Copper silk

Cuprammonium Process. In the cuprammonium (cuoxam) process, linters or high-quality wood pulp is dissolved in [Cu(NH3)4] [OH] " (cuoxam). The method varies slightly according to whether copper silk (Bemberg silk) or cell glass (Cellophane ) is required. 

To prepare copper silk, the cellulose is dissolved in a 25% ammonia solution with 40% copper sulfate, and 8% NaOH is then added. During... 

To prepare cell glass (cellulose hydrate films), it is necessary to use higher concentrations of cellulose, otherwise the freshly produced film would contain too much solvent and therefore would tear too readily. Thus, unlike copper silk, it is not possible to start with copper sulfate, since too much NaS04 would result, causing the solubility of the cuoxam solution to fall. A basic copper sulfate, or better still, Cu(OH)2, is therefore used. 

In contrast to cotton cellulose, the resulting wood pulp always retains a small percentage of low-molecular-weight foreign polyoses, mostly pentosans. Further, some carbonyl and carboxyl groups always remain. The fibers are 1-3 mm long, and therefore generally cannot be spun. They are converted to man-made fibers by the viscose or copper silk process. 

Solder mask over bare copper, silk screen one side only... 

Schweitzer s reagent (dissolves cotton, linen, and silk, but not wool) add NH4CI and NaOH to a solution of copper sulfate. The blue precipitate is filtered off, washed, pressed, and dissolved in ammonia (sp. gr. 0.92). 

Direct dyes azo dyes, and sodium salts, fixing agents, and metallic (chrome and copper) compounds used generally on cotton-wool, or cotton-silk combinations. 

Halb-schatten, m. half-shade, half-shadow Astron.) penumbra. -schwefeleisen, n. iron hemisulfide (supposedly Fe2S). -schwe-felkupfer, n. cuprous sulfide, copper (I) sulfide. -seide, /. half-silk, -seite, f. half-page, halb-seitig, a. relating to one side or half, unilateral half-page, -selbsttatig, a. semiautomatic. -sicher, a. metastable, -spezi-fisch, a. semispecific. 

Zhou, L., Chen, X., Shao, Z., Zhou, P., Knight, D. P., and Vollrath, F. (2003). Copper in the silk formation process of Bombyx mori silkworm. FEBS Lett. 554, 337-341. 

SCHWEITZER S REAGENT. A solution of copper hydroxide in strong ammonia used in analytical chemistry as a test for wool. It dissolves cotton, silk, and linen. 

With silk which has undergone change, the sample is enclosed in a little bag of cotton cambric—to avoid losses—and then subjected to the above treatment, the Kjeldahl process being subsequently carried out on the bag containing the treated silk 20 c.c. of concentrated sulphuric add, 10 grams of pure potassium sulphate and 0 5 gram of dried copper sulphate are used see Vol. I, p. 122), complete decolonisation requiring about half an hour. 

The most important aspect of this project was the time line. In mid-1996 the specific polymer composition was selected, and in April 1997 Dow publicly announced what became known as SiLK Semiconductor Dielectric. In April 2000, IBM reported the complete integration of the SiLK dielectric and copper wiring and announced its intent to commercially fabricate integrated circuits using SiLK resin. 

Natural fibers such as cotton can be chemically modified to form rayon or acetate. Rayon was first called artificial silk. In the viscose process, cellulose is dissolved in sodium hydroxide, pushed through spinnerets, and treated with acid to harden. Treatment with copper compounds and ammonia is used to form hosiery yams. Acetate (or cellulose acetate), produced by treating cotton with acetic acid and acetic anhydride, is also used in production of clothing. 

Technical Observations. Tetrazotized benzidinedicarboxylic acid gives, with 2 moles of l,8-aminonaphthol-2,4-disulfonic acid (Chicago acid, see page 217), a disazo dye which, in tlie form of its copper compound on viscose silk, gives a bright blue shade having extraordinary light fastness. 

Figure 10. An 18th century painted Chinese silk showing heavy use of white lead ground layer and copper green pigment. (Acc. No. 32554, courtesy of the Mus ee Historique des Tissus, Lyon.)...

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