Information on the most widely used ASTM standards within the materials testing industry
ISO 75-1 Plastics -- Determination of temperature of deflection under load.
ISO 75-1 specifies a general test method for the determination of the temperature of deflection under load (flexural stress under three-point loading) of plastics. Different types of test specimen and different constant loads are defined to suit different types of material. It is determined for materials such as thermoplastics, hard rubber and duroplastic laminates.
Test Scope:
Heat deflection temperature is defined as the temperature at which a standard test bar deflects a specified distance under a load. It is used to determine short-term heat resistance. It distinguishes between materials that are able to sustain light loads at high temperatures and those that lose rigidity over a narrow temperature range.
Test Procedure:
The bars are placed under the deflection measuring device. A load of 0.45 MPa or 1.80 MPa is placed on each specimen. The specimens are then lowered into a silicone oil bath where the temperature is raised at 2° C per minute until they deflect 0.25 mm for ASTM, 0.32 mm for ISO flatwise, and 0.34 mm for ISO edgewise.
Test Data:
Temperature at the specified load and deflection.
Specimen size:
| ASTM D648 | standard bar 5" x ½" x ¼" |
| ISO edgewise | uses a bar 120mm x 10mm x 4mm. |
| ISO flatwise | uses a bar 80mm x 10mm x 4mm. |
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