Polyethylene terephthalate (PET) is a thermoplastic polymer from the polyester family that is produced by stepwise polymerization by the reaction between pure terephthalic acid (PTA) and monoethylene glycol (MEG). The glass transfer temperature of this polymer is about 80 ° C.
There is a lot of variation in the properties of this polymer, depending on the application and the orientation of the polymer chains. It will be 31.33 cm. Due to slow molecular motions, crystallization starts around 80 ° C and at 130 ° C its density increases by 1.37 gr / cm3. With proper orientation and heat application, the density also increases to 1.40 gr / cm3.
Polyethylene terephthalate is a polymer that is used in most countries to produce polyester fibers (70%), bottle resin (22%), film (6%) and engineering polyester resins (2%), but in Iran this polymer is more Used to make all kinds of drinking bottles. Due to the high resistance of these bottles against breakage, temperature and penetration of gases, having a low weight and cheap price compared to other packaging materials such as glass and metal, the production of plastic bottles from this resin has been widely used. As a result, used PET bottles enter the municipal waste stream.The high volume of these bottles in relation to the weight, which take up a lot of space during transportation and burial, and their very long decomposition in nature (about 300 years), has caused the problem of recycling these bottles, especially In recent years, it has attracted everyone’s attention.