Cellulosic fabrics

Enzymes have traditionally been closely associated with the desizing of cellulosic fabrics. In recent years, however, the sphere of possible, if not actual, uses has widened considerably. 

Most cotton is bleached with peroxide, by far the greater proportion by continuous methods. Synthetic fibres seldom require bleaching, but where it is necessary either peroxide or chlorite bleaches are recommended. Most regenerated cellulosic fabrics are only bleached... 

Table 10.35 Examples of application of the Raco-Yet system to cellulosic fabrics and blends [318]...

Essentially nonionic soil-release agents comprise polyesters, polyamides, polyurethanes, polyepoxides and polyacetals. These have been used mainly on polyester and polyester/ cellulosic fabrics, either crosslinked to effect insolubilisation (if necessary) or by surface adsorption at relatively low temperature. Polyester soil-release finishes have been most important, particularly for polyester fibres and their blends with cellulosic fibres. These finishes, however, have much lower relative molecular mass (1000 to 100 000) than polyester fibres and hence contain a greater proportion of hydrophilic hydroxy groups. They have been particularly useful for application in laundering processes. These essentially nonionic polymers may be given anionic character by copolymerising with, for example, the carboxylated polymers mentioned earlier these hybrid types are generally applied with durable press finishes. 

All the above criteria influence the concentrations of the various components required. Some indication of how they are affected can be gleaned from reference [30]. It is important therefore to consult detailed information from the supplier of the naphthols and bases. Such information available on disc for use on a personal computer has been provided for the batchwise dyeing of cellulosic yams [31] and the continuous dyeing of cellulosic fabrics [32]. 

They were introduced in the late 1940s for the textile printing of cellulosic fabrics under the trade names Alcian (ICI) and Phthalogen (BAY). Both types resulted in the insolubilisation of copper phthalocyanine or related pigments within the fibre, although the respective application techniques differed considerably. Reactive phthalocyanine dyes in the 1960s superseded these early approaches to the attainment of fast bright blues and turquoises on cellulosic fabrics [63]. 

Free formaldehyde is a mixture of formaldehyde, formaldehyde hydrates, and low molecular oligomers. It imparts a characteristic odor to padding bath or padded fabrics (76,77). Cellulosics fabrics are capable of retaining large quantities of free formaldehyde, which are gradually evolved. Because all finishes degrade to some extent, extractable formaldehyde and releasable formaldehyde must be considered with respect to user exposure. 

In addition to fiber and fabric influences on abrasion resistance, chemical finishes must also be considered. Many thermosetting resins used to impart durable press characteristics to cellulosic fabrics reduce their resistance to abrasion as a result of fiber embrittlement. 

Figure 3. Scanning electron microphotograph of cellulose fabric sample before (A) and after (B) flex abrasion...

Apart from cellulose, direct dyes have a strong affinity to wool and polyamide fibers. Blends of cellulose with wool ( half wool ) used to occupy a considerable segment of the market, but are today without any significance. However polyamide (PA) fibers are included in articles made of cellulose fibers to improve dimensional stability, ease of care, and durability, e.g., in sportswear and knitwear, corduroy fabrics, or plush articles, in which a PA pile is often anchored to a cellulose fabric base. Different dyeing methods are described in [50 pp. 433-4371, [6, p. 570],... 

Table II. Color Difference (AE), Standard Deviation (SD) and Grey Scale for Staining Rating (GSS) of Naturally and Artificially Aged Cellulosic Fabrics Immediately After Deacidification1,2, 3... 

Table V. Aqueous Extract pH of Cellulosic Fabrics After Treatment and After Aging at 100°C and 100% RH for 15 Days 1,2...

D. Price, A.R. Horrocks, M. Akalin, and A.A. Faroq, Influence of flame retardants on the mechanism of pyrolysis of cotton (cellulose) fabrics in air. J. Anal. Appl. Pyrolysis, 40 -1, 511-524 (1997). 

A mixture of ammonium chloride and borax was one of the treatments of cellulosic fabrics reported by Gay-Lussac in 1821. Due to its low dehydration temperature and water solubility, sodium borates are only used as flame retardants in cellulose insulation (ground-up newspaper— see Sections 9.2.1.2 and 9.2.2.1), wood timber, textiles, urethane foam, and coatings. For example, a mixture of urethane (100 parts), borax (100 phr), and perlite (30phr) was claimed to provide flame-retardant urethane foam.8 Borax in conjunction with boric oxide, silica, ammonium chloride, and APB as ceramizing additives and volume builders, are claimed in a fire-protection coating based on polybutadiene and silicone microemulsion.9 Using a modified DIN 4102 test, the chipboard with the coating showed a loss of mass less than 1% and there was no pyrolysis of the wood sample. 

In contrast, ASTM E 218722 is a test for assessing the ignition power of cigarettes. In the test, the cigarettes are assessed for their capability of igniting the filter paper (as a surrogate for a cellulosic fabric). In this case, the cigarette is the item to be assessed and not the fabric or the foam. 

Table I. Weather-Resistant Finishes for Cellulosic Fabrics...

Mandels, M. and Reese, E. T., Fungal cellulases and the microbial decomposition of cellulosic fabric. Dev Industrial Microbiol 1964, 5, 5-20. 

Vapor or Spraying Applications. Cyanoethylation. Reaction of cellulose with acrylonitrile, CH2=CHCN, a vinyl monomer, was selected for study because it is known to produce several desirable changes in the properties of cellulosic fabrics and yams. After cyanoethylation, undegraded cotton becomes more resistant to microorganism attack, heat, acid, and abrasion (3). Moisture absorption decreases and the electrical properties change. The extent of these changes varies considerably... 

The most important cotton etherification treatments are those that produce wrinkle resistance in fabrics [331,333,334]. The aldehydes, formaldehydes, and glyoxals, react with the OH groups of two cellulose chains as well as those of one chain. Reaction in which a bond is established between the two cellulose molecules is called cross-linking and is the basis for profound changes in the cotton fiber. Cross-linking produces resiliency in the fiber to give the needed dimensional stabilization, wrinkle resistance, and crease retention for modern durable-press cellulosic fabrics. Cross-links based on etherification reactions traditionally have been used because of their durability to repeated laundering and wear. 

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