Study On Alkali-H₂O₂-Whisk Degumming Technics With Freeze-Heat Treatment And UV-Radiation Of Hemp Fibers

Hemp fibers have many natural healthcare functions,such as good bacterial repellency and inhibition,good absorption-air-permeability,shielding radiation. At the same time,hemp fiber is emollient,frash and comfortable.What is more, hemp has the ecology-safe-productivity and end-product-recycling.It is the real "green product".So many experts believe that hemp is a kind of ideal textile fibers and most prospective cellulosic fibers in the future.However,hemp fibers consist of both cellulosic and noncellulosic substances,such as hemicellulose,lignin,pectin and wax,and these noncellulosic substances have an influence on the spinning,weaving,dyeing, and finishing of yarns and fabrics.In order to make good use of hemp fibers,it is important to remove the most of noncellulosic components,namely degumming.And it is also a key problem in the preliminary working.The difficult degumming is the characteristic of hemp fibers.To make a comprehensive view,there are some methods for the hemp dugumming.For example,the method of natural fermentation has many disadvantages such as long process time,much climatological dependence and having not much quality assurance,and so on.Chemical degumming,which is often used in industry at present,has the disadvantages of long process and time,high-cost and consumption,too.Though the biological and enzyme degummings have little energy consumption,they aren't complete and need second chemical treatment. The mechanical processing,explosive treatment,ultrasonic technics and alkali-H₂O₂ methods have some advantages such as saving time,protecting environment,improving fiber separability or degumming-bleaching simultaneously,but,they are in the stage of research now.To resolve the problems as mentioned above,the alkali-H₂O₂-whisk degumming technics were used with freeze-heat treatment and UV-radiation. The flaws and micro-holes of hemp fiber's surface will expand and spread while it is frozen,and the change will be reverse while it is heat.The opposite changes is beneficial to absorb easily chemical reagents,and the fiber's physical-chemical properties have apparently changed.The UV radiation not only can come into being the active free oxygen[O]which is benefit for removing the noncellulosic substances,but also take reaction with the photoconductive group such as carbonyl group on lignin molecular chain.These reactions can destroy and damnify the exterior of pectin layer,and make the degumming process more easily.Under the condition of the concentration of 12g/L NaOH,the concentration of 12g/L H₂O₂,the concentration of 3 g/L MgSO₄,the ultraviolet radiation wave of 280 nm,the stirring temperature of 100℃,the stirring time of 180min,the stirring speef of 180r/min,the heads-and-feet stirring of 20-minute,it was obtained the best degumed hemp fiber,it is not only more whiter and more silken,but also less gum and less gum.The content of residual gum is 2.44%, the content of lignin is 0.73%and the degree of white is up to 67.2.In this paper,the second alkali-H₂O₂ and whisk degumming is replaced with the fire retardancy treatment.This new technics not only bring good effect of degumming,but also have excellent fire resistance with the value of LOI 38.9 %.The special bleaching,pliancy and fire retardant treatment will not be need during the aftertreatment of hemp degumming.So it can reduce the costs and save time to a great degree.