Polyethylene Terephthalate Polyester ( PET, PETP ) - Properties and Applications - Supplier Data by Goodfellow

Topics Covered

Background

General Properties

Polyethylene Terephthalate Films

Applications

Key Properties

About Goodfellow

Background

Polyethylene terephthalate polyester (PETP) is the most common thermoplastic polyester and is often called just “polyester”. This often causes confusion - not only is the chemically similar polybutylene terephthalate (PBT) also a (thermoplastic) polyester, the most common resin system used in GRP is also a polyester system - and also often called just “polyester”. (In this latter case, however, the polyesters are chemically unsaturated and are “free-radical polymerised” into a thermoset).

General Properties

Polyethylene terephthalate polyester (PETP) is a hard, stiff, strong, dimensionally stable material that absorbs very little water. It has good gas barrier properties and good chemical resistance except to alkalis (which hydrolyse it). Its crystallinity varies from amorphous to fairly high crystalline. Polyethylene terephthalate polyester (PETP) can be highly transparent and colourless but thicker sections are usually opaque and off-white.

Polyethylene Terephthalate Films

Polyethylene terephthalate polyester (PETP) is widely known in the form of biaxially oriented and thermally stabilised films usually referred to by their main brand names Mylar, Melinex or Hostaphan. Strictly speaking, these names should be used only for this type of film whose properties are different from, and in several respects superior to, those of “ordinary” polyethylene terephthalate (PET) film.

Applications

These “Mylar®-type” films are used for capacitators, graphics, film base and recording tapes etc. Polyethylene terephthalate polyester (PETP) is also used for fibres for a very wide range of textile and industrial uses (Dacron®, Trevira®, Terylene®). Other applications include bottles and electrical components.

Key Properties

The key properties of Polyethylene Terephthalate Polyester ( PETP ) are tabulated below.

Table 1. Key properties

Chemical Resistance

 

 

 

Acids – concentrated

Good

Acids – dilute

Good

Alcohols

Good

Alkalis

Poor

Aromatic hydrocarbons

Fair

Greases and Oils

Good

Halogens

Good

Ketones

Good

Electrical Properties

 

 

 

Dielectric constant @1MHz

3.0

Dielectric strength ( kV.mm-1 )

17

Dissipation factor @ 1kHz

0.002

Surface resistivity ( Ohm/sq )

1013

Volume resistivity ( Ohm.cm )

>1014

Mechanical Properties

 

 

 

Coefficient of friction

0.2-0.4

Hardness – Rockwell

M94-101

Izod impact strength ( J.m-1 )

13-35

Poisson’s ratio

0.37-0.44(oriented)

Tensile modulus ( GPa )

2-4

Tensile strength ( MPa )

80, for biax film 190-260

Physical Properties

 

 

 

Density ( g.cm-3 )

1.3-1.4

Flammability

Self Extinguishing

Limiting oxygen index ( % )

21

Refractive index

1.58-1.64

Resistance to Ultra-violet

Good

Water absorption - equilibrium ( % )

<0.7

Water absorption - over 24 hours ( % )

0.1

Thermal Properties

 

 

 

Coefficient of thermal expansion ( x10-6 K-1 )

20-80

Heat-deflection temperature - 0.45MPa ( °C )

115

Heat-deflection temperature - 1.8MPa ( °C )

80

Lower working temperature ( °C )

-40 to -60

Specific heat ( J.K-1.kg-1 )

1200 - 1350

Thermal conductivity ( W.m-1.K-1 )

0.15-0.4 @ 23

Upper working temperature ( °C )

115-170

Properties Polyethylene Terephthalate Film

 

Property

 

 

Value

Dielectric Strength @25µm thick

KV.mm-1

 

 300

Dissipation Factor @1MHz

 

 

 0.016

Elongation at Break

%

 

 60-165

Initial Tear Strength

g.µm-1

 

 18-54

Permeability to Carbon Dioxide @25°C

x10-13 cm3.cm.cm-2.s-1.Pa-1

 

 0.07-0.11

Permeability to Hydrogen @25°C

x10-13 cm3.cm.cm-2.s-1.Pa-1

 

 0.45

Permeability to Nitrogen @25°C

x10-13 cm3.cm.cm-2.s-1.Pa-1

 

 0.0034-0.0038

Permeability to Oxygen @25°C

X10-13 cm3.cm.cm-2.s-1.Pa-1

 

 0.015-0.04

Permeability to Water @25°C

X10-13 cm3.cm.cm-2.s-1.Pa-1

 

 100-115

Specific Heat

KJ.kg-1.K-1

 

 1.3

Thermal Conductivity @23°C

W.m-1.K-1

 

 0.13-0.15

Properties Polyethylene Terephthalate Fibre

 

Property

 

 

Value

Material

 

 

 Medium

 High tenacity

Specific Modulus

cN/tex

 

 

 700-800

Specific Tenacity

cN/tex

 

 36

 70-80

Density

g.cm-3

 

 1.39

 1.39

Extension to break

%

 

 36

 13-16

Modulus

GPa

 

 

 9-11

Shrinkage @100°C

%

 

 4

 1.5-6

Tenacity

GPa

 

 0.5

 0.9-1.1

About Goodfellow

Goodfellow supplies metals, ceramics and other materials to meet the research, development and specialist production requirements of science and industry worldwide.

 

 

Source: Goodfellow

 

For more information on this source please visit Goodfellow.

 

Date Added: Jun 25, 2003 | Updated: Jun 11, 2013
Comments
  1. rajasundar amirthalingam rajasundar amirthalingam India says:

    UV Resistance - any scale is there?

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