Research On The Structure And Dyeing Properties Of Hemp Fiber With Liquid Ammonia Treatment

Structural changes of hemp fiber with liquid ammonia treatment have been researched by scanning electron microscopy, X-ray diffraction, surface area analyzer and Infrared spectroscopy. The results showed that: with liquid ammonia treatment, the fiber surface becomes smoother, vertical cracks and rough almost disappeared and the degree of crystallization decreased, there is also some changes occurred in grain size; Most of the celluloseⅠtransformed into celluloseⅢ; it also shows that the pore size distribution of the fiber becomes narrower, specific surface area and the accumulation of cavity volume decreased; the intensity of characteristic peak at 896cm-1 enhanced, a new peak emerged at 3475cm-1.It means that stretching vibration of the bond O…H…N occurred on the fiber treated with liquid ammonia, which caused the deviation of the O…H peak.Select different types, structure of direct dyes and reactive dyes, respectively dyeing hemp fabric by dip method in different conditions, such as the amount of salt, alkali concentration and temperature on the staining of chromatin, including rate of dyeing, fixation, drawing uptake curve to obtain each dyes optimum conditions on hemp fabric and evaluate K / S value and color fastness. By comparing the different performance of the fabrics treated with liquid ammonia or not to analyze the dyeing properties affected by the fiber structure changes caused by the liquid ammonia treatment.The results shows that each of the direct dyes performance on the fabric treated with liquid ammonia were poorer than the fabric that not, the dye-uptake of the dye with large molecular was more than the small one. The structure of it also has some effects on the dye-uptake.By dyeing the hemp fabrics treated with liquid ammonia with reactive brilliant blue, reactive violet and yellow, founds that ammonia treatment of dye-uptake, fixation yield and K/S value were higher than the untreated fabric, but the Turquoise Blue of the liquid ammonia treated fabric is poorer than the untreated one. Reactive blue and yellow dyes are more suitable for the hemp fabric than Turquoise Blue Purple and reactive violet. The different dying behavior between the treated fabrics and the one not is attributed to the changes of the fiber structure caused by the liquid ammonia treatment. The distribution of pore diameter is responsible for the direct dyes and the crystallinity for the reactive dyes.