The difference between PET and PETG (1)

PET: Poly(ethylene terephthalate) English: Poly(ethylene terephthalate)

PETG: cyclohexanediol (copolyester) English: Polyethylene Terephthalate (PETG)

Compared with PET, the biggest feature of PETG is that PETG conforms to the concept of environmental protection and food FDA certification. PETG is currently more and more concerned about related products at home and abroad.

PET polyethylene terephthalate This polycondensate is mainly used in food packaging films and textile fibers and other applications. Now, its use as a packaging material is increasing, not only in soda drink bottles, but also in amorphous PET (APET) and crystalline PET (CPET) cans and dishes. Over the past five years, engineering-grade PET and copolyester, as new polymer products, have been used in engineered and specialty packaging materials, respectively.

The successful application of PET in soda beverage packaging materials is due to its toughness and transparency, orientation ability, excellent economic value and the development of high-speed bottle processing technology. PET beverage cans are lightweight, shatter-resistant, reusable, and airtight. A full 2-liter PET beverage bottle is 24% lighter than a comparable glass bottle; an empty bottle weighs 1/10 the same size glass bottle. It saves labor, energy and costs in all links from the producer to the consumer.

Chemistry and Properties

PET for beverage bottles is produced from terephthalic acid (TPA) obtained by the oxidation of paraxylene. Terephthalic acid is purified or reacted with methanol to form dimethyl terephthalate (DMT), or further oxidized to form pure terephthalic acid (PTA). Another basic raw material for PET is ethane, which is converted into ethylene glycol (EG) by reaction. PET is a polycondensate formed by the continuous polymerization of DMT (or PTA) and EG in the molten state, and then obtains large crystallites, final molecular weight, and intrinsic viscosity in the solid-state polymerization process. This solid state process also keeps the ethanol content of the polymer sufficiently low.

General commercial PET resin melts at about 480F ( ), but high crystalline PET has a melting point of about 520 F ( ).

Oriented crystalline PET has excellent strength. Toughness and transparency, and resistance to weak acids and bases and many solvents.