EPDM reclaimed rubber has excellent high and low temperature resistance, aging resistance and ozone resistance. It can be used alone or in combination with EPDM and butyl rubber to produce various rubber products, such as rubber sealing strips, sealing rings, rubber hoses, Waterstops, conveyor belts, etc., reducing the cost of raw materials. When using EPDM reclaimed rubber to produce rubber products with high strength requirements, the following three aspects can be considered when designing the formula.
1. EPDM reclaimed rubber and raw rubber are used together
When using ethylene propylene diene monomer (EPDM) recycled rubber to produce high-strength rubber products, the strength of the finished products can be effectively improved by mixing with an appropriate amount of EPDM. In the actual production, it is very beneficial to choose the EPDM with high molecular weight and wide molecular weight distribution to improve the strength. Due to the super high molecular weight of macromolecules, oil extended EPDM raw rubber is an effective way to obtain high strength of low hardness compound by replacing a large number of external oiling of ordinary EPDM with oil extended EPDM raw rubber.
2. rational use of rubber reinforcement
The use of reinforcing agent is an effective way to improve the strength of EPDM reclaimed rubber products. Carbon black or silica with high reinforcing property such as N220 and N330 can be used as reinforcing agent for high strength EPDM reclaimed rubber products; The strength of the compound generally increases with the increase of the amount of carbon black, and the performance of the compound will deteriorate if the amount of carbon black continues to increase after reaching the maximum; The amount of carbon black in EPDM reclaimed rubber products is generally controlled at 30-100 phr.
3. reasonably design the vulcanization system of EPDM reclaimed rubber
In the production of high-strength rubber products from ethylene propylene diene monomer reclaimed rubber, the strength of the compound will be affected by insufficient vulcanization or excessive crosslinking. The appropriate crosslinking density is very important to maintain the good physical and mechanical properties of the compound.
From the aspect of curing agent, although the polysulfide crosslinked bond formed by the ordinary sulfur curing system has poor heat resistance, its bond length is large, its mobility is strong, and it has the ability to slide, fracture and regenerate e5lyy429 along the hydrocarbon main chain, so the stress is easier to be dispersed and redistributed, and the compound has high tensile strength and tear strength. The effective vulcanization system or sulfur donor system forms short single sulfur bonds and double sulfur bonds, while the peroxide vulcanization system forms shorter C-C cross-linking bonds. Although this short cross-linking bond has good chemical stability, it has poor mobility, making it more difficult to disperse the stress. As a result, the tensile strength of the compound is generally low, and the tear resistance is generally poor. EPDM reclaimed rubber vulcanizates usually have high tensile strength, tear strength and fatigue resistance. When zinc methacrylate, zinc acrylate and other metal salt activators were mixed in the peroxide cured ethylene propylene diene monomer recycled rubber compound, the tensile strength, tear strength and flexure resistance of the compound were better.
To improve the strength of EPDM recycled rubber products, it is not only necessary to take measures to improve the strength of the compound, but also need to comprehensively consider the factors such as cost, processing performance, and the impact on other physical properties. EPDM compound for microwave continuous vulcanization was prepared by using ethylene propylene diene monomer (EPDM) reclaimed rubber, and good process properties could be obtained by filling a large amount of carbon black with medium reinforcement; In order to maintain good low-temperature elasticity and vulcanizate strength under atmospheric pressure, it is mostly used with ethylene propylene diene monomer with high ethylene content.
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