Mercerization

Mercer J L Jr and Chou M Y 1994 Tight-binding model with intra-atomic matrix elements Phys. Rev. B 49 8506... 

Mercer A D 1990 Corrosion in Seawater Systems (New York Eiiis Horwood)... 

Department of Chemistry and Courant Institute of Mathematical Sciences, New York University and The Howard Hughes Medical Institute, 251 Mercer Street, New York, NY 10012, U.S.A. 

Cotton Mercerizing and Scouring. An estimated 1.7% of caustic soda consumption goes into cotton mercerizing and scouring. The majority is used for mercerizing and demand is expected to decline between 2.5 and 5%/yr (6). 

The blanket of alk-ceU leaving the slurry press is shredded, and if necessary cooled, before being conveyed to mercerizing (the ripening or aging process). 

T. W. Goodwia and E. I. Mercer, Introduction to Plant Biochemistry, 2nd ed., Pergamon Press, Oxford, 1983. 

W. E. Mercer and J. E. HiUis, The Critical Contaminant Eimits and Salt Water Corrosion Peformance of Magnesium AIE42 Alloy, paper 920073, Society of Automotive Engineers, Detroit, Mich., 1992. 

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). 

Mercer Management Consulting Report on the U.S. Vaccine Industry to the U.S. Dept. Health and Human Services, Washiugtou, D.C., Juue 14, 1995. 

The largest use of zinc chloride in the United States is in wood preservation, fluxes, and batteries (see Batteries). Zinc chloride solution dissolves vegetable fiber and is widely used in mercerizing cotton (qv), swelling fibers, as a mordant in dyeing, parchmentizing paper, etc (see Fibers, vegetable ... 

Mercerized cellulose fibers have improved luster and do not shrink further. One of the main reasons for mercerizing textiles is to improve their receptivity to dyes. This improvement may result more from the dismption of the crystalline regions rather than the partial conversion to a new crystal stmcture. A good example of the fundamental importance of the particular crystal form is the difference in rate of digestion by bacteria. Bacteria from cattle mmen rapidly digest Cellulose I but degrade Cellulose II very slowly (69). Thus aHomorphic form can be an important factor in biochemical reactions of cellulose as well as in some conventional chemical reactions. 

Cellulose III. Cellulose III results from treatment of cellulose with Hquid ammonia (ammonia mercerization) or amines. Cellulose III can be made from either Cellulose I or II. When treated with water. Cellulose III can revert to its parent stmcture. Some cellulose III preparations are much more stable than other preparations. The intensities on diffraction patterns from Cellulose III differ slightly depending on whether the Cellulose III was made from Cellulose I or II, and thus these allomorphs are called IIIj or IHjj- Workers studying III concluded, based partiy on the results of I and II, that the packings of IIIj and IIIjj are parallel and antiparallel, respectively (67). IIIjj also is thought to have hydrogen bonds between the corner and center chains. 

In one process to produce highly activated cellulose for acetylation, cellulose is treated with NaOH (mercerization) followed by a hydroxyalkylating agent, eg, ethylene oxide or propylene oxide, to give a cellulose hydroxyalkyl ether with a DS of 0.05—0.3 (76). The resulting water-insoluble material is highly reactive to conventional acetic anhydride—sulfuric acid acetylation. 

Conversion to cellulose II and cellulose III via caustic mercerization and Hquid ammonia treatment are commercial textile processes that are discussed later. Figure 7 shows the characteristic diffractograms (CuKa radiation) of native cellulose, cellulose mercerized with sodium hydroxide, and cellulose treated with Hquid ammonia. 

Fig. 8. Internal volume (FQ that is accessible to sugars as functions of the cotton molecular diameters (33). (a) Batting A, greige , scoured—bleached , caustic mercerized H, Hquid ammonia treated, (b) Fabric 0> scoured—bleached V> cross-linked.

Scouting and bleaching slightly increase the accessible internal volume, Hquid ammonia treatment of the scoured—bleached cotton decreases it slightly, caustic mercerization substantially enhances accessibiHty, and cross-linking to impart durable press properties reduces this accessible internal pore volume substantially. 

---