Silk fibers temperature, effects

Qiana, introduced by Du Pont in 1968 but later withdrawn from the market, was made from bis(4-aminocyclohexyl)methane and dodecanedioic acid. This diamine exists in several cis—trans and trans—trans isomeric forms that influence fiber properties such as shrinkage. The product offered silk-like hand and luster, dimensional stabiUty, and wrinkle resistance similar to polyester. The yam melted at 280°C, had a high wet glass-transition temperature of - 85° C and a density of 1.03 g/cm, the last was lower than that of nylon-6 and nylon-6,6. Qiana requited a carrier for effective dyeing (see Dye carriers). 

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. 

Johnson et al. [27] report that polysulfone and poly(vinyl acetate) show enhanced low-temperature -loss transitions in proportion to the unclustered water. Clustered water in poly(vinyl acetate) has no effect on Tg, although shifts with increasing amount of unclustered water. Fuzek [3T] found that water absorbed by synthetic fibers and silk at room temperature and 65% RH substantially lowers Tq s, the effect being reflected in several different fiber properties. Wet soaking has an additional effect. 

Since fibers consist primarily of oriented crystallites, it is unfair to classify them as heterophase. However, the generalizations of time-temperature superposition that work so well with amorphous polymers do not apply to fibers. Fibers do exhibit viscoelasticity qualitatively like the amorphous polymers. It comes as a surprise to some that J. C. Maxwell, who is best known for his work in electricity and magnetism, should have contributed to the mathematics of viscoelasticity. The story goes that while using a silk thread as the restoring element in a charge-measuring device. Maxwell noticed that the material was not perfectly elastic and exhibited time-dependent effects. He noticed that the material was not perfectly elastic and showed time effects. The model that bears his name was propounded to correlate the real behavior of a fiber. 

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