Cao su butyl là loại cao su tổng hợp khá thông dụng, nhưng lượng dùng thấp hơn các loại cao su tổng hợp khác như NBR, SBR, EPDM. Cao su butyl được sử dụng chủ yếu trong các ứng dụng yêu cầu các tính chất đặc trưng của nó như tính không thấm khí, khả năng hấp thu năng lượng cơ học cao. Phần tài liệu sau trình bày chung về tính chất và ứng dụng của cao su butyl.

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The single outstanding physical property of butyl rubber is its impermeability. It does not permit gases like hydrogen or air to diffuse through it nearly as rapidly as ordinary rubber does, and it has excellent resistance to the aging action of air. These properties make butyl rubber valuable in the production of life jackets (inflatable type), life rafts, and inner tubes for tires.

At room temperature, the resiliency of butyl rubber is poor, but as the temperature increases, the resiliency increases. At elevated temperatures, butyl rubber exhibits good resiliency. Its abrasion resistance, tear resistance, tensile strength, and adhesion to fabrics and metals is good. Butyl rubber has a maximum continuous service temperature of 250-350°F (120-150°C) with good resistance to heat aging. Its electrical properties are generally good but not outstanding in any one category. The flame resistance of butyl rubber is poor.

The polymer has excellent flexibility but very low resilience due to its molecular structure. As a result, it absorbs a great deal of any mechanical energy that is put into it. This energy absorption is responsible for butyl rubber’s vibration-damping properties, which are maintained over a broad temperature range. Consequently, butyl rubber is an excellent choice where high vibration damping is required. This property is useful in automobile body mounts and suspension bumpers.

Table 4.15 lists the physical and mechanical properties of butyl rubber.

There are two commercially available halogenated butyl rubber derivatives bromobutyl (BIIR) and chlorobutyl (CIIR). The halogen atoms are incorporated into the polymer on the isoprene units. These compounds have chemical properties that permit the polymers to be covulcanized with other elastomers more readily than IIR. The end-use properties and applications are similar to those for IIR. A typical application is the cover for air conditioning hoses.

Chlorobutyl (CIIR) rubbers have a maximum operating temperature of 300°F (150°C) and can be operated as low as -30°F (-34°C). The other physical and mechanical properties are similar to those of butyl rubber.

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Trích đăng từ sách Mechanical and Corrosion-Resistant Properties of Plastics and Elastomers, Philip A. Schweitzer, CRC Press, 2000, trang 295 – 299

(vtp-vlab-caosuviet)