GB/T 39375-2020 in English
VALIDLeather—Physical and mechanical tests—Determination of dimensional change
- Issued on:2020-11-19
- Implemented on:2021-06-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$97.00
| Standard No: | GB/T 39375-2020 |
| Document status: | VALID |
| Title in English: | Leather—Physical and mechanical tests—Determination of dimensional change |
| Title in Chinese: | 皮革 物理和机械试验 尺寸变化的测定 |
| Language: | English |
| File Format: | Electronic (PDF) |
| Delivery: | Via email within 1~3 business days |
| Issued on: | 2020-11-19 |
| Implemented on: | 2021-06-01 |
| Professional Classification: | GB-National Standard |
| Related Keywords: | leather physical
dimensional change introduction analysis leather products microfiber leather dimensional changes |
| Related Topics: | elastic change
elastic change Leather GBT39375 GB/T 39375-2020 size changes Leather yellowing resistance test Leather yellowing resistance aging test Mechanical test |
《GB/T 39375-2020皮革 物理和机械试验 尺寸变化的测定》由TC252（全国皮革工业标准化技术委员会）归口，主管部门为中国轻工业联合会。
Introduction
Analysis of the core content of the standard
This standard specifies the method for determining the dimensional stability of leather through accelerated aging treatment, focusing on solving the problem of dimensional deformation caused by environmental changes during the processing and use of leather products. The drying oven and constant temperature and humidity test chamber are used to simulate the actual use environment, and the material performance is evaluated by accurately measuring the dimensional changes before and after aging.
Comparison of key technical differences
| Technical elements | ISO17130:2013 | GB/T39375-2020 | Significance of the modification |
|---|---|---|---|
| Reference standards | ISO series standards | Equivalent national standards (GB/QB) | Adapt to China's testing system |
| Specimen drawing line | Text requirements | Adjust to notes | Improve operational flexibility |
| Calculation formula | Simplified description | Refine parameter definition | Improve calculation accuracy |
Key instrument and material requirements
1. Aging equipment:Must meet the QB/T5250 requirements for temperature uniformity (±2℃) of the oven and humidity control (±3%RH) of the constant temperature and humidity chamber
2. Measuring tools:Use a vernier caliper with an accuracy of 0.1mm. It is recommended to equip it with a digital display measurement system to reduce human errors
3. Special materials: The bracket needs to be wrapped with GB/T16991 certified polyester non-woven fabric to prevent the sample from sticking.
Key points of the test process
- Sampling specification: According to GB/T39364, cut ≥2 pieces of 150×150mm specimens in the effective area and draw reference lines on the grain surface
- Pretreatment: Adjust the environment to (23±2)℃/(50±5)%RH as specified by QB/T2707 for ≥48h
- Initial measurement: Accurately record the lengths of the four reference lines (a1-d1)
- Aging treatment: Select the corresponding conditions of QB/T5250 according to the product use environment
- Final state measurement: Measure a2-d2 after re-adjustment and calculate the shrinkage rate
Result calculation and reporting
Linear shrinkage (SL):Reflects anisotropic changes and is suitable for evaluating leather with obvious directionality
Area shrinkage (SA):Comprehensively evaluates the overall dimensional stability. In the formula, (a1+c1)(b1+d1) reflects the initial area
Note:When the difference between SL and SA is greater than 15%, it indicates that the leather has significant anisotropy and should be specifically stated in the report
Implementation suggestions
- For new materials such as microfiber leather, it is recommended to add 300×300mm large sample testing
- Measurement within 5 minutes after aging can obtain "instantaneous shrinkage" data
- Regularly calibrate the measurement system with standard reference samples, recommended once a month
- Establish a material database in combination with different aging conditions of QB/T5250
Technology evolution analysis
Compared with the 2008 version, this standard has the following major improvements:
1. Introducing the concept of area shrinkage
2. Refining the technical requirements for polyester nonwovens
3. Adding anisotropy evaluation methods
4. Clarifying the applicable scenarios of specimens with different precisions
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