Alkali Treatment Of Cotton-straw Fiber/Cotton Blended Yarn And Its Properties

Cotton-straw fiber is a kind of new natural cellulose fiber. The alkalimercerization treatment of cotton-straw fiber/cotton blended yarns wasinvestigated.The single factor analysis was used to analyze the influencing factor ofalkali treatment. Then the orthogonal experimental design and fuzzy comprehensiveevaluation method were used in order to obtain the parameters of alkali mercerizationprocess. In conditions of the optimal parameters, the modified blended yarn wastested and evaluated comprehensively. The morphology of modified cotton-strawfiber/cotton blended yarn was observed by SEM. The yarn crystalline was calculatedby X-ray diffraction analysis method.The experimental results showed that optimum process conditions of the alkalitreatment was following as: NaOH concentration200g/L, temperature20℃, time200s, bath ratio1:50. The break strength of cotton-straw fiber/cotton blended yarnswith three different blending ratio (0/100、20/80、50/50) before the alkali treatmentwas5.50cN/tex,5.15cN/tex, and4.35cN/tex, respectively; the moisture regain was7.32%,8.00%, and8.15%, respectively; the shrinkage in water was1.20%,2.50%,and3.50%, respectively. The break strength of the alkali mercerization treatedblended yarns was6.10cN/tex,5.75cN/tex and5.12cN/tex, respectively; themoisture regain was8.75%,9.00%and9.21%, respectively; the shrinkage in waterwas1.05%,1.12%and1.20%, respectively. The barium value of the alkalimercerization treated blended yarns was137,145and151, respectively. All alkalimercerization treatment yarns increased lustrous degree, breaking strength, moistureregain, better adsorption property and straightness. But the yarns had a low shrinkagein water. The break strength of the alkali reduction treated blended yarns was6.00cN/tex,5.20cN/tex and5.10cN/tex, respectively; the moisture regain was8.24%,8.76%and8.90%, respectively; the shrinkage in water was24.85%,35.10%and40.20%, respectively. The barium value of the alkali reduction blended yarns was132,143and144, respectively. All alkali reduction treated yarns had an increase inshrinkage in water, elasticity, breaking strength, moisture regain and adsorptionproperty. The permutation of the fibers was more irregular and the yarns had a wavy morphology.Through the X-ray diffraction test, Gaussian Fitting and peak separation method,the characteristic diffraction positions of the original, alkali mercerization treated andalkali reduction treated cotton yarns were basic agreement with theoretical value ofcellulose I. It showed the type of crystallization still belongs to the cellulose I afteralkali modification. With gauss function of Origin7.5software, we found thatcrystallization of the original cotton yarns was58.8%, crystallization of the alkalimercerization treated cotton yarns was53.6%, and crystallization of the alkalireduction treated cotton yarns was52.7%. Crystallization of the modified yarns wasless than the original yarns. But the crystal structure of cotton-straw fiber/cotton (50/50) blended yarns was changed after alkali modification. Besides characteristic ofcellulose I, another new diffraction peaks appeared characteristic of celluloseⅡ,considering that parts of cellulose I transformed to cellulose Ⅱafter alkali treatment.The crystallization of the original blended yarns was54.7%, crystallization of thealkali mercerization treated blended yarns was50.1%, and crystallization of the alkalireduction treated blended yarns was47.8%. The crystallization of the modified yarnswas reduced.