intensity and the quality is unstable. Mechanical degummingcommonly used as a pretreatment. Chemical degumming need to use a largeamounts of chemical reagents and water, high cost and lead to pollute environmental. The performance and spinnability process of hemp can besignificantly improved by finding a way that almost no pollution to theenvironment, less consumption and high cost performance. Therefore, based onthe flaws of the hemp, we are researched a new degumming technology whichcan develop moderately degumming and reduce the dosage of chemical reagentto protect the environment. The experiment made from several aspects:1. We project a hemp pretreatment process: first of all we use the ultrasonicboiled and pre-acid to deal with hemp; Then use UV-radiation and freeze-heat todegum hemp;2. Last we use high temperature and high pressure degumming process withligninase treatment of hemp fiber;3. The optimum parameters of HTHP degumming process with ligninasetreatment of hemp fiber were obtained and research influence of these optimumparameters on hemp residual gum content and breaking stress.Scanning electron microscopy (SEM), infrared (FTIR), thermogravimetric(TG) were used to characterize and analyze the chemical structure and surfacemorphology before and after hemp degumming. The results showed that:1. The optimum parameters of HTHP degumming process with ligninasetreatment of hemp fiber were obtained:(1) Ultrasonic boiled treatment was use100min, the temperature was70℃;(2) In acid treatment, the treat temperatureand time were50℃and90min and acid concentration was2.5g/L;(3) The UV-radiation time was20min, concentration of hydrogen peroxide and sodium hydroxide were6g/L;(4) The freeze-heat treat time were20min, freezingtemperature was minus55℃;(5) Ligninase treatment was2h, concentrationwas8g/L;(6) High temperature and high pressure processing use the0.15MP,temperature was127℃, reaction time was30min, concentration of H2O2andNaOH were8g/L.2. After degumming processing, residual gum content and lignin contentwere decreased dramatically, residual gum content decreased from43.12%to2.26%, and the lignin content reduced to0.71%from14.23%.3. Colloid of hemp surface almost all were removed, surface was smooth,white degree increased from16.4to76.3, fiber is fine and uniform, goodmechanical properties, Thermal stability was increased, the initialdecomposition temperature was improved from231℃to279℃.4. Dosage of chemical reagent was decreased by36%, and reduced toprotect environment.