【国外标准】 Standard Test Method for The Un-notched, Constant Ligament Stress Crack Test (UCLS) for HDPE Materials Containing Post- Consumer Recycled HDPE

4.1 This test method is a way to evaluate the effects of contaminant particles found in HDPE products containing PCR-HDPE, primarily corrugated pipe. Particles of significant number, size and shape can reduce the slow crack growth resistance of the products. This test is performed in water without a controlled defect such as a notch. Since there is no notch, it is not necessary to use a surfactant in the water bath. It is a constant load test.4.2 This test may be used to evaluate various blends of recycled and virgin materials. For example, a material with high stress crack resistance and few contaminants can be blended with materials that are less resistant to cracking to enhance the overall stress crack resistance of the blend.4.3 The test can be conducted at various temperature and stress conditions. If at least three (3) different temperature/stress conditions are evaluated, an estimate of the service lifetime of the material can be predicted with the use of bi-directional shifting or the rate process method.4.4 The test can also be performed under a single applied load and a single temperature to create a single point test useful for comparative purposes as well as for quality control.1.1 This test method covers an un-notched constant ligament stress (UCLS) test for use with HDPE materials that contain post-consumer recycled HDPE (PCR-HDPE). Contaminants in the PCR-HDPE can initiate stress cracks at elevated temperatures, and this test method evaluates the response of these materials to a constant applied stress.1.2 The test method is focused on HDPE corrugated pipe containing PCR-HDPE, but can be used in other applications where PCR-HDPE is used.1.3 The test utilizes the same devices used to perform the NCTL test (Test Method D5397) and the NCLS test (Test Method F2136), but the test is conducted with different specimens and with the use of water instead of a surfactant solution. The test specimen is larger than standard NCLS and NCTL specimens to increase the number of contaminant particles in the specimen that might grow cracks.1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.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.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.