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Cao su tổng hợp luôn được quan tâm nghiên cứu để đủ thông tin kỹ thuật khi xử lý các đơn pha chế phức tạp. Các sản phẩm cao su bánh xe, các đệm cao su trong điều kiện đặc biệt đều cần những thông tin đầy đủ về các nguyên liệu cao su tổng hợp.
Mời các bạn đọc một ít thông tin về cao su butyl.
Butyl rubber is essentially polyisobutylene, a polymer of isobutylene, which is an isomer of butylene. (Isomers are molecules with the same number of atoms but with different molecular structure and properties.) Isoprene is added during manufacture. Marketed in 1943, after ten years of research work, butyl rubber has enjoyed widespread acceptance because of some of its special properties: low permeability to gases, excellent resistance to oxygen and ozone at normal temperatures, and good resistance to vegetable oils. Butyl rubber is not readily attacked by acids, alkalies, and other chemicals harmful to natural rubber. In addition, it is elastic, odourless, nontoxic, light in colour, and can be worked on normal rubber machinery. Its electrical insulating properties are excellent.
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| Đệm cao su dùng cao su tổng hợp | Butyl rubber has several disadvantages, especially its incompatibility with natural rubber and the main synthetics. In addition, butyl rubber has a strong affinity for foreign matter and must be carefully stored and screened before manufacture. Finally, it stiffens at low temperatures.
The polymerization of isobutylene is carried out at -95 C (-139 F), with aluminum chloride as a catalyst. Isobutylene and the desired proportion of isoprene are fed continuously into a medium of methyl chloride. After antioxidant is added, crumbs of butyl rubber form directly, without any latex stage. Zinc stearate (to prevent agglomeration, or formation of clumps of butyl rubber) also goes into the mixture. Excess reactants are recovered and re-used.
Because of its excellent air retention butyl rubber quickly took over from natural rubber for inner tubes in all but the largest sizes. Butyl rubber also plays an important part in the inner liners of tubeless tires. Despite excellent road-holding properties under wet conditions, and quiet, comfortable riding qualities, all-butyl tires have not proved commercially successful because of their poor tread durability. Butyl rubber, however, is used for many automobile components, such as window strips, because of its excellent resistance to oxidation. In its resistance to heat, butyl rubber also plays an indispensable part in tire manufacture, forming the container for the hot water or steam required to vulcanize the inside of tires.
Tài liệu được trích lại từ:
http://www.uv.es/EBRIT/macro/macro_5007_25_7.html
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