Raw silk

Takeuchi et at. [60] reported that cloth made of raw silk (R-silk) fiber forms hydroxyapatite in 1.5SBF but cloth made of normal silk (N-silk) fiber does not. The surfaces of raw silk and normal silk fibers consist of sericin and fibroin, respectively. 

The first spinning experiments were performed with dissolved raw silk of the silkworm Bombyx mori [31] and the golden orb-weaver Nephila clavipes [32]. For this purpose a minimized wet-spinning apparatus was constructed [31]. The apparatus was capable of spinning fibers from solutions containing 10 mg of soluble protein. 

Raw silk was dissolved in hexafluoro-iso-propanol (HFIP) [17, 33]. A typical working concentration for spinning was 2.5% (w/v) silk fibroin in HFIP. The spinning solution was pressed through a small needle (0 80-250 pm) into a precipitation bath (methanol for Bombyx mori silk proteins and acetone for Nephila clavipes silk proteins) and the silk solution immediately precipitated as a fiber. The best performing fibers approached the maximum strength measured for native fibers of Bombyx mori, but did not achieve the mechanical properties of natural spider silk. 

L- Serine <10 Synthesis from glycoloniuile and resolution Rich in raw silk... 

In this connection it must be borne in mind that in some of these extraction tests on naturally coloured and raw cotton, flax, wool, hair, etc, an appreciable quantity of yellowish-brown colouring matter is removed, and that raw silks of a natural yellow or green colour exhibit special behaviour if subjected to some of these tests, eg, to treatment with concentrated acids ... 

The difference between this weight p and that of a metre of the raw silk fibre3 will give the weighting. 

According to Ristenpart, the mean weight of a metre of raw silk fibre may b taken as ... 

Silk is an animal fiber valued for its texture, strength, and luster. First prepared in ancient China, silk fabric was expensive, luxurious, and soft its popularity led to the development of a trade route known as the Silk Road leading from Asia to Europe. Early American entrepreneurs such as Benjamin Franklin promoted the silk industry in the colonies. Silkworms spin cocoons that are collected, steamed, and unwound to obtain the silk fiber by a process known as reeling. A number of fibers are twisted together to form a thread of raw silk. Threads are combined, cleaned, stretched, dyed, and woven into fine fabrics. Silk fibers have great tensile strength and are sometimes used in cordage. 

Silk fibers are smooth, translucent, rod-like filaments with occasional swellings along their length. The raw silk fiber actually consists of two filaments called fibroin bound by a soluble silk gum called sericin. Fibroin and sericin are made up of carbon, hydrogen, nitrogen, and oxygen. 

The next step in sericulture is to unwind the cocoon. This process is called reeling. To produce uniform strands of raw silk for commercial use, filaments of 5-10 cocoons are combined into a single thread. To do this, the cocoons are first soaked in hot water. After the ends of the filaments have been located, the filaments are passed through porcelain guides where they are twisted into fibers of uniform length and regularity. Reeling may be done automatically or by hand. 

Raw silk is wound into skeins. Thirty skeins constitute one book, which weighs around 4.3 lb (1.95 kg). Thirty books make a bale, which weighs 132.3 lb (60.06 kg). The bale is the basic unit of commercial transactions. About 900 lb (408.6 kg) of cocoons are required to produce one bale of raw silk. 

The morphological stmcture of raw silk fibre is given in Fig. 1-10. The actual fibre protein is called fibrion and the protein sericin is the gummy substance that holds the filament together. The average composition of raw silk is 70-75% fihrion (CijHj NjOg), 20-25% sericin, 2-3% waxy substances extractable by ether and alcohol and 1 to 1.7% mineral matter. Sericin is amorphous and dissolves in hot soap solution. Fibrion is the form of a filament thread and dissolves in 5% sodium hydroxide solution at boil. 

Figure 1-10. The structure of raw silk fibre, amino acids is shown in Table 1.10. Fibrion contains hardly any sulphurous amino TABLE 1.10...

Degumming or boiling-off is the process employed to remove the silk gum (sericin) enveloping the two raw silk threads (fibrion) (Fig. 4-14). During the... 

Thrown silk or grege consists of two or more threads of raw silk reeled together and given a slight twist. Thrown silk is used for making organzine and tram. 

Besides fibroin and sericin raw silk contains small quantities of mineral matter, traces of fat, colouring matter and water. The average composition is ... 

I his presents special features because it is usually accompanied by the removal of the silk gum or sericin. The process is commonly referred to as boiling off . Souple silk is raw silk from which about 10 per cent of the gum has been removed, and in ecru only about 4 per cent is taken away, the object being to cleanse the silk rather than to degum it. The boiling off, which depends upon the solubility of sericin in hot soap solution, with the possible addition of mild alkali, is the same for complete degumming, souple or ecru differing only in the time of treatment. 

Ishida, S. (1901) Bull. Japan Assoc. Raw Silk (Japanese), 9, 1. 

And coloured like Astarte s eyes Raw silk the merchant sells ... 

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