GB/T 34247.1-2017 in English
VALIDDetermination of the unsaturation of isobutene-isoprene rubber--Part 1: Iodometry
- Issued on:2017-09-07
- Implemented on:2018-04-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
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《GB/T 34247.1-2017异丁烯-异戊二烯橡胶（IIR）不饱和度的测定 第1部分：碘量法》由TC35（全国橡胶与橡胶制品标准化技术委员会）归口，TC35SC6（全国橡胶与橡胶制品标准化技术委员会合成橡胶分会）执行，主管部门为中国石油和化学工业联合会。
Introduction
National Standard of the People's Republic of China GB/T 34247.1—2017
Determination of unsaturation of isobutylene-isoprene rubber (IIR) Part 1: Iodometric method
Background and significance of standard formulation
This standard was proposed by China Petrochemical Corporation to provide a scientific and unified method for the determination of unsaturation of isobutylene-isoprene rubber (IIR). As an important synthetic rubber material, IIR is widely used in many industries, and its performance is closely related to the unsaturation. The determination of unsaturation by iodometric method can effectively evaluate the quality and applicability of rubber.
Scope
| Item | Content |
|---|---|
| Applicable objects | Isobutylene-isoprene rubber (IIR) raw rubber, also known as butyl rubber (IIR) |
| Determination method | Iodine titration, nuclear magnetic resonance hydrogen spectroscopy is not involved |
Reagents and Materials Specifications
The following are the key reagents and materials specified in the standard:
- Carbon tetrachloride (CCl4): used as a solvent, ensure that it is free of water and impurities.
- Iodine bromide carbon tetrachloride solution: The concentration is 0.05 mol/L. The preparation requires precise temperature control and storage in the dark.
- Potassium iodide solution: The mass fraction is 10%, used for post-reaction treatment.
Instrument and Equipment Requirements
| Instrument Name | Specifications and Model | Purpose |
|---|---|---|
| Analytical Balance | Accurate to 0.1 mg | Used for accurate weighing of samples and reagents |
| Burette | 50 mL, graduation value 0.1 mL | Used for titration of sodium thiosulfate standard solution |
Detailed Analysis Steps
- Sample Preparation: Cut the sample into 2.0
- Dissolution and reaction: Add 50 mL of carbon tetrachloride and shake on an oscillator for 2-3 hours until completely dissolved. Then add 15 mL of iodine bromide solution and react in a constant temperature water bath in the dark for 30 minutes.
- Titration process: After adding potassium iodide and distilled water, titrate the generated iodine with sodium thiosulfate standard solution and use starch indicator solution to determine the end point.
Result calculation and formula
Iodine value (I) is calculated according to the following formula:
Unsaturation (U) is converted into mole fraction and calculated according to the formula:
Repeatability and data processing
The absolute difference between two parallel determination results should not exceed 0.05%. The calculation results should be rounded according to GB/T 8170 and retain two decimal places.
Implementation Advice
- Operators should receive professional training to ensure safety and accuracy during the experiment.
- Laboratories need to calibrate instruments and equipment regularly and ensure the effectiveness and purity of reagents.
- Record detailed test reports, including all abnormal phenomena and instructions for optional operations.
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