GB/T 39714.2-2020 in English

Interpretation of the core content of the standard

This standard specifies the technical requirements for the entire process of polytetrafluoroethylene (PTFE) semi-finished products from sampling to performance testing, with a focus on standardizing the sample preparation method and the measurement procedures for 13 types of key performance indicators.

Key requirements for specimen preparation

Key points of performance measurement technology

1. Tensile performance test

GB/T 1040.2/3 standard is adopted, and the test speed is (50±5)mm/min. Please note:

• Extruded product samples need to be sampled parallel to the extrusion direction
• Turned products should be sampled perpendicular to the molding pressure direction
• Fractural strain calculation needs to consider chart rate correction

2. Density determination

When testing according to GB/T 1033.1 immersion method, the temperature correction formula is: ρ_c=ρ_m+(T_m-23)×0.00052

3. Electrical performance test

The electrical strength test needs to be carried out in oil. When the sample thickness is greater than 0.3mm, a spherical electrode should be used (Figure 1a of GB/T 1408.1)

Recommendations for the implementation of the standard

1. For dispersion resin extruded pipes, the dimensional stability test needs to select the oven time according to the wall thickness (see Table 2)
2. During the load deformation rate test, a 12.7mm cubic sample needs to be subjected to a pressure of (15±0.15)N for 24 hours
3. It is recommended to establish a sample processing traceability system to record the sampling location and direction

Technology evolution analysis

This standard is modified to adopt ISO 13000-2:2005. The main adjustments include:

• Add Appendix B Load Deformation Rate Test Method
• Update 13 referenced standards (such as replacing ISO 4599 with ISO 22088)
• Delete international standards such as ASTM D621-64