GB/T 2951.42-2008 "General Test Methods for Cable and Optical Cable Insulation and Sheath Materials, Part 42: Special Test Methods for Polyethylene (PE) and Polypropylene (PP) Mixtures" specifies specific test methods for a variety of polyolefin insulation and sheath materials, including tensile strength and elongation at break after high temperature treatment, winding test after high temperature treatment, winding test after air heat aging, mass increase determination, long-term thermal stability test and copper catalytic oxidation degradation test methods. These tests are used to evaluate the performance of materials under various high temperature and aging conditions to ensure their Reliability and Stability in cable and optical cable applications. Miscellaneous related test methods are also referenced to support a comprehensive material performance assessment.