Thứ Tư, 28 tháng 8, 2013

Tính kháng hóa chất của cao su chloroprene (CR)

Cao su chloroprene (CR) là một loại cao su tổng hợp thông dụng. Nó có tính kháng dầu mỡ, dung môi hydrocarbon tốt, khắc phục khuyết điểm của cao su thiên nhiên. Ngoài ra, cao su chloroprene còn kháng được nhiều loại hóa chất khác như như axit, kiềm, muối, nước, giúp cho việc sử dụng loại cao su này linh hoạt, phù hợp với nhiều môi trường. Tính kháng hóa chất của cao su chloroprene được trình bày cụ thể bên dưới.
Neoprene’s resistance to attack from solvents, waxes, fats, oils, greases, and many other petroleum-based products is one of its outstanding properties. Excellent service is also experienced when it is in contact with aliphatic compounds (methyl and ethyl alcohols, ethylene glycols, etc.), aliphatic hydrocarbons, and most Freon refrigerants. A minimum amount of swelling and relatively little loss of strength occur when neoprene is in contact with these fluids.
When exposed to dilute mineral acids, inorganic salt solutions, or alkalies, neoprene products show little if any change in appearance or change in properties.
Chlorinated and aromatic hydrocarbons, organic esters, aromatic hydroxy compounds, and certain ketones have an adverse effect on neoprene, and consequently only limited serviceability can be expected with them. Highly oxidizing acid and salt solutions also cause surface deterioration and loss of strength. Included in this category are nitric acid and concentrated sulfuric acid.
Neoprene formulations can be produced that provide products with outstanding resistance to water absorption. These products can be used in continuous or periodic immersion in either freshwater or saltwater without any loss of properties.
Properly compounded neoprene can be buried underground successfully, since moisture, bacteria, and soil chemicals usually found in the earth have little effect on its properties. It is unaffected by soils saturated with seawater, chemicals, oils, gasolines, wastes, and other industrial byproducts.
Trích đăng từ sách Mechanical and Corrosion-Resistant Properties of Plastics and Elastomers, Philip A. Schweitzer, CRC Press, 2000, trang 284 – 285
(vtp-vlab-caosuviet)