What is the essential difference between natural rubber and three yuan ethylene propylene rubber?
Vulcanized natural rubber elastic rubber and its crosslinking density is not too high, the elasticity is high. For example, in the range of 0-100 DEG C, elasticres at 50-85 DEG C, the elastic modulus of steel is only 1/3000, the tensile elongation is up to 1000%, to 350%, after retraction of permanent deformation is only 15%, a higher elasticity of natural rubber in the general rubber after polybutadiene rubber.
The strength of natural rubber in the elastic material, natural rubber, rubber, rubber, vulcanized rubber with higher intensity. The tensile strength of uncured rubber is called Green strength, and the Green strength of natural rubber is up to 1.4~2.5Mpa. The proper Green strength is necessary for rubber processing and forming. The tear strength of natural rubber is also higher, up to 98kN/m, and its abrasion resistance is better. The reason for the high mechanical strength of natural rubber is that it is self reinforcing rubber. When stretched, the macromolecule chains tend to form crystals in the direction of stress.
The glass transition temperature of natural rubber is -72 Deg. C, plastic flow temperature is 130 degrees centigrade, start decomposition temperature is 200 degrees centigrade, intense decomposition temperature of 270 DEG C. When natural rubber is vulcanized, its Tg rises, and no more viscous flow occurs.
The main use of natural rubber natural rubber because of its insulation, plasticity, water vapor barrier, tensile and wear characteristics of strong elasticity and good, widely used in industry, agriculture, national defense, traffic, transportation, machinery manufacturing, medical and health fields and daily life, such as transportation with the tire industry; with the transport belt, transmission belt, sealing rings; medical gloves, transfusion tube; used in the daily life of the shoes, raincoats, warm water bag are rubber as the main raw materials manufacturing, defense on the use of aircraft, artillery, tanks, and cutting-edge technology in the field of rockets, satellites, spacecraft, space shuttle requires a large amount of rubber parts.
The electric property of natural rubber is a kind of non polar material, and it is a better insulating material. When the natural rubber vulcanization after the introduction of polarity factors, such as sulfur, accelerator, so that insulation performance.The dielectric properties of natural rubber are a nonpolar substance that is soluble in non-polar solvents and non-polar oils. Natural rubber is not resistant to cyclohexane, gasoline, benzene and other media, non vulcanized rubber can be dissolved in the above medium, vulcanized rubber swelling. Natural rubber insoluble in polar acetone, ethanol, more insoluble in water, resistant to 10% hydrofluoric acid, 20% hydrochloric acid, 30% sulfuric acid, 50% sodium hydroxide and so on.
