Fiber damage

Wool and Silk. Wool must be caretiiUy bleached to avoid fiber damage. It is usually bleached with 1—5% hydrogen peroxide solutions at pH 8—9 for several hours at 40—55°C or at pH 5.5—8 for 20—60 min at 70—80°C. Silk is bleached similarly, but at slightly higher temperatures. 

Another condition due to mutations in the RYRl gene is central core disease. This is a rare myopathy presenting in infancy with hypotonia and proximal muscle weakness. Electron microscopy reveals an absence of mitochondria in the center of many type I (see below) muscle fibers. Damage to mitochondria induced by high intracellular levels of Ca secondary to abnormal functioning of RYRl appears to be responsible for the morphologic findings. 

At very low moisture, however, fiber damage is significant. An Increase of 30 percent in fiber shorter than 12.5 mm was observed when lint moisture was 3.0 percent rather than 5.7 percent at cleaning time. 

Under the washing conditions of this laboratory experiment -- 5 min with a wetting agent and agitation — temperatures above 60°C appear to offer little benefit in removing extraneous materials and, moreover, may cause fiber damage. Similar results on the effects of temperature on removing solvent and water soluble materials from cotton have been reported by Ross, et al. (6). 

Metal-complex dyes (Sections 2.10 and 3.11) are chemically similar to chrome dyes. The risk of fiber damage during dyeing is reduced because the complex is formed during dye production. 

During dyeing a pH below 2.4 should be avoided, because fiber damage occurs at low pH. 

The thermal degradation of textiles is influenced by the environment in which they exist as well as by impurities, additives, and finishing agents in the fiber. Damage to all fibers by heat and secondary influences such as ultraviolet light and biological attack occurs more rapidly in humid atmospheres. Cotton and silk can withstand higher temperatures than can wool without adverse effects on their fiber properties. 

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