Product Guide for Design Engineers - Quadrant

Effective Selection & Design Techniques
Step 2
Consider the thermal requirements of your application using both typical and extreme operating
conditions.
A thermoplastic material’s temperature resistance is broadly characterised by both its ‘temperature of
defl ection under load’ and its ‘max. continuously allowable service temperature’.
The ‘temperature of defl ection under load’, formerly called ‘Heat Defl ection Temperature [HDT]’, is related to
a certain level of stiffness at elevated temperature and it is often considered as the max. temperature limit for
moderately to highly stressed, unconstrained components.
The ‘max. continuously allowable service temperature’ is generally reported as the temperature above which
signifi cant, permanent physical property degradation occurs after long term exposure. Depending on the
environment [air, oil, …], the property considered, the degradation criterion used and the exposure time taken
into consideration, there can be several max. allowable service temperatures for one and the same material.
As such we can e.g. have the temperature at which there is a decrease in tensile strength of 50 % [measured
at 23 °C] as compared with the original value after 20.000 hours of exposure to hot air, the temperature at
which there is a decrease in impact strength of 50 % [measured at 23 °C] as compared with the original value
after 10.000 hours of exposure to hot oil.
The melting point of semi-crystalline plastic materials and the glass transition temperature of amorphous ones
are the short-term temperature extremes to which form stability is maintained. For most engineering plastics,
using them at or above these temperatures is to be avoided.
Note, however, that the maximum allowable service temperature depends in many cases essentially on the
duration and the magnitude of the mechanical stresses to which the material is subjected i.e. on the max.
deformation one can allow in a given application [see fi g. 6].
Fig. 6:
Examples of Thermal Performance
Temperature of defl ection under load
acc. to ISO 75/Method A: 1.8 MPa [°C]
C 450°
400°
350°
300°
250°
200°
150°
100°
50°
0
Ertalon ® 66SA
Nylatron ® NSM
Ertacetal ® C
Ertalyte ®
Fluorosint ® 500
Quadrant ® PPSU
Techtron ® HPV PPS
Ketron ® 1000 PEEK
Duratron ® T4203 PAI
Duratron ® CU60 PBI
450° C
400°
350°
300°
250°
200°
150°
100°
50°
0
Max. allowable service temperature in air
continuously for min. 20.000 h [°C]
10