Three EPDM is ethylene, propylene and non conjugated diene copolymer three yuan, began commercial production in 1963. The consumption of the world is 800 thousand tons per year. The most important characteristic of EPDM is its superior resistance to oxidation, ozone resistance and resistance to corrosion. Because the three EPDM belongs to the poly (PA66) hydrocarbon family, it has excellent curing characteristics. Among all the rubber, EPDM has the lowest specific gravity. It can absorb a large amount of filler and oil and has little effect. So the rubber compound with low cost can be produced.
Molecular structure and properties
Three yuan is three yuan of copolymer of ethylene, propylene and non conjugated diene. It has a special structure, only one of the two keys to copolymerization, unsaturated double bond is mainly used as the chain. Another unsaturated polymer chain will not become a side chain. The main polymer chain three yuan is fully saturated. This characteristic makes three yuan can resist heat, light, oxygen, especially ozone. Three yuan is essentially non-polar, resistant to polar solvents and chemicals, low water absorption, good insulating properties.
In three yuan in the production process, by changing the number of the three monomer, ethylene propylene ratio, molecular weight and its distribution and curing method can adjust its characteristics.
EPDMSelection of EPDM third monomer
The monomer of the type 32 olefin is produced by copolymerization of ethylene and propylene in the polymer, so as to realize the vulcanization. Third the choice of monomer must meet the following requirements:
Up to two keys: one can be polymerized, one can be vulcanized
The reaction is similar to the two basic monomers.
Random aggregation of primary key generates uniform distribution
Sufficient volatility to facilitate removal of the polymer from the polymer
The final cure rate of the polymer is suitable
The industrial production of ethylene propylene rubber with third three yuan only the following three kinds of monomer:
1, 4- (HD)
(such a single body is currently only the United States Pont Du company use)
Effect of the type and content of the type of the polymer on the properties of the polymer
Three yuan in the production is mainly used ENB and DCPD.
Three yuan is the most widely used in ENB, it is DCPD vulcanized much faster. Under the same polymerization conditions, the nature of the third monomers affects the long chain branching, and the following order is increasing: EPM<EPDM (ENB) <EPDM (DCPD)