Cao su tổng hợp được phát minh để cải thiện các khuyết điểm của cao su thiên nhiên, đáp ứng nhiều ứng dụng thực tế khắc nghiệt. Cao su chloroprene (neoprene hoặc CR) là một trong những loại cao su tổng hợp thông dụng. Tính chất hóa lý chung của cao su chloroprene được trình bày sau đây.

The properties discussed here are attainable with neoprene but may not necessarily be incorporated into every neoprene product. Nor will every neoprene product perform the same in all environments. The reason for this variation is compounding. By selective addition and/or deletion of specific ingredients during compounding, specific properties can be enhanced or reduced to provide the neoprene formulation best suited for the application. A neoprene compound can be produced that will provide whichever of the properties discussed are desired. When the hardness of neoprene is above 55 Shore A, its resilience exceeds that of natural rubber by approximately 5%. At hardnesses below 50 Shore A, its resilience is not as good as that of natural rubber, even though its resilience is measured at 75%, which is a high value. Because of its high resilience, neoprene products have low hysteresis and a minimum heat buildup during dynamic operations.

Solid neoprene products can be ignited by an open flame but will stop burning when the flame is removed. Because of its chlorine content, neoprene is more resistant to burning than exclusively hydrocarbon elastomers. Natural rubber and many of the other synthetic elastomers will continue to burn once ignited, even if the flame is removed. In an actual fire situation, neoprene will burn. Although compounding can improve the flame resistance of neoprene, it cannot make it immune to burning.

Compared to natural rubber, neoprene is relatively impermeable to gases. Table 4.9 lists typical permeability constants. Because of this impermeability, neoprene can be used to seal against Freon blowing agents, propane, butane, and other gases.

Neoprene is used in many electrical applications, although its dielectric characteristics limit its use as an insulation to low voltage (600V) and low frequency (60Hz). Because of its high degree of resistance to indoor and outdoor aging and its resistance to weathering, neoprene is often used as a protective outer jacket to insulation at all voltages. It is also immune to high-voltage corona discharge effects that cause severe surface cutting in many types of elastomers.

Trích đăng từ sách Mechanical and Corrosion-Resistant Properties of Plastics and Elastomers, Philip A. Schweitzer, CRC Press, 2000, trang 281 – 282


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