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Property oF PET

Property profile of polyethylene terephthalate - PET

Jingyi Shi,*,†,
Junling Huang,*, ‡,

Background

On the application page, PET is widely applied in clothing, the package for liquids and foods, and making the film. In order to understand PET better, especially the application page, we will talk about several properties of PET corresponding to the application. We can browse this page in the corresponding application and vice versa.

QMES Academic, this issue

Abstract

This page is the property profile of PET, including general properties, physical properties, chemical properties, mechanical properties, electrical properties, thermal properties, optical properties, processability, and eco properties. These properties of PET basically is incredible, such as physical properties of low density and low oxygen transmission, chemical properties of non-toxic and good chemical resistance, mechanical properties of high Young's modulus and shear strength, electrical properties of high electrical resistivity, thermal properties of low thermal conductivity, optical properties of high diaphaneity, can be easily manufactured in processability and 100% recyclable in eco properties. In conclusion, PET has excellent properties.

General properties

Name

Polyethylene Terephthalate

Core Properties

Chemical formula: (C10H8O4)_n_.

Molar mass variable: 1) Density 1.38 g/cm3 (20 °C);

2)amorphous: 1.370 g/cm³; 3) Single-crystal: 1.455 g/cm³;

Melting point > 250 °C, 260 °C.

Boiling point > 350 °C. Solubility in water: practically insoluble.

Thermal conductivity: 0.15 to 0.24 W m⁻¹ K⁻¹.

Thermochemistry

Specific heat capacity (C): 1.0 kJ/(kg·K)

Table 1. Physical properties of PET [1-2] Table 2. Mechanical properties of PET [1-2]

1.png.3 2.png.1

Physical properties

PET is a colorless, semi-crystalline resin in a natural state. The low density of PET leads to the lightweight property, which is one of the reasons that PET is a suitable raw material of portable plastic bottles. The low surface roughness means that the surface of PET products smooth enough to be easy to disinfect and clean. The low oxygen transmission rate indicates that PET is a good gas and fair moisture barrier, as well as a good barrier to alcohol and solvents. Hence, PET bottles are widely used as containers for carbonated drinks to prevent the loss of CO₂ gases inside the drinks.

Mechanical properties

The Young' s modulus, shear modulus, shear strength, yield strength and tensile strength of PET all are high, which makes PET bottles impact-resistant to avoid damage and deformation of bottles during transportation or sales.

Table 3. Chemical properties of PET [1-2] Table 4. Electrical properties of PET [1-2]

3.png.1 4.png.1

Chemical properties

PET is non-toxic and does not react with water or food, so it is safe to be used for consumable packaging. PET has good chemical resistance to many chemicals such as alcohols, oils, diluted acids, and halogens, except for alkalis, which means PET has high chemical stability as well as corrosion resistance to avoid reaction with food or drink inside the PET package.

Electrical properties

The electrical resistivity of PET is 5×10⁶~ 1×10¹⁸. High electrical resistivity means that PET is a good electrical insulator, which makes it a suitable material to manufacture electronic insulation parts, such as connectors and shells of capacitor and transformer.

Table 5. Thermal properties of PET [1-2] Table 6. Optical and eco properties of PET [1-2]

5.png.1 6.png.4

Thermal properties

The thermal conductivity of PET is in the region of 0.015~0.290 W/m-K. The low thermal conductivity indicates that PET performs well as a thermal insulator, moreover, the melting temperature is quite high, which can be applied in making the handle of a pot or other heat-insulating parts.

Optical and eco properties

PET is usually a transparent material. Clear PET products can be produced by rapidly cooling molten polymer below T_g (glass transition temperature) to form an amorphous solid. PET products are 100% recyclable and are the most recycled plastic worldwide. PET bottles can be recycled into a new bottle again and again. Recycled PET fiber is widely used to make carpets or be spun into fiber filling for pillows and quilts. It can also be used to make cloth or jackets, or reappear in the form of plastic bottles.

References

[1] Information about PP, accessed on 07/06/2020, from <https://www.nature.com/articles/pj200880>

[2] Information about PP, accessed on 07/06/2020, from <http://www.matweb.com/search/DataSheet.>

PET（Polyethylene terephthalate）

PET（Polyethylene terephthalate）

Property Profile (PP)

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