Thermoplastic materials considered high performance or advanced, are those that mechanically resist high temperatures.
The great enemy of the thermoplastic is the temperature, both positive and negative, and these offer a high added value.
Thermoplastics such as PEEK, EPI, PEI, PVDF, etc … They are increasingly common and applied in all types of industry.
Thanks to their high temperature resistance, physiologically inert thermoplastics, mostly resist chemical attack and are highly dimensionally stable. Every day they are used in a greater number of applications, in new sectors, such as the medicine, food, chemical, aeronautics industry …
When applying high temperature resistance applications, consider whether the thermoplastic is static or there is a mechanical function. If the thermoplastic has no mechanical function, only thermal or electrical insulation function, THE MAXIMUM AIR WORKING TEMPERATURE is valid as a reference.
MAXIMUM WORKING TEMPERATURE IN TMT AIR – Continuous Service Temperature
It is defined as the maximum working temperature – in air – that the thermoplastic can withstand maintaining at least 50% of its initial mechanical properties (eg tensile strength, stiffness, ductility) after 100,000 hours of continuous work
- Related terms: high temperatures, relative thermal index, maximum use temperature.
- Test method: UL746 or best available estimated data
- Units: ºC
- Example: if we use the POM C at a temperature below its TMT of 105ºC, it will retain at least 50% of its initial mechanical properties.
Any type of material, including metallic materials, is conditioned by the temperature of work, which from certain levels produces the creep of the materials and, consequently, seizing. Thermoplastics or technical plastics are excellent insulators offering resistance to heat dissipation generated. That is why it is important to distinguish which exposure is made of the thermoplastic at that temperature, if the work is continuous or intermittent, the temperature resistance of the thermoplastic varies depending on the exposure time.
If the thermoplastic is applied with high temperature (from 100ºC) and also with mechanical function (moving and supporting a load), it is very important to look at the data of the DEFORMATION TEMPERATURE under LOAD or HEAT DEFORMATION.
The properties of thermoplastic materials experience a significant decrease in their resistive characteristics depending on the working temperature to which they are subjected. In thermoplastics or technical plastics the value of the DEFORMATION TEMPERATURE UNDER LOAD or HEAT DEFORMATION has greater practical utility than the MAXIMUM WORKING TEMPERATURE IN AIR.
DEFORMATION TEMPERATURE UNDER TDC LOAD – Heat Deflection Temperature
It is the temperature at which a 12.7mm thick rod supported between the ends at 101mm, a centered load of 1.8 MPa is applied and yields with an arrow of 0.254mm. Recalling the concepts used in the flexural module, we can see that this is another way to say “the temperature at which the flexural modulus of the specimen has dropped to 0.97Mpa”.
It is also called distortion temperature or TD. These measurements are very often the way to determine the behavior of the material to retain its properties (for example stiffness) when the temperature rises. This is not strictly true. Using AMD (dynamic mechanical analysis) curves is more reliable; The TDC serves as an approximate guide to determine the maximum working temperature under load
- Related terms: high temperature stiffness, AMD distortion heat temperature, module
- Test method: ISO 75
- Units: ºC
- Example: Polysulfone PSU is rigid up to 170 ° C. The PEEK reinforced with 30% fiberglass is up to 315 ° C. Note that these temperatures are the TDC of the aforementioned materials.
