Yellow-dyed silk robes were so precious to ancient Chinese emperors that they permitted no one else to wear them. These emperors also limited silk-wearing to the nobility, assigning certain colors in accordance with their rank. Confucius attributed the Chinese empress Xi Ling-Shi (http://en.wikipedia.org/wiki/Xi_Ling-Shi) with discovering silk weaving approximately 2640 BCE. For the next 2,000 years, silk farming and dyeing remained a guarded secret in China. As sericulture spread westward, Europeans became as secretive concerning its manufacture as the Chinese ever were. Everyone who came in contact with silk became enthralled with its luxurious beauty. How could such beauty result from mere caterpillar spittle? One answer lies in the unique composition of the protein fibers spun by the cultivated Bombyx mori silkworm and the great affinity they have for dyes. The amino acids comprising the silk fibroin offer a plethora of reactive sites for the dye molecules, resulting in bright rich colors. The fibroin's triangular prism-like structure refracts light at different angles giving the colors a depth and a luster that shimmers and changes as light plays across its surface.
Related Record from CAplus
115: 73529 Low-temperature dyeing of real silk fabrics using a redox system. Luo, Jutao. Zhejiang Text. Sch., Ningbo, Peop. Rep. China. Journal of the Society of Dyers and Colourists 1991, 107(3), 117-20 (Eng). A low-temp. dyeing redox dyeing system was investigated and it was shown that exhaustion and fixation of acid dyes are improved in the low-temp. dyeing of silk fabrics when a H2O2/glucose redox system is present. The redox system causes an increase in the no. of dyeing sites on the silk through the action of free radicals, which, it was postulated might assist covalent fixation, in an addn. to the usual ionic links, H bonds, and van der Waals forces which bind the dye to the substrate.
81: 38721 Adsorption of dyes by silk fibers. IV. Dyeing properties of Orange I and Orange II on silk fiber Bombyx mori. Kato, Hiroshi. Sericult. Exp. Stn., Tokyo, Japan. Sanshi Kenkyu 1973, (86), 99-115 (Japan). The adsorption equil. of Orange I [523-44-4] and Orange II [633-96-5] on silk fibers was detd. at 40o, 60o, and 80o and the equil. amt. adsorbed decreased with increasing temp. at pH > 3.1-3.3 and was dependent on the no. of dye sites, dye mol. lengths, polyamide chain segment mobility, and fine structure. The temp. effect was discussed using the concept of lateral order distribution. Thermodn. values were calcd. using the Gilbert-Rideal Rideal theory which fit the data better than the Donnan theory. The adsorption isotherms followed Langmuir's formula which calcd. the satd. adsorption of Orange II to be equal to that of HCl, thus indicating that most of the adsorption was attributable to ionic linkages between basic sites such as terminal and side amino groups and dye anions.
125: 303119 Studies on dyeing of silk with different classes of dyes. Part IV. Blue dyes. Gulrajani, M. L.; Dhanjal, Sona; Kapur, Veena; Agarwal, Deepali. Textile Technology Dep., Indian Inst. of Technology, New Delhi, India. Colourage 1996, 43(7), 41-44, 46-50 (Eng). The degree of exhaustion of acid, direct, and metal-complex dyes was very high with silk, giving good color yield. Among the reactive dyes, bifunctional Sumifix Supra dyes showed good exhaustion. The color yield of other reactive dyes was not very satisfactory. A wide range of blues was obtained, ranging from turquoise to navy blue to violet. Fastness properties of reactive dyes were very good, followed by those of metal-complex, direct, and acid dyes. Several dyes of the acid, metal-complex, or reactive class could be alternatives to banned direct blue dyes.
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