Low-pressure polyethylene is produced from purified ethylene, and triethylaluminium and titanium tetrachloride act as the organometallic catalyst.
To obtain polyethylene in the domestic industry, several technological options are used that differ in the type of structure, reactor capacity, and methods of washing polyethylene from the catalyst used.
Technology
Most often, three consecutive operations are carried out: polymerization of ethylene, the process of purifying it from the catalyst and final drying. After mixing the solutions of triethylaluminum and titanium tetrachloride, cyclohexal and gasoline are added to them. A two percent solution heated to 50 ° C is fed into the reactor, where ethylene is added through the airlift system. Stirring the mass promotes partial polymerization of ethylene into polyethylene.
To remove the catalyst from the polymer, the resulting decomposition products are filtered off and dissolved. In a centrifuge, polyethylene is washed off the catalyst using methyl alcohol.
After washing, low-pressure polyethylene is squeezed out, and substances are added to it to improve the quality. For clarification, a stabilizer, ethylene glycol and sodium nitrophosphate are used, and wax is used to make it more shiny.
Finally, the polyethylene is dried and granulated. Low-pressure polyethylene is available in the form of granules and powder.
Pipes made of low pressure polyethylene
They are used for installation of gas, sewer and water systems.
Pipes are manufactured using continuous extrusion methods. The raw material for the production is polyethylene in granules.
Economically developed countries use such pipes in almost all systems.
HDPE pipes do not adversely affect water quality, since rust does not form on the inner walls and mineral salts are not collected.
Low-pressure polyethylene has found application in sewer systems, as it is resistant to aggressive substances and high temperatures.
Gas pipes also do not collapse and do not lose operational properties for a long time.
Durability is the main quality of HDPE pipes. They are impact resistant, do not rot and do not rust, and do not crack under the influence of high and
low temperatures. Their service life is several decades.
High pressure polyethylene is relatively soft and elastic. Its material has a relatively sparse arrangement of molecules, which, first of all, affects its density. A wide range of films is produced from LDPE. They are of very high quality, and for the packaging material the best option, perhaps, can not be found. It retains and maintains a set of positive properties even at temperatures reaching sixty degrees. The qualitative characteristics of such polyethylene do not change under the influence of chemicals. It is able to reliably isolate products from moisture and water vapor.