Heat Distortion Temperature at 1.80 MPa C

The HDT at 0.45 MPa is the temperature, which causes a beam loaded to 0.45 MPa to deflect by 0.3 mm. If the HDT is lower than the ambient temperature a value of 20 °C is given. 

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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. 

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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