ASTM D7474-2017 通过浸入各种化学试剂法测定挤压或模铸砜塑料件中残余应力的规程 Standard Practice for Determining Residual Stresses in Extruded or Molded Sulfone Plastic (SP) Parts by Immersion in Various Chemical Reagents

1.1 This practice covers the evaluation of residual stresses in extruded profile or molded SP parts. The presence and relative magnitude of residual stresses are indicated by the crazing of the specimen part upon immersion in one or more of a series of chemical reagents. The specified chemical reagents were previously calibrated by use of Environmental Stress Cracking (ESC) techniques to cause crazing in sulfone plastics (SP) at specified stress levels. 1.2 This practice applies only to unfilled injection molding and extrusion grade materials of high molecular weight as indicated by the following melt flow rates: PSU 9 g/10 min, max., PESU 30 g/10 m, max, and PPSU 25 g/10 min, max. Lower molecular weight (higher melt flow) materials will craze at lower stress levels than indicated in Tables 1-3. (See Specification D6394 for melt flow rate conditions.) TABLE 1 Liquid Reagents for Residual Stress Test for PSU Mixture Mixture Composition Critical Stress, MPa (psi) % by volume Ethanol % by volume Ethyl Acetate 1 50 50 15.2 (2200) 2 43 57 12.1 (1750) 3 37 63 9.0 (1300) 4 25 75 5.5 (800) TABLE 2 Liquid Reagents for Residual Stress Test for PESU Mixture Mixture Composition Critical Stress, MPa (psi) % by volume Ethanol % by volume MEK 1 50 50 17.9 (2600) 2 40 60 10.3 (1500) 3 20 80 6.9 (1000) 4 0 100 5.9 (850) TABLE 3 Liquid Reagents for Residual Stress Test for PPSU Mixture Mixture Composition Critical Stress, MPa (psi) % by volume Ethanol % by volume MEK 1 50 50 22.8 (3300) 2 25 75 13.8 (2000) 3 10 90 9.0 (1300) 4 0 100 8.0 (1150) 1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. Note 1: There is no known ISO equivalent for this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility