PET containers made of polyethylene terephthalate (PET, PET)
Polyethylene terephthalate or PET, PET — polymer, which is the most profitable raw material for the manufacture of packaging materials, including a variety of containers. It is familiar to many consumers under various names — polyester, terylene, melinex, dacron, lavsan, mylar. As a rule, all these substances are almost no different from each other — the difference is only in the country of origin. In the countries of the USSR, polyethylene terephthalate was given the name Lavsan — in honor of the Laboratory of Macromolecular Compounds of the Academy of Sciences. It was here that the substance was successfully synthesized in the late 40s.
The abbreviation PET is most often used as an abbreviation for polyethylene terephthalate dishes, and for products made from it, the abbreviation PET containers.
Pros of using PET for container production
On an industrial scale, polyethylene terephthalate began to be used due to its characteristics:
- High strength — the material can withstand numerous deformations and shock loading;
- Plasticity — in the production of polyethylene terephthalate is of high value due to its ease of processing;
- Inertness — polyethylene terephthalate is resistant to weak acids, alkalis, solutions, so its packaging is suitable for storing food, household chemicals, cosmetics;
- Insolubility in water — the polymer does not react with water;
- Dielectric properties — the substance does not conduct current and is often used as an insulating material for various components;
- Potential for recycling — polymer packaging and containers can be completely recycled;
- Human Safety — According to ILSI research, PET containers do not react with food, water and air and do not release toxic substances into the environment.
This material looks like an amorphous transparent substance. The substance is able to change shape under the influence of temperature, during crystallization it acquires a stable solid form and a matte shade, lends itself to coloring and metallization. For the production of plastic containers, it comes in the form of granulate, which is a universal raw material. In this form, polyethylene terephthalate is suitable for various types of equipment. The listed properties of the material make it an indispensable raw material for the production of packaging materials, ropes, twine, preforms for bottles and cans, and other containers.
Intrinsic viscosity of PET is in the range of 0.795-0.815 dl/g, while preform casting uses a substance with the maximum values of this parameter. An increase in this characteristic reduces the rate of polymer crystallization. This also results in high strength and wear resistance of PET along with dielectric properties.
The material is resistant to impact loads, tensile and bending deformations. It retains all these properties at temperatures from -40 to +60℃.
Low coefficient of friction
This material is wear resistant. Due to the low coefficient of friction, minimal creep combined with high elasticity, PET is suitable for the manufacture of almost any container. At the same time, products made from it can be used in the temperature range from -60 to 170℃.
The appearance and ability to transmit light (up to 90%) make PET look like polycarbonate and acrylic — transparent plexiglass. At the same time, PET has a much greater impact strength — 10 times more than acrylic.
|Main characteristics of polyethylene terephthalate:|
|Thermal conductivity:||0.14 W/(m·K).|
|Compressibility (melt):||99·106 MPa|
|Elongation at break:||12-55%|
|Glass transition temperature of amorphous polyethylene terephthalate:||67°C|
|Glass transition temperature of crystalline polyethylene terephthalate:||81°C|
|Refractive index (Na line) of amorphous polyethylene terephthalate:||1,576|
|Refractive index (Na line) of crystalline polyethylene terephthalate:||1,640|
|Tensile Strength:||172 MPa|
|Tensile modulus:||1.41*104 MPa|
|Permissible residual moisture:||0.02%|
|Frost resistance:||up to -60°C|