EN ISO 75-1 Plastics - Determination of Deflection Temperature Under Load - Part 1: General Test Method

The EN ISO 75-1 standard, developed by the International Organization for Standardization (ISO) , describes a general test method for determining the deflection temperature of plastics under load (bending stress under three-point loading). This standard defines different test specimen types and different constant loads to suit different material types.

In fact, the EN ISO 75 standard consists of three parts under the heading "Plastics - Determination of deflection temperature under load":

• EN ISO 75-1 Part 1: General test method
• EN ISO 75-2 Part 2: Plastics and ebonite
• EN ISO 75-3 Part 3: High strength thermoset laminates and long fiber reinforced plastics

With the methods in these standards, the relative behavior of different material types at high temperature under load at a certain temperature increase rate is evaluated. In practice, fundamental factors such as loading conditions and nominal surface tension differ from test conditions. Therefore, the results obtained do not always represent the maximum applicable temperatures. Actual comparability of data is provided only for materials with the same room temperature modulus of bending.

Data obtained using the test methods described are not used to estimate actual end-use performance. The data are not intended for design analysis or estimation of the durability of materials at elevated temperatures.

The test method presented in the EN ISO 75-1 standard is commonly known as heat deflection temperature or heat distortion temperature test.

The following major changes have been made in the last update of this standard:

• The specification for the temperature difference between the middle and ends of the test specimens has been removed.
• The specification has been expanded for the location of the tip of the temperature sensor.

During testing, a standard test specimen is subjected to three-point bending under a constant load raised flat at a uniform rate, and the temperature at which the standard deviation corresponding to the specified increase in bending stress occurs is measured.

Among the numerous test, measurement, analysis and evaluation studies it provides for businesses in various sectors, our organization also provides testing services for the determination of the deflection temperature of plastics under load, within the scope of EN ISO 75-1 standard, with its trained and expert staff and advanced technological equipment.