GB/T 18251-2019 in English
VALIDMethod for the assessment of the degree of pigment or carbon black dispersion in polyolefin pipes,fittings and compounds
- Issued on:2019-08-30
- Implemented on:2020-03-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$214.00
《GB/T 18251-2019聚烯烃管材、管件和混配料中颜料或炭黑分散度的测定》由TC48（全国塑料制品标准化技术委员会）归口，TC48SC3（全国塑料制品标准化技术委员会塑料管材、管件及阀门分会）执行，主管部门为中国轻工业联合会。
Introduction
Interpretation of the core content of the standard
This standard specifies a dual-track evaluation system for evaluating the dispersion quality of additives in polyolefin materials through microscopic observation: size grade (quantitative measurement) and apparent grade (qualitative comparison). It is mainly applicable to polyolefin products with a carbon black content of less than 3%, and the comparability of test results is ensured through standardized sample preparation processes and grading standards.
Key Technical Changes
| Change Dimensions | 2000 Edition | 2019 Edition | Technical Significance |
|---|---|---|---|
| Microscope Requirements | Fixed 70× Magnification | Dynamic Matching Magnification (100×/70×) | Improve Adaptability to Observation of Different Particle Sizes |
| Sample Thickness | Uniform Requirements | Pigment (60±20)μm Carbon Black (20±10)μm | Differentiate Material Properties and Optimize Observation Effects |
| Grade Assessment | Single size standard | Added apparent grade comparison (Appendix B) | Establish morphology evaluation dimension |
Key points of the detection process
Specimen preparation specifications
Note when using the tabletting method:
- Pigment sample mass (0.6±0.2) mg, carbon black (0.2±0.1) mg
- Precise control of heating temperature in the range of 150-210℃
- Use spring clamps to ensure thickness uniformity
Key points of microscopic observation
Implement dual-track evaluation:
- Size grade: Measure >5μm particles at 100× and refer to Table A.1 for classification
- Apparent grade: Compare with Appendix B microscopic spectrum at 70×
Implementation suggestions
Quality control threshold
According to Appendix D requirements:
- Size grade ≤3.0
- Apparent grade ≥Grade B (better than Grade C in Figure B.1)
Prevention of common errors
The test report must record:
- Sample preparation bubbles/impurities
- Departures from standard operation details
- Ambient temperature and humidity fluctuations
Standard evolution analysis
This standard is modified using ISO 18553:2002, the main technical differences include:
- Delete the description of the double sample preparation method and strengthen the dominant position of the tableting method
- Refine the flow chart of the apparent grade determination (new informative Appendix D)
- Improve the test report elements and add examples of interference factors
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