1. Types and characteristics of rubber
(I) general purpose rubber
⒈ Natural rubber NR: prepared from latex of rubber tree Trefoil. Its basic chemical composition is cis-polyisoprene, which is a polymer of isoprene.
It is a raw material for making tape, rubber hose and rubber shoes. It is suitable for making shock absorbing parts, and it is used in liquid products with hydroxide such as automobile brake oil and ethanol.
Advantages: Good wear resistance, high elasticity, tensile strength and elongation, acid and alkali resistance, good comprehensive performance.
Disadvantages: Heat resistant, oil resistant (can tolerate vegetable oil), easy to expand and dissolve in mineral oil or gasoline, alkali resistant but not resistant to strong acids. It is easy to age in the air and becomes sticky in the heat.
⒉ Isoprene rubber IR: Full name is Cis-1, 4-polyisoprene rubber, high order synthetic rubber obtained from isoprene, produced by solution polymerization method. Because its structure and properties are similar to natural rubber, it is also called synthetic natural rubber.
Can replace natural rubber manufacturing truck tires and off-road tires, can also be used to produce a variety of rubber products.
Advantages: Like natural rubber, it has good elasticity and wear resistance, excellent heat resistance and good chemical stability, mass uniformity and processing properties are better than natural rubber.
Disadvantages: Raw rubber (before processing) strength is significantly lower than natural rubber.
⒊ Styrene butadiene rubber SBR made from copolymerization of butadiene and styrene. Is the largest production of general synthetic rubber, according to the production method is divided into emulsion polymerization styrene butadiene rubber, solution polymerization styrene butadiene rubber and thermoplastic rubber (SBR).
Widely used in tire industry, shoes industry, cloth industry and conveyor belt industry.
Advantages: Low cost non-oil resistant material, good water resistance, hardness below 70 with good elasticity, high hardness with poor compressibility. Compared with natural rubber, it has uniform quality, less foreign matter, better wear resistance and aging resistance. Its comprehensive performance and chemical stability are good, and it can be mixed with natural rubber.
Disadvantages: Mechanical strength is weak. It is not recommended to use strong acids, ozone, oils, oil esters, fats and most hydrocarbons.
The full name of butadiene rubber is cis-1, 4-polybutadiene rubber, which is prepared by solution polymerization of butadiene.
Most of them are used in the production of tires, and a small part is used in the manufacture of cold resistant products, buffer materials and tape, rubber shoes.
Advantages: vulcanized butadiene rubber has excellent cold resistance, wear resistance and elasticity, less heating under dynamic load, good aging resistance, easy to use with natural rubber, neoprene rubber, nitrile rubber and so on.
Disadvantages: poor tear resistance, poor skid resistance.
⒌ chloroprene CR: made of chloroprene as the main raw material, through homopolymerization or a small number of other monomers. Vulcanized rubber elastic wear resistance is good, the formula does not contain sulfur, so it is very easy to make, has a particularly good weather resistance, not afraid of intense distortion, not afraid of refrigerant, dilute acid resistance, silicone ester lubricating oil resistance, the general use of temperature range is -50-150 ℃.
Chloroprene rubber is widely used, such as the production of transport belt and transmission belt, wire, cable coating material, the manufacture of oil resistant hose, gasket and chemical corrosion resistant equipment lining. Make a variety of direct contact with the atmosphere, sunlight, ozone parts. Suitable for all kinds of rubber products with fire resistance and chemical corrosion resistance. Do not recommend the use of strong acids, nitrohydrocarbons, esters, chloroform and ketone chemicals, R12 refrigerant resistant seals, rubber parts or seals on household appliances.
Advantages: It has good comprehensive properties, such as high tensile strength, water resistance, oil resistance, fire resistance, heat resistance, light resistance, aging resistance, oxidation resistance and ozone resistance. Good elasticity and compression deformation, with anti animal and vegetable oil characteristics, will not be affected by neutral chemicals fat, grease, a variety of oils, solvents and physical properties, with fire resistance. High chemical stability.
Disadvantages: high density, easy crystallization and hardening at room temperature, bad storage, electrical insulation performance, cold resistance is poor, easy crystallization and hardening at low temperature, raw rubber is unstable in storage. Phosphate ester type hydraulic oil is not resistant. The expansion of mineral oil with low aniline point is large.
EPDM: to make vinyl and propylene as main raw material, good chemical stability, wear resistance, elasticity, oil resistance and styrene butadiene rubber. EPDM is formed by introducing a small amount of the third component with double chain into the EP main chain and adding sulfur. The general use temperature is 50-150 ℃ below zero. Excellent resistance to polar solvents such as alcohol and ketone. Very wide range of uses, can be used as tire tire side, rubber strip and inner tube and auto parts, as wire, cable cover and high voltage, ultra-high voltage insulation material. Manufacture rubber shoes, sanitary products and other light products. Can be filled with a large number of oil and carbon black, the product price is low, commonly used for high temperature water steam environment, sanitary equipment sealing parts or parts. Rubber parts in a braking system. A seal in a radiator (car water tank).
Advantages: Good weather resistance and ozone resistance, excellent water resistance and chemical resistance, alcohol and ketone can be used, high temperature vapor resistance, good permeability to gas. Heat resistance, aging resistance, ozone resistance, electrical insulation stability are very good,
Cons: Not recommended for food use or exposure to aromatic hydrocarbons.
Butyl rubber IIR: it is made by polymerization of isobutene and a small amount of isoprene. Because the movement of the three-dimensional obstacle molecule of methyl is less than that of other polymers, the general temperature range is 54-110 ℃ below zero.
Commonly used in automobile tire inner tube, leather bag, rubber paste paper, window frame rubber, steam hose, heat resistant conveyor belt, etc.
