Mercerization strength

New International Dictionary, Merriam Co, Springfield, Mass(195I), 73 Alperox C. Trade name for tech lauroyl peroxide manufd by the Lucidol Division of Wallace Tieraan, Inc, Buffalo, NY Alpha-Cellulose is that portion of cellulosic materialfpulp, paper, etc) which,after treatment with 17,5% NaOH(mercerized strength) at 20° and diln to 7.3% NaOH,can be separated by filtration. The residue of alpha-cellulose is a good index of the undegraded cellulose content of the material. The alkali treatment removes degraded(oxidized or hydrolyzed) cellulose and short chain material. Some pentosans and hexosans may... 

Beta Cellulose refers to that portion of industrial cellulose pulps which is sol in cold NaOH of mercerizing strength 17.5 18%) but is pptd on acidification (See also Alpha-Cellulose and Gamma-Cellulose)... 

Cellulose undergoes chemical, physico-chemical and structural modifications on treatment with caustic soda solution of mercerizing strength [5]. Chemical reactions lead to the formation of alkali cellulose, physical reactions, to a change in arrangement of units of cellulose. The optimum modifications in the properties of... 

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. 

On treatment with NaOH solution of mercerizing strength, the cellulose I pattern of purified flax completely transforms to the cellulose II pattern. In other natural cellulosic fibers (except ramie), this transformation is only partial [124]. The degree of crystallinity of flax is estimated to be 70% [113]. 

X-ray diffraction photographs of ramie show the sharp characteristic patterns of cellulose I. The degree of crystallinity of ramie (native cellulose) by x-ray methods is generally estimated to be about 70% [19,113]. In other studies, the estimates range from 74% in the dry state to 54% in the moist state [124]. The treatment with NaOH solution of mercerizing strength completely transforms the cellulose I pattern to cellulose II [169] and reduces the degree of crystallinity to 50% [113]. On the other hand, treatment with dilute NaOH (about 5% solution) increases the crystallinity [185] the same is true for acid hydrolysis [19]. 

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). 

When crystalline cellulose I is treated with aqueous alkali solutions of sufficient strength, a process known as mercerization takes place. As a result of it, cellulose I is converted to cellulose II, the most stable or the four crystalline cellulose polymorphs. The conversion proceeds in the solid state, without apparent destruction or change in the fibrous morphology of the cellulose. As our diffraction analysis indicates, however, it is accompanied by a reversal of the chain packing polarity—from the parallel-chain cellulose I to the... 

Hot dilute or cold concentrated acids disintegrate the fiber, similar u> cotton. Strong alkaline solutions cause swelling and reduce strength. Can be mercerized. 

Mercer, K.L. and Tobiason, J.E. 2008. Removal of arsenic from high ionic strength solutions Effects of ionic strength, pH, and preformed versus in situ formed HFO. Environmental Science and Technology, 42 3797-802. 

The swelling of cotton with an aqueous solution of sodium hydroxide is an important com mercial treatment. It is called mercerization after its discoverer, John Mercer, who took a patent on the process in 1850 [308]. Other alkali metal hydroxides, notably lithium hydroxide and potassium hydroxide, will also mercerize cotton, but normally sodium hydroxide is used. Mercerization is utilized to improve such properties as dye affinity, chemical reactivity, dimensional stability, tensile strength, luster, and smoothness of the cotton fabrics [309]. The treatment is normally applied either to yarn or to the fabric itself either in the slack state to obtain, for example, stretch products, or under tension to improve such properties as strength and luster. The interaction of alkali metal hydroxides and cellulose has been extensively reviewed. Earlier reviews can be traced from relatively recent ones [99,310,311]. 

The effects of cellulase enzymes on cotton substrates that were dyed with various classes of dyes have been reported. It was found that vat dyes do not inhibit cellulase activity on cotton, and hydrolysis of the substrate with subsequent color removal transpires. In contrast, cellulase activity on cotton was inhibited by the presence of some direct and reactive dyes. There is the probability that a dye-enzyme complex is formed with less activity than that of the free enzyme. The increased weight loss from enzymatic treatment on untreated cellulose is associated with a slight reduction in dye sorption, and this may be because of a reduction of amorphous regions in cellulose where dye molecules are usually sorbed. Cellulase activity is more prominent on mercerized cotton than on unmercerized cotton. This is because mercerization is associated with a decrease in the crystallinity of the cellulosic structure [540]. One major negative aspect of cellulase treatment of cotton fabric is the strength loss associated with the approximately 3-5% weight reduction under normal treating conditions. Of course, this is to be expected after cellulose is hydrolyzed. Future research efforts may lead to processes in which enzymes... 

MERCERANT BEA is completely soluble in up to 25% caustic as well as in water, and its use accelerates wetting of fabric and yarn by high strength caustic, resulting in more rapid and complete penetration and thus in improved strength, luster, and absorbency. 

MERCERANT BEA can also be used as a wetting agent in low strength caustic (e.g. 5%) at elevated temperatures (eq. 180F). Under these conditions 1 g/1 or less gives excellent wetting. 

Modified rayon is made principally of regenerated cellulose and contains nonregenerated cellulose fiber-forming material, for example, a fiber spun from viscose containing casein or other protein (ASTM). This greatly increases both dry and wet strength and also permits mercerization. Rayon is readily dyed by standard methods. 

Mercerization improves dimensional stability of cotton woven fabrics [63]. When knitted fabrics are compared with respect to their relative openness, temperature increases can be said to improve mercerization because when the goods are bleached and then mercerized, the fabric becomes more dense. However, when unbleached fabrics are mercerized, the fabrics become more open [64]. Mercerization also gives moderate improvement in crease recovery of cotton fabrics [65] as well as some protection against the decrease in tensile strength caused by easy-care finishing. 

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