Research On The Modification Of Flax Fabric With Chitosan And Its Quaternary Ammonium Salt

In this paper, different molecular weight chitosan and its quaternary ammonium salt were prepared to modify and finish flax fabric, which could solve two problems of flax fabric — poor dyeability and wrinkle recovery performance.The study found that the reactive dyeing dye-uptake and fixation of flax fabric which was modified by chitosan and its quaternary ammonium salt were improved to different degrees. The degree of the improvement depended on the molecular weight of chitosan and treating temperature. But the crockfastness, whiteness, and mechanical properties of the modified flax fabric were decreased to different degrees. The softness of the modified flax fabric showed little change. The wrinkle recovery angle of the modified flax fabric increased. The surface of the modified flax fabric become more smooth. After being modified by low molecular weight chitosan quaternary ammonium salt, the dye-uptake and fixation of low, middle and high temperature reactive dyes of the modified flax fabric were all better than that of the unmodified flax fabric which was accelerated by 40g/L salt. Salts-free dyeing could be implemented on the linen fabric which was modified by low molecular weight chitosan quaternary ammonium slat. The process could achieve the purpose of cleaning production.By means of central composite designs and response surface analysis, the effects of various factors on the reactive dyeing properties of the flax fabric which was modified by chitosan quaternary ammonium salt were found to be in order: the usage amount of chitosan quaternary ammonium salt(HTCC) > soaking temperature > soaking time > curing temperature. Increasing the usage amount of HTCC and raising soaking temperature were two important ways to obtain better dye-uptake of the dyeing system. The optimum modification process which was investigated by response surface analysis was as follows: the usage amount of HTCC(8g/L), soaking temperature(65℃), soaking time(80 min), curing temperature(110℃).Reactive dyeing thermodynamics and kinetics of the flax fabric which was modified by chitosan quaternary ammonium salt were investigated. The results showed that the curve of dyeing rate of modified flax fabric conformed to pseudo-second-order model and relatively conformed to pseudo-first-order model in the initial stage of dyeing. The dye-uptake process was the process of non-orientation and multimolecular layer adsorption. The adsorption isotherm conformed to Langmuir model and relatively conformed to Freundlich model. Orientation adsorption and non-orientation adsorption existed between modified flax fabric and reactive dyes. The dyeing equilibrium adsorption capacity and the dyeing affinity of the modified flax fabric decreased as the temperature rose. Both dyeing enthalpy and entropy were negative value, which conformed to the normal dyeing process.Low molecular weight chitosan(LMWCTS) and polybasic carboxylic acid were jointly used to finish flax fabric in order to improve the anti-wrinkle properties. The optimum creaseresistant finishing process was as follows: LMWCTS(12.5%), CA(15%), MA(12.5%), SHP(20%), curing temperature(180℃), curing time(180s). Comparing to the unmodified flax fabric, polybasic carboxylic acid finished flax fabric and low molecular weight chitosan finished flax fabric, it was found that the optimum crease-resistant process finished flax fabric had the best anti-wrinkle properties and durability. The finished flax fabric had a decreased whiteness and softness. The mechanical properties decreased obviously. The constitution and structure of the finished fabric did not change apparently. The surface of the finished fabric became more smooth and had a coated sense.