Mercerization, effect tension

The effect and action of enzymes seems to be very limited because ol the stronger conditions of alkali of mercerizing strength. Enzymatic hydrolysis is accelerated when mercerization is carried out without tension [44]. The greater accessibility and lower crystallinity of cellulose mercerized without tension is a decisive factor in the enzymatic hydrolysis process. Mercerized cotton is generally more prone to enzymatic modification than untreated cotton. 

An important chemical finishing process for cotton fabrics is that of mercerization, which improves strength, luster, and dye receptivity. Mercerization iavolves brief exposure of the fabric under tension to concentrated (20—25 wt %) NaOH solution (14). In this treatment, the cotton fibers become more circular ia cross-section and smoother ia surface appearance, which iacreases their luster. At the molecular level, mercerization causes a decrease ia the degree of crystallinity and a transformation of the cellulose crystal form. These fine stmctural changes iacrease the moisture and dye absorption properties of the fiber. Biopolishing is a relatively new treatment of cotton fabrics, involving ceUulase enzymes, to produce special surface effects (15). 

Mercerization was discovered by John Mercer in England and the process is named after him mercerizing. The process of alkaline treatment of cotton was patented in 1850. Later Horace Lowe in England found that the glazing effect became even more pronounced when cold caustic soda acted on cotton under tension. He discovered the actual mercerizing process and applied for its patent in 1890. 

The effects of slack and tension mercerization on the morphology and accessibility characteristics of remie, flax and cotton fibres are compared [66], Mercer-... 

The action of caustic soda can be used to produce pattern effects. If applied locally without tension the fibres contract and a puckered finish is produced. If a pattern is printed with a paste containing little or no water, and the cloth is then passed through water under tension, a lustrous design appears on a matt background. When dyea, the mercerized portions will be a heavier shade than the remainder. 

J.T. Kim, and A.N. Netravili, Mercerization of sisal fibers Effects of tension on mechcuiiccil properties of sisal fibers and fiber-reinforced composites. Compos. A 41,1245-1252 (2010). 

Kim, J.T. and Netravali, A.N. (2010) Mercerization of sisal fibers effect of tension on mechanical properties of sisal fiber and fiber-reinforced composites. Composites Part A, 41 (9), 1245 1252. 

It was later determined that the crystallographic form cellulose I was irreversibly chang to the form cellulose II. The unit cell of cellulose II also contained two cellobiose units with axes a = 0.814 nm, b = 1.03 nm, c = 0.914 nm, and fi = 62° (angle between a and c axes). The fibrillar cellulose II is less ordered than fibrillar cellulose I and is about 60% crystalline. This 1840s development, now called mercerization, is probably the most important process for the modification of natural cellulose, particularly cotton cellulosic textile fibers, to current date. Lowe later confirmed these results and showed the effects of mercerization on cotton fibers while under tension. 

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