ASTM D 648

ASTM D 648 : Standard Test Method for Deflection Temperature of Plastics Under Flexural Load¹ This test method covers the determination of the temperature at which an arbitrary deformation occurs when specimens are subjected to an arbitrary set of testing conditions. This test method applies to molded and sheet materials available in thicknesses of 3 mm (1/8 in.) or greater and which are rigid at normal temperature. Note 1 : Sheet stock less than 3 mm (0.125 in.) but more than 1 mm (0.040 in.) in thickness may be tested by use of a composite sample having a minimum thickness of 3 mm. The laminae must be of uniform stress distribution. One type of composite specimen has been prepared by cementing the ends of the laminae together and then smoothing the edges with sandpaper. The direction of loading shall be perpendicular to the edges of the individual laminae. The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. Note 2 : The test method, ISO 75-1-1993, and ISO 75-2-1993 are technically equivalent only when the 120 by 10 by 4 mm test specimen is used and deflection temperature is measured at a depth of deflection that is a function of the depth of the specimen, and when the 5-min waiting period to allow specimen creep is applied. <more>