Summary of rubber material types and performance parameters
The performance of rubber mainly depends on the type of raw rubber used and the different formulations of rubber materials.
Types of rubber:
1.1 Natural rubber (NR)
Natural rubber (NR) is a polymer of isoprene. It has excellent resilience, tensile strength, elongation, wear resistance, tear and compression permanent deformation performance superior to most synthetic rubbers. Suitable for making tires, shock absorbing parts, buffer ropes, and sealing parts. Not resistant to oil, poor weather, ozone, and oxygen resistance. The operating temperature range is -60~100 ℃.
1.2 Styrene butadiene rubber (SBR)
Styrene butadiene rubber (SBR) is a copolymer of butadiene and styrene. The butadiene styrene 10 containing 10% styrene has good cold resistance, while the butadiene styrene 30 containing 30% styrene has excellent wear resistance. Suitable for making tires and sealing parts, but the product has poor oil resistance and aging resistance. The temperature range for use is -60~120 ℃.
1.3 Butadiene rubber (BR)
Butadiene rubber (BR) is a polymer of butadiene. Commonly used butadiene rubber has good cold resistance, wear resistance, and rebound performance. Suitable for making products such as tires, sealing parts, shock absorption parts, tape, and hoses. The product is not resistant to oil and aging. The operating temperature range is -70~100 ℃.
1.4 Neoprene rubber (CR)
Chloroprene rubber (CR) is a chloroprene polymer that is weather resistant, ozone resistant, self extinguishing, and has oil resistance, second only to nitrile rubber. It has excellent tensile strength, elongation, and resilience, and has good adhesion to metals and fabrics. Suitable for making sealing rings and sealing profiles, rubber hoses, coatings, wire insulation layers, adhesive tapes, and preparing adhesives. The product is not resistant to synthetic diester lubricating oil and phosphate ester hydraulic oil. The operating temperature range is -35~130 ℃.
1.5 Nitrile rubber (NBR)
Nitrile rubber (NBR) is a copolymer of butadiene acrylonitrile. Generally, it contains 18%, 26%, or 40% acrylonitrile. The higher the content, the better the oil resistance, heat resistance, and wear resistance, but the opposite is true for cold resistance. Nitrile rubber containing carboxyl groups has better wear resistance, high temperature resistance, and oil resistance than nitrile rubber. Nitrile rubber is suitable for making various oil resistant sealing parts, membranes, rubber hoses, and soft oil tanks. The product is not resistant to weather, ozone aging, and phosphate ester hydraulic oil. The operating temperature range is -55~130 ℃.
1.6 Ethylene propylene rubber (EPM, EPDM)
Ethylene propylene rubber is a binary copolymer (EPM) of ethylene and propylene or a ternary copolymer (EPDM) of ethylene, propylene, and diene olefins. Weather resistant, ozone resistant, resistant to steam, phosphate hydraulic oil, acid, alkali, rocket fuel and oxidant, with excellent electrical insulation performance. Suitable for producing sealing parts, rubber hoses, aircraft, automotive door and window sealing profiles, adhesive tapes, and wire insulation layers for phosphate ester hydraulic oil systems. The product is not resistant to petroleum based oils. The operating temperature range is -60~150 ℃.
1.7 Butyl rubber (IIR)
Butyl rubber (IIR) is a copolymer of isobutylene and isoprene. Resistant to weather and ozone aging, phosphate ester hydraulic oil, acid, alkali, rocket fuel, and oxidants, with excellent dielectric and insulation properties, and minimal breathability. Suitable for making tire inner tubes, door and window sealing strips, sealing parts for phosphate ester hydraulic oil systems, rubber hoses, insulation layers for wires, adhesive tapes, and shock absorbers. The product is not resistant to petroleum based oils. The operating temperature range is -60~150 ℃.
1.8 Chlorosulfonated polyethylene rubber (CSM)
Chlorosulfonated polyethylene rubber (CSM) is resistant to weather and ozone aging, and its oil resistance increases with its chlorine content. It is acid and alkali resistant, suitable for making adhesive tapes, connecting sleeves for automotive air filters, radiator drainage pipes, sealing pads, cable sleeves, anti-corrosion coatings, and outer walls of soft oil tanks. The operating temperature range is -50~150 ℃.
1.9 Polyurethane rubber
It is a polyurethane. There are usually two types: polyester (AU) and polyether (EU). It has excellent tensile strength, tear strength, and wear resistance, excellent oil and ozone resistance, as well as resistance to atomic radiation. Suitable for making various shapes of sealing energy absorption devices, punching templates, vibration damping devices, mechanical support gaskets, flexible connections, anti wear coatings, friction power transmission devices, rubber rollers, etc. The operating temperature range is -60~80 ℃. It should not come into contact with esters, ketones, phosphate ester hydraulic oils, concentrated acids, alkalis, vapors, etc.
1.10 Polysulfide rubber (T)
There are two types of polysulfide alkane polymers: solid polysulfide rubber and liquid polysulfide rubber. Good oil resistance, weather aging resistance, low breathability, and excellent electrical insulation. Solid rubber is usually used in conjunction with nitrile rubber to manufacture sealing parts, hoses, and membranes for fuel systems. The usage temperature range is -50~100 ℃, and can reach 130 ℃ in a short period of time. Liquid adhesive is usually used to prepare sealing agents.
1.11 Chlorohydrin rubber
It is a polymer of epichlorohydrin hydrocarbons (CO), a binary copolymer of epichlorohydrin and ethylene oxide (ECO), or a ternary copolymer with a third monomer (epichlorohydrin) added. It has oil and ozone resistance, better heat resistance than adhesive, and less breathability. Suitable for making sealing gaskets and diaphragms.
1.12 Acrylate rubber (ACM)
Acrylate rubber (ACM) is a new type of special rubber developed internationally, with excellent properties such as heat resistance, oil resistance, cold resistance, and ozone resistance. According to needs, it can be used in combination with fluororubber, nitrile rubber, chlorosulfonated polyethylene, ethylene propylene diene rubber, etc. to achieve high temperature and oil resistance. Widely used in high-temperature oil seal materials for automobiles and military equipment, adhesives for container and pipeline lining, and building sealants, as well as outer sheaths for special wire and cable insulation and shock absorption products.
1.13 Silicone rubber
It is a polysiloxane. Usually there are dimethyl silicone rubber (MQ), methyl vinyl silicone rubber (MVQ), methyl phenyl silicone rubber (MPQ), methyl phenyl vinyl silicone rubber (MPVQ), etc. Silicone rubber has excellent heat resistance, cold resistance, and aging resistance, excellent insulation resistance and dielectric properties, good thermal conductivity, but poor strength and tear resistance, oil resistance, and high price. Generally suitable for making sealing rings, sealing profiles, oxygen corrugated pipes, diaphragms, shock absorbers, insulation materials, and insulation sponge rubber plates. The operating temperature range is -70~280 ℃.
1.14 Fluoroelastomer (FPM)
Commonly used are fluororubber 26 and fluororubber 246, the former being a copolymer of vinylidene fluoride and hexafluoropropene, while the latter is a copolymer of vinylidene fluoride, tetrafluoroethylene, and hexafluoropropene. Fluorine rubber has outstanding heat, oil, acid, and alkali resistance, excellent aging and electrical insulation properties, flame retardant, and low breathability. But the low-temperature performance is poor. The general usage temperature range is -40~250 ℃, and can reach 300 ℃ in a short period of time. Suitable for producing various sealing parts, rubber hoses, tapes, and fuel tanks that require heat and oil resistance, but the price is relatively expensive.
1.15 Fluorosilicone Rubber (MFQ)
It is a polysiloxane containing fluoroalkyl groups. Excellent oil resistance, chemical resistance, heat resistance, cold resistance, and aging resistance, but low strength and tear resistance, making it expensive. Suitable for making sealing rings and diaphragms for fuel, diester lubricants, and hydraulic oil systems. The operating temperature range is -65~250 ℃.
The main properties of vulcanized rubber:
2.1 Tensile properties
All rubber materials should first consider their properties, including tensile strength, constant elongation stress, elongation, elongation at break, and permanent deformation at break, as well as stress-strain curves. The tensile strength is the maximum tensile stress at which a specimen is stretched to fracture. The constant elongation stress (modulus) is the stress (modulus) reached at a specified elongation. Elongation is the deformation caused by tensile stress on a specimen, expressed as a percentage of the ratio of elongation increment to original length. The elongation at break is the elongation at which the sample is broken. Tensile permanent deformation is the residual deformation of the gauge length after tensile fracture.
It represents the ability of rubber to resist external pressure and is also the basic performance of all rubber materials. The hardness of rubber is to some extent related to other properties. For example, the higher the hardness of the rubber material, the higher its strength, lower its elongation, and better its wear resistance, while its low temperature resistance is poorer. High hardness rubber can resist compression damage under high pressure. Therefore, appropriate hardness should be selected based on the working characteristics of the parts. At present, Shore A (HS A) hardness tester is commonly used in China to measure the hardness of rubber, which is close to the international rubber hardness value.
2.3 Compression performance
Compression performance rubber seals are usually in a compressed state. Due to the viscoelasticity of rubber, after compression, the compressive stress will decrease over time, manifested as relaxation of compressive stress; After removing the pressure, the original shape cannot be restored, manifested as compression permanent deformation. In high-temperature oil media, these phenomena are more significant. They can affect the sealing performance of seals and are one of the important properties of sealing materials.
2.4 Low temperature performance
The low-temperature performance of rubber is usually represented by the following three methods. 1) The most commonly used is the brittle temperature, which refers to the highest temperature at which a specimen ruptures under a certain impact force at low temperatures. It can be used to compare the low-temperature performance of different rubber materials. However, due to the different working conditions and experimental conditions of rubber, the brittleness temperature of rubber does not indicate the minimum working temperature of rubber components, especially in oil media. 2) The low-temperature retraction temperature refers to stretching the test piece to a certain length at room temperature, then fixing it, rapidly cooling it below the freezing temperature, reaching temperature equilibrium, releasing the test piece, and heating it at a certain rate. Record the temperatures at which the test piece retracts 10%, 30%, 50%, and 70%, represented by TR10, TR30, TR50, and TR70, respectively. TR10 is generally used as the standard in material standards, which is close to the brittle temperature of rubber. 3) Cold resistance coefficient refers to the compression of a sample to a certain amount of deformation at room temperature, followed by freezing at a specified low temperature, and then unloading the load to allow it to recover at low temperature. The ratio of the recovery amount to the compression amount is called the compression cold resistance coefficient. The larger the coefficient, the better the cold resistance of rubber.
2.5 Oil resistance
Rubber in oil media (such as fuel, lubricating oil, hydraulic oil, etc.), especially at higher temperatures, can cause expansion, softening, and decrease strength and hardness. At the same time, plasticizers or soluble substances in rubber may be leached out by oil, resulting in weight reduction, volume reduction, and leakage. Therefore, the oil resistance of rubber is an important performance of rubber materials working in oil media. It is generally measured for changes in weight, volume, strength, elongation, and hardness after soaking in oil for a certain period of time at a certain temperature. Sometimes it can also be represented by the oil resistance coefficient, which is the ratio of the strength or elongation after immersion in the medium to the original strength or elongation.
2.6 Aging resistance
Rubber aging refers to the deterioration of its performance caused by factors such as oxygen (air), ozone, heat, light, moisture, and mechanical stress. The aging resistance of rubber can be determined through natural aging and artificial accelerated aging tests (such as thermal aging, humid thermal aging, ozone aging, etc.). The aging resistance can be expressed by the changes in strength, elongation, or hardness of the aged sample, or by the aging coefficient, which refers to the ratio of the tensile strength, elongation at break, or the product of the tensile strength and elongation at break of the aged sample to the original value, and is correspondingly called the aging coefficient calculated based on tensile strength (referred to as the aging coefficient calculated based on strength) The aging coefficient calculated based on elongation at break (referred to as the aging coefficient calculated based on elongation) or the aging coefficient calculated based on tensile product (referred to as the aging coefficient calculated based on tensile product).
Rubber related generation equipment: