The chemical structure of cotton cellulose macromolecules is composed of β-D glucose residues linked to each other by 1,4 glycoside bonds. The two terminal glucose residues of the macromolecule c...
The chemical structure of cotton cellulose macromolecules is composed of β-D glucose residues linked to each other by 1,4 glycoside bonds. The two terminal glucose residues of the macromolecule carry different groups. One end has four free hydroxyl groups, and the other end has four free hydroxyl groups. There are three free radicals and one hemiacetal hydroxyl group �纤维素大分子链中的贰键对碱的稳定性较高，对酸则易发生水解，使大分子聚合度下降，分子间力减弱，因而强度下降� �</p
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目前纤维素对碱的作用机理说法不一，但普遍认为，碱只能与纤维大分子上的轻基发生作用� �有人将浓碱与纤维素作用后的产物用醇等试剂长时间冲洗，却总有部分碱洗不掉，说明碱确实与纤维素发生了化学反应� � </p
There are two theoretical explanations for its working principle: one view is that cellulose is a weak acid; it undergoes a similar neutralization reaction with alkali to form a sodium alcohol compound; the other view is that the alkali combines with the light group of cellulose to form a molecule compound, i.e. molecular combination theory �</p
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一般认为以上两种反应可能同时存在� However, the product of the interaction between alkali and cellulose is called alkali cellulose. It is an unstable compound. It can still restore the original cellulose molecular structure after being washed with water, but the microstructure of the fiber has changed and the crystalline area has been reduced. Amorphous zone increased The crystallinity of natural cotton fiber is 70%. The crystallinity of mercerized cotton fiber after being treated with concentrated alkali is reduced to 50% to 60%. This shows that the alkali liquid puffs the fiber and destroys some of the crystallization areas. This effect is very effective. Practical significance, it is an important link in the dyeing and finishing of cotton fiber. �</p
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因此，在染整加工中利用不同浓碱的作用可得到丝光、碱缩等效果，还可以生产泡泡纱等产品。纤维素纤维遇酸后，常表现出手感变硬、强度降低，甚至会全部炭化。这是由于酸对纤维素分子中甙键水解起催化作用，水解后形成聚合度不同的混合物，被称为水解纤维素。水解纤维素的化学组成与原纤维素并无区别，只是聚合度较低，纤维素相对分子质量具有更大的多分散性。水解纤维素若继续与酸作用，聚合度降至50左右称为纤维素糊精。
如果纤维素甙键完全水解断裂则产物就是葡萄糖。影响纤维素水解的因素主要是酸的性质、反应温度及作用时间。
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在实际生产中，如果用酸工艺适当，就不会产生纤维严重损伤。酸与纤维素作用的一般规律是，酸性愈强，催化能力愈强，水解速度加快。强无机酸如盐酸、硫酸、硝酸对纤维素水解特别强，弱酸如磷酸、硼酸催化活性较弱；有机酸如醋酸则更缓和。酸对纤维素纤维虽有危害，但只要控制得当，仍有许多实际用处。
If the fabric is bleached with chlorine-containing bleach and then treated with dilute acid, the bleaching effect can be further enhanced; acid can be used to neutralize the remaining alkali on the fabric; cotton fabrics are treated with acid to produce organza; products such as burnout sheaths for polyester-cotton fabrics are There are applications
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