Thermoplastic polyester

Thermoplastic polyester offers an amazing balance of properties considering its very low price. As a result, it dominates in textiles, films and engineering. The most important of this group is polyethylene terephthalate (PET, PETE) – a low cost plastic available in many formats and commercially significant in many industries. While they have moderate mechanical properties, they have some in-built resistance to weathering, chemicals and fire; which can be enhanced. As a packaging material polyester provides a barrier against water, CO2, oxygen and nitrogen – perhaps the most iconic use of this material is in plastic drinks bottles.

At high temperatures polyester is very sensitive to moisture and particularly vulnerable to water at over 60 degC. Copolyesters have been developed to overcome this shortfall and grades are available that are able to be utilised in reusable, transparent, dishwashable food and drink containers, for example. On the other hand, in the case of biodegradable plastics, this weakness may be enhanced to enable composting end of life. When combined with raw materials from biological sources, it is possible to make bio-based biodegradable polyesters that meet the most stringent composting requirements and are suitable for a range of packaging, textile and industrial applications.

Polyester may be partially, or wholly, derived from biomaterials. Certain types, such as polytrimethylene terephthalate (PTT), have biomaterial derived ingredients as part of their fundamental chemistry, which may or may not be advantageous, depending on the source of the material. Polyethylene furanoate (PEF) is 100% bio-based and offers a superior material to PET in many applications. These materials are not biodegradable.