What is PET and All about PET (Polyethylene Terephthalate)

Polyethylene Terephthalate (PET) is the world’s most recycling and safe plastic with recycling code number 1(One). Second World War is the major cause of plastic production and invention of new plastics. PET was invented by DuPont chemist in 1940. Natural resources were not enough to fulfil the needs of peoples. So scientist worked on synthetic resources. First use of PET was to make clothes and then in 1950 PET was extruded into thin sheet. This this sheet used in photo, video, X-ray and packaging films. In the early 1970s, the technology was developed to allow for the blow-stretch molding of PET into strong, lightweight and shatterproof bottles. In 1973, the PET bottle was patented and quickly gained market acceptance. In 1977, the first PET bottle was recycled.

How PET Plastic is made??

PET plastic is made by polycondensation process in which two chemicals, terephthalic acid and ethylene glycol react and PET and water are products. Water is removed and pure PET remains. For commercial scale there are two routes but above listed is most used.

Properties of PET Plastic

There are few clear plastics and PET in one of them while other plastics are PC, PMMA and Polystyrene.

PET has good barrier properties

High melting and glass transition temperature Tg (Tg above this temperature plastic starts softening).

High strength

High strength to weight ration

Can be filled at high temperature

Uses of PET in different fields

PET is used in various fields of life like

Packaging

Soft flexible Packaging

PET Films

BOPET Films

Containers and Bottles

PET Bottles for CSD (Carbonated soft drinks), Water, Home care products, Personal care products, Milk, and many more. PET containers are used store candies, and many others things.

Tire Industry

Cords made from high IV PET are used in tire industry.

IT Video and Audio Industry

Photo, audio video tapes are made from PET films

Medical Uses

Vacutainers and many other equipment are made from PET as it is safe material for medical and body touch.

Different Variations of PET

PET is used for packaging, cloths, carpets, and high strength cords the formula and structure of PET remains same for PET used in all these but there is only difference in IV (Intrinsic Viscosity). IV ranges for cloths or fiber are from .5 to .75 while for bottles it’s from .74 to .92 while to produce high strength cords to use in tires and other high strength required products PET IV rages from .9 to above 1.

Recycling of PET

PET can be recycle again and again from bottle to bottle or bottle to fiber. When PET is exposed to high heat for long time or processed at high temperature it degrades and IV lowers. So PET flakes from bottle crushing can be directly melt spun to fiber. If bottle to bottle conversion is required so regeneration of PET flakes are required. PET flakes are regenerated in a reactor (Solid state polymerization).