【国外标准】 Standard Practices for Evaluating the Resistance of Plastics to Chemical Reagents

4.1 There are limitations of the results obtained from these practices. The choice of types and concentrations of reagents, duration of immersion or stress, or both, level of stress, temperature of the test, and properties to be reported are necessarily arbitrary. The specification of these conditions provides a basis for standardization and serves as a guide to investigators wishing to compare the relative resistance of various plastics to chemical reagents.4.2 Correlation of test results with the actual performance or serviceability of plastics is necessarily dependent upon the similarity between the testing and the end-use conditions. For applications involving continuous immersion, the data obtained in short-time tests are of interest only in eliminating the most unsuitable materials or indicating a probable relative order of resistance to chemical reagents.4.3 Evaluation of plastics for special applications involving corrosive conditions shall be based upon the particular reagents and concentrations to be encountered. Base the selection of test conditions on the manner and duration of contact with reagents, the temperature of the system, applied stress, and other performance factors involved in the particular application.4.4 The practices present general guidelines without covering specifics on all the varied applications of plastics, such as use in automobiles and exposure to various automotive fluids, or use in hospital environments with exposure to disinfectants and cleaning fluids. These practices can be extended to such applications with specifics on the study conducted noted in the report.4.5 The use of appropriate controls is critical to evaluate the utility of the information generated by these practices. Particular attention should be given to the variability in the data generated, especially for the baseline controls, and issues in data generation reported to mitigate misuse of information.1.1 These practices cover the evaluation of all plastic materials including cast, hot-molded, cold-molded, laminated resinous products, and sheet materials for resistance to chemical reagents.1.2 Three procedures are presented, two under practice A (Immersion Test), and one under practice B (Mechanical Stress and Reagent Exposure under Standardized Conditions of Applied Strain). These practices include provisions for reporting changes in weight, dimensions, appearance, color, strength, and other mechanical properties. Standard reagents are specified to establish results on a comparable basis without precluding the use of other chemical reagents pertinent to specific chemical resistance requirements. Provisions are made for various exposure times, stress conditions, and exposure to reagents at elevated temperatures. The type of conditioning (immersion or wet patch/wipe method) depends upon the end-use of the material. If the material is used as a container or transfer line, immersion of the specimens is used. If the material will only see short exposures or will be used in proximity and reagent will splash or spill on the material, the wet patch or wipe method of applying reagent to the material is used.NOTE 1: Practice B for evaluating environmental stress cracking resistance differs from Practice D7474, which seeks to measure residual stresses in molded sulfone plastic parts with the use of calibrated chemical reagents. Practice B differs from Test Method D1693, which seeks to quantify the susceptibility of ethylene plastics to environmental stress-cracking subjected to specific conditions, by measuring the proportion of specimens that crack in a given time.1.3 The effect of chemical reagents on properties shall be determined by making measurements on standard specimens for such tests before and after immersion or stress, or both, if so tested.1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific hazards statements are given in Section 7.NOTE 2: ISO 175 and ISO 22088 Part 3 address the same subject matter as Practices A and B of this standard, but differ in technical content and the results cannot be directly compared.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.