Rubber Seal Performance Comparison
(1) the natural properties of rubber
Usually we are talking about natural rubber, is from the rubber tree collection of natural latex, through the solidification, drying and other processing processes made of solid. Natural rubber is a poly (isoprene) as the main component of the natural polymer compounds, the formula is (C5H8) n, the rubber hydrocarbon (polyisoprene) content of 90% or more, also contains a small amount of protein, fatty acids , Sugar and ash and so on.
Physical properties of natural rubber. Natural rubber at room temperature with high elasticity, slightly plastic, with very good mechanical strength, low loss of hysteresis, in a number of deformation when the heat is low, so its resistance to flexability is also very good, and because it is non-polar Rubber, so electrical insulation performance is good.
Natural rubber chemical properties. Because there are unsaturated double bonds, natural rubber is a strong chemical reaction material, light, heat, ozone, radiation, flexing deformation and copper, manganese and other metals can promote the aging of rubber, intolerant aging is natural rubber Of the natural weakness, but added antioxidant natural rubber, sometimes exposed to sunlight in the sun for two months still can not see much change in the warehouse after three years of storage can still be used as usual.
Natural rubber - resistant properties. Natural rubber has a good alkali resistance, but not strong acid. Since natural rubber is a non-polar rubber, it is resistant to some polar solvents and swells in non-polar solvents. Therefore, its resistance to oil and solvent resistance is poor. Generally speaking, hydrocarbons, halogenated hydrocarbons, , Ethers, higher ketones and higher fatty acids have a dissolution effect on natural rubber, but their solubility is affected by the degree of plasticity, while low-grade ketones, lower-grade vinegar and alcohols are non-solvents for natural rubber.
(2) Variety classification and quality standards
Natural rubber can be divided into two categories according to the form: solid natural rubber (film and granule) and concentrated latex. In daily use, solid natural rubber accounted for the vast majority of the proportion.
Film according to the manufacturing process and the appearance of different, can be divided into smoke tablets plastic, air-dried film, white wrinkles, brown wrinkles and so on. Smoke is the most representative of the natural rubber varieties, has been a large amount of large, widely used in a plastic species, smoke tablets generally according to the shape to grading, divided into premium, first, second, three, four , Five and so on a total of six, less than five are listed as outside the plastic.
The physical and chemical properties include the impurity content, the plastic initial value, the plastic retention rate, the nitrogen content, the volatile matter content, the ash content and the color index, and so on. The physical and chemical properties of the granules are as follows: Item, which is the dominant content of impurity content, according to the number of impurities divided into 5L, 5,10,20 and 50, a total of five levels.
(C) the main use of rubber
Because natural rubber has the above series of physical and chemical characteristics, especially its excellent resilience, insulation, water and plasticity and other characteristics, and after appropriate treatment also has oil, acid, alkali, heat, cold, pressure , Wear and other valuable properties, so with a wide range of uses. Such as daily life with the rain boots, warm water bags, elastic band; medical and health industry used in the surgeon gloves, blood vessels; transport with a variety of tires; industrial use of the conveyor belt, conveyor belt, acid and alkali gloves; Agricultural use of the irrigation and drainage hose, ammonia bag; weather measurement with the sounding balloon; scientific test with the seal, shock equipment; defense on the use of aircraft, tanks, artillery, gas masks; or even rockets, artificial earth satellites and spacecraft Sophisticated scientific and technological products indispensable raw materials. At present, the world part or completely made of natural rubber has reached more than 70,000 kinds of items.
(NBR) from butadiene and acrylonitrile emulsion polymerization obtained by the copolymer, said butadiene - acrylonitrile rubber, referred to as nitrile rubber. Its content is an important indicator of the performance of nitrile rubber. And known for excellent oil resistance. Oil resistance is the best, non-polar and weak polar oil is basically not swell.