Study On The Pretreatment Technology And The Micro-structural Changes Of West-European Dew Retting Flax Fibers

In this paper, it used a single process of sodium hydroxide and hydrogen peroxide toprocess the western European flax fiber and dew which is a traditional way of process, whilediscussing the process, it also tested the surface and microstructure of flax fiber. In order toavoid the complex flax fiber components, which make the faults as samples are difficult toidentify, the thesis did a reverse research of bleaching process of flax fiber dissolved somepigment by test the flax fiber residual liquid during the pretreatment process.The experimental results show that, firstly, sodium hydroxide single process can removepectin layer, low degree of polymerization of pectin, hemicellulose, and lignin of surfacecoverage, but for flax fiber internal pectin, lignin removal effect is limited. Secondly, ingeneral, the whole hydrogen peroxide single process removal effect on fiber attachment isbetter than the single process of sodium hydroxide which cannot effectively remove packagesof flax fiber surface, low ester pectin layer of pectin, hemicellulose, but only have gentleremoval effect. Thirdly, with the augmentation of the pretreatment process of the processconditions, treatment effect of scouring and bleaching processing effects are enhanced.During the process of scouring and bleaching, flax fiber pretreatment of cellulosestructure did not change the nature of the structure and crystallization area, meanwhile, crystaltype basic remain unchanged. Compared with hydrogen peroxide, sodium hydroxide candirectly destroy crystalline crystallize area to reduce.From scanning electron microscope and infrared spectrum graph, it can be concluded thatpectin can’t be completely hydrolyzed in a short time, for the hydrolysis of pectin underalkaline condition is not very strong, it can just prompt pectin stripping from the fiber.After hydrogen peroxide bleaching of single technology, infrared spectrums of flax fiber1500~2500cm-1region have obvious depression. This area is the vibration area of the threekey and the accumulate double bond area, which shows that hydrogen peroxide of flax fiberhas high accessibility and wide range of oxidation, it destroyed a large number of lignincontaining hair base group and pigment hair base group, that is a large number of doublebonds structure destroyed by oxidation.Bleaching liquid pigment structure was destroyed, bleaching liquor is colorless, whereaspectin can also occur normally, it can be seen that flax mixed and pure pectin structurewithout connections to each other. Flax fiber primary colors may be composed of lignin and pigment, which can dissolve inthe solvent of coloring ultraviolet absorption wavelength of327nm, its corresponding colorfor the green light yellow, at high concentration for brown. The bleaching process iscompleted while in the residual liquid increasing the part of methyl and hydroxyl into etherbond together. Contrast scouring residual liquid, soluble pigment may be the flavonoidsintermolecular hydrogen bond hair color.