Cao su tổng hợp SBR được phát triển trong chiến tranh thế giới II do sự thiếu hụt của cao su thiên nhiên. Sự so sánh tính chất cơ lý của cao su thiên nhiên và cao su SBR được trình bày sau đây.

In general, Buna-S is very similar to natural rubber although some of its physical and mechanical properties are inferior. It is lacking in tensile strength, elongation, resilience, hot tear, and hysteresis. These disadvantages are offset somewhat by its low cost, cleanliness, slightly better heat-aging properties, slightly better wear than natural rubber for passenger tires, and availability at a stable price. The electrical properties of SBR are generally good but are not outstanding in any one area.

Because of these shortcomings, there are many variations and blends of NR-SBR. Basic is the ratio of butadiene to styrene, temperature of polymerization, and type of chemicals used during polymerization. The NR-SBR blends must be properly formulated to achieve the correct balance of properties. SBR is superior to NR in several of its processing properties. It also has excellent abrasion resistance and resistance to hydraulic brake fluid.

Molded SBR parts have a strong tendency to bloom due to the presence of added stabilizers. The bloom creates an unsightly appearance and can cause migration staining in contact with paint. Consequently, SBR is not generally used in readily visible locations or in contact with painted surfaces.

Buna-S has a maximum operating temperature of 175°F (80oC), which is not exceptional. At reduced temperatures below 0oF, Buna-S products are more flexible than those produced from natural rubber.

Butadiene-styrene rubber has poor flame resistance and will support combustion.

Trích đăng từ sách Mechanical and Corrosion-Resistant Properties of Plastics and Elastomers, Philip A. Schweitzer, CRC Press, 2000, trang 289 – 291


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