氢氧化钠溶液在纺织纤维成分定性鉴别中的应用研究

Research on the application of sodium hydroxide solution in qualitative identification of textile fiber components

研究表明,浓硝酸可以使纤维素类及部分蛋白质纤维发生溶胀或溶解,而氢氧化钠也有相似作用。部分学者有关氢氧化钠/尿素/硫脲溶剂体系对纤维素的溶解性能研究表明,纤维素与氢氧化钠反应生成带负电荷的碱纤维素,当其与水化程度很强的钠离子结合时,有大量的水分被带入纤维素大分子内部,引起纤维素的剧烈溶胀而拆散纤维素无定形区大分子间的结合力,但不能克服晶区大分子间所有的结合力,因此,纤维素在氢氧化钠溶液中有溶胀现象,但不会溶解。为寻找一种不易挥发、危险性较小的溶剂替代浓硝酸在纤维成分定性中的作用,文章探究了显微镜下不同纺织纤维在不同浓度氢氧化钠溶液中的形态变化,并确定了适合纤维定性鉴别的氢氧化钠溶液浓度。

The research shows that concentrated nitric acid can swell or dissolve cellulose and some protein fibers,and sodium hydroxide has a similar effect.Some scholars’studies on the solubility of cellulose in sodium hydroxide/urea/thiourea solvent system show that cellulose reacts with sodium hydroxide to form negatively charged alkali cellulose.When it combines with sodium ions with strong hydration degree,a large amount of water is brought into the cellulose macromolecules,causing severe swelling of cellulose and breaking up the binding force between macromolecules in the amorphous region of cellulose.However,it can not overcome all the binding forces between macromolecules in the crystal region.Therefore,cellulose swells in sodium hydroxide solution,but will not dissolve.In order to find a non-volatile and less dangerous solvent to replace the role of concentrated nitric acid in the qualitative identification of fiber composition,this paper explores the morphological changes of different textile fibers in different concentrations of sodium hydroxide solution under the microscope,and determines the concentration of sodium hydroxide solution suitable for the qualitative identification of fiber.