Heat distortion temperature at 1.80 Mpa

Polymer Grade Expansion coefficient (m/m/°C X 10- ) Mould shrinkage (%) Heat distortion temperature at 0.45 MPa(°C) Heat distortion temperature at 1.80 MPa (°C) Brittle temperature (°C) Melt temperature (°C) Mould temperature (°C) Maximum operating temperature (°C) Continuous use temperature (°C)... 

The thermal expansion of plastics can be increased by the incorporation of reinforcing agents or fillers into the formulation. Thns, the incorporation of ceramic powder filler into polytetraflnroethylene (PTFE) rednces the coefficient of thermal expansion. On the other hand, the incorporation of 20% glass fiber into epoxy resins will increase the coefficient of cubical expansion from 0.5 mn/mn/°C x 10" to 2.0 mn/mn/°C x 10. Reinforcanent of perfluoroalkoxyethylene improved the heat distortion temperature at 0.45 MPa from 24 C to lOO C and at 1.8 MPa from 30°C to 58°C. This was accompanied by a nominal increase in tensile strength. 

The heat distortion temperature at 0.45 Mpa is the temperature that causes a beam loaded to 0.45 Mpa to deflect by 0.3 mm. If the heat distortion temperature is lower than ambient temperature, -20°C is given. 

In the deflection temperature under load test (heat distortion temperature test) the temperature is noted at which a bar of material subjected to a three-point bending stress is deformed a specified amount. The load (F) applied to the sample will vary with the thickness (t) and width (tv) of the samples and is determined by the maximum stress specified at the mid-point of the beam (P) which may be either 0.45 MPa (661bf/in ) or 1.82 MPa (264Ibf/in ). 

At the risk of oversimplification it might be said that the Vicat test gives a measure of the temperature at which a material loses its form stability whilst the higher stress level heat distortion temperature (1.82 MPa) test provides a measure of the temperature at which a material loses its load-bearing capacity. The lower stress (0.45 MPa) heat distortion temperature test gives some rather intermediate figures and it is perhaps not surprising that it is today less often quoted than the other two tests. 

HOT Heat Distortion Temperature, or heat deflection under load (HDUL). A three-point flexural test is performed on a bar by applying a load to create a stress of either 1.80 MPa or 0.45 MPa at the midpoint. The temperature is raised by a predetermined rate and when the specimen deflects by a set amount, the temperature is quoted, in °C. 

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