Polyesters (Thermoplastic) PETP, PBT, PET semi-crystalline

INTRODUCTION
Engineering polyesters are engineering thermoplastics based on PBT (Polybutylene terephthalate) and PET (Polyethylene terephthalate).

Polyester resins combine excellent mechanical, electrical and thermal properties with very good chemical resistance.

PROPERTIES
PBT, PET and PBT Blends are engineering plastics with excellent processing characteristics and high strength and rigidity for a broad range of applications. Typically properties in which they differentiate themselves from other engineering plastics are:

Extreme low water absorption, Exceptional dimensional stability, Excellent electrical properties, Excellent resistance to chemical attack and high environmental stress crack resistance (due to the semi-crystalline nature of polyesters), Very good heat and heat ageing resistance, Very low creep, even at elevated temperatures. Very good colour stability. Excellent wear properties

The property profile of PBT and EPET plastics is wide and varied. It would be difficult to provide one set of figures which encompass the range. Additionally the wide use of glass fillers further exasperates this position.

Psysical properties:
Tensile Strength	50 - 55	MPa
E-modulus	2300 - 3000	MPa
Notched Impact Strength	1.5 - 4	kJ/m²
Thermal Coefficient of expansion	70 - 120	x 10-6
Max Cont Use Temp	175 - 200	0C
VicatB Temp	70	0C
Density	1.37	g/cm³

The chemical resistance of polyesters is in general very good, mainly due to their robust chemical nature, but also because they are a crystalline engineering plastic.

APPLICATIONS
Engineering Polyesters can be found in the following markets: Transportation, Automotive, Electronical/Electronic, Appliances, Industrial and consumer.

Engineering polymers are used in the manufacture of a wide range of components, including under bonnet parts, exterior parts (window wiper holders and exterior mirror housing). The largest increase in usage over recent years is in the rapidly developing sector of automotive electronics,

The next largest is Electrical/Electronics, making use of high heat distortion temperatures and electrical insulation inherent in PBT i.e. connectors, circuit breakers, switches and housing for the home appliance. The Telecommunications and IT sector has similar uses in mobile phone casings, through the desire for light durable phones. Other applications: building, textile bobbins, meter housings.