Thepolyethyleneit is the most important addition polymer, it is produced from petroleum refining and is the first of the five chemical compounds synthesized in the greatest quantities in the United States. Thepolyethyleneit is widely used for the production of packaging and plastic materials.
What is a polymer?
We said thepolyethyleneit's a polymer, but what are we talking about? The word polymer comes from the Greekpoly and merosand literally means "many parts". THEpolymersthey are large molecules obtained by joining together many smaller molecules called "monomers". Thepolyethyleneit's athermoplastic polymerproduced starting from the monomer "ethylene" with the chemical formula C2H.4.
THEthermoplastic polymersas thepolyethylenethey become soft and then fluid when heated while they harden when cooled.
It is difficult to describe the properties of thepolyethylene: the polyethylene prepared in different temperature and catalysis conditions can include different properties dictated by different molecular structures, so we have thepolyethylenehigh and low density and thepolyethylenebranched.
- Polyethylene high density, polyethylene low density e polyethylene branched
High density polyethylene
When thepolyethyleneis produced in linear chains with high molecular weight that pack on each other (perhaps using chromium oxide as a catalyst), the so-calledhigh density polyethylene,a material whose density is 0.97 g / cm3. Thepolyethylenehigh density, indicated with the initials HDPE (high-density polyethylene)it is hard and resistant, it is a very popular plastic material for the production of rigid packaging such as bottles and bottles.
Low density polyethylene
Thepolyethyleneat low density it is produced from ethylene heated to 250 ° C and at high pressures. In these conditions, irregular branches are formed that do not allow the polyethylene chains to be packed together. The polyethylene low density, indicated with the initials LDPE (low-density polyethylene)it is softer and more flexible, which is why it is used for the production of soft packaging such as plastic bags and various packaging.
When the branched linear chains of thepolyethyleneare connected to each other in an orderly way, we speak ofpolyethylenebranched. Branched polyethylene is indicated by the abbreviation CLPE, an acronym forcross-linked polyethylene,we are talking about a material even more than high-density polyethylene. Often, plastic bottle caps are made of branched polyethylene.
- Polyethylene in industries
In the United States alone, over 7 million tons ofpolyethyleneintended for various industrial sectors, from the automotive to the packaging sector. Thepolyethyleneit is used to produce plastic bottles, plastic bags, films, toys, printed objects, electrical insulators, baby diapers….
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