Lụa là một sợi protein động vật được sản xuất bởi một số côn trùng để xây dựng cocoons và webs của họ.Nhiều loại khác nhau của lụa được sản xuất bởi một loạt lớn các loại khác nhau của các côn trùng khác hơn so với sâu bướm bướm đêm. Được không ai trong số này đã được khai thác cho mục đích thương mại, mặc dù đã từng có các nghiên cứu cơ bản vào các cấu trúc của vải sợi như vậy. Lụa phổ biến nhất được sản xuất bởi ấu trùng, và do đó chủ yếu là giới hạn để côn trùng với biến thái hoàn thành.Trong một số trường hợp, Tuy nhiên, nó được sản xuất bởi các côn trùng dành cho người lớn chẳng hạn như webspinners. Sản xuất lụa đặc biệt phổ biến trong bộ cánh màng (ong, ong bắp cày và kiến), và đôi khi được sử dụng trong xây dựng tổ. Các loại động vật chân đốt sản xuất lụa, đáng chú ý nhất nhện khác nhau chẳng hạn như nhện. Lụa được sản xuất bởi côn trùng khác, chủ yếu là nhện, được sử dụng trong một số ít các ứng dụng thương mại, ví dụ: vũ khí, kính thiên văn, và các dụng cụ quang học.Quá trình thương mại tơ lụa làm là rất phức tạp và lao động chuyên sâu. Sau đây sẽ cung cấp thông tin cơ bản về làm thế nào lụa được thực hiện.[Cho thông tin chung lụa, vui lòng truy cập về lụa vải, nằm trên một chủ đề liên quan khác nhau, chẳng hạn như lụa chăm sóc & Hấp, lợi ích của lụa, và lịch sử Trung Quốc Silk.]NhoTrứng để ấpGiai đoạn cho ănQuay CocoonCuộn dây tócLoại lụaNhoCultivation of the silkworm is known as sericulture. Although many insects produce silk, only the filament produced by Bombyx mori, the mulberry silk moth and a few others in the same genus, is used by the commercial silk industry.[The “silkworm” is, technically, not a worm but a moth pupa. For the sake of simplicity and consistency, however, we will use the term silkworm throughout this writing.]Hatching the EggsThe first stage of silk production is the laying of silkworm eggs, in a controlled environment such as an aluminum box, which are then examined to ensure they are free from disease. The female deposits 300 to 400 eggs at a time.In an area the size of your monitor screen, 100 moths would deposit some 40,000 eggs, each about the size of a pinhead. The female dies almost immediately after depositing the eggs and the male lives only a short time after. The adult possesses rudimentary mouthparts and does not eat during the short period of its mature existence.The tiny eggs of the silkworm moth are incubated (about 10 days) until they hatch into larvae (caterpillars). At this point, the larva is about a quarter of an inch long.The Feeding PeriodOnce hatched, the larvae are placed under a fine layer of gauze and fed huge amounts of chopped mulberry leaves during which time they shed their skin four times. The larvae may also feed on Osage orange or lettuce. Larvae fed on mulberry leaves produce the very finest silk. The larva will eat 50,000 times its initial weight in plant material.For about six weeks the silkworm eats almost continually. After growing to its maximum size of about 3 inches at around 6 weeks, it stops eating, changes color, and is about 10,000 times heavier than when it hatched.The silkworm is now ready to spin a silk cocoon.Spinning the CocoonThe silkworm attaches itself to a compartmented frame, twig, tree or shrub in a rearing house to spin a silk cocoon over a 3 to 8 day period. This period is termed pupating.Silkworms possess a pair of specially modified salivary glands called sericteries, which are used for the production of fibroin – a clear, viscous, proteinaceous fluid that is forced through openings called spinnerets on the mouthpart of the larva.Liquid secretions from the two large glands in the insect emerge from the spinneret, a single exit tube in the head. The diameter of the spinneret determines the thickness of the silk thread, which is produced as a long, continuous filament. The secretions harden on exposure to the air and form twin filaments composed of fibroin, a protein material. A second pair of glands secretes a gummy binding fluid called sericin which bonds the two filaments together.Steadily over the next four days, the silkworm rotates its body in a figure-8 movement some 300,000 times, constructing a cocoon and producing about a kilometer of silk filament.Reeling the FilamentAt this stage, the cocoon is treated with hot air, steam, or boiling water. The silk is then unbound from the cocoon by softening the sericin and then delicately and carefully unwinding, or 'reeling' the filaments from 4 - 8 cocoons at once, sometimes with a slight twist, to create a single strand.As the sericin protects the silk fiber during processing, this is often left in until the yarn or even woven fabric stage. Raw silk is silk that still contains sericin. Once this is washed out (in soap and boiling water), the fabric is left soft, lustrous, and up to 30% lighter. The amount of usable silk in each cocoon is small, and about 2500 silkworms are required to produce a pound of raw silk.Types of SilkRaw silk is twisted into a strand sufficiently strong for weaving or knitting. This process of creating the silk yarn is called “throwing,” and prevents the thread from splitting into its constituent fibers.Four different types of silk thread may be produced from this procedure: crepe, tram, thrown singles, and organzine. Crepe is made by twisting individual threads of raw silk, doubling two or more of these together, and then twisting them again. Tram is made by twisting two or more threads in only one direction. Thrown singles are individual threads that are twisted in only one direction. Organzine is a thread made by giving the raw silk a preliminary twist in one direction and then twisting two of these threads together in the opposite direction.In general, organzine thread is used for the warp threads of materials, tram threads for the weft or filling, crepe thread for weaving crinkly fabrics and a single thread for sheer fabrics.Broken or waste filaments and damaged cocoons are retained, treated to remove the sericin, and combed. This is then processed into yarn, marketed as spun silk, which is inferior in character to the reeled product and much cheaper.
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