GB/T 34247.2-2018 in English

GB/T 34247.2-2018 Standard Interpretation

The determination of unsaturation of isobutylene-isoprene rubber (IIR) is an important test indicator in the rubber industry. This standard provides an accurate and efficient determination method through nuclear magnetic resonance hydrogen spectroscopy. This method combines modern analytical technology with standardized processes to ensure the accuracy and reliability of the results.

Standard Background and Significance

Isobutylene-isoprene rubber (IIR) is an important synthetic rubber widely used in tire manufacturing and other fields. Its unsaturation is one of the key indicators for evaluating rubber performance. The formulation of this standard fills the gap in the industry's demand for standardization of this test method and provides strong support for quality control in the rubber industry.

Determination Principle and Technology Evolution

Nuclear magnetic resonance hydrogen spectroscopy (${}^{1}\mathbf{H}$ -NMR) is a technology for analysis based on the magnetic characteristics of hydrogen nuclei. Its core is to reveal the unsaturation information in the molecular structure by measuring the hydrogen atom signals in different chemical environments in the sample.

Compared with the traditional iodine titration method, this method has higher sensitivity and accuracy, avoids the tedious handling of chemical reagents, and reflects the advantages of modern analytical technology.

Comparison of standard frameworks

Instrument and reagent requirements

The following are the main instruments and reagents required in the determination process:

• NMR spectrometer: frequency of 400 MHz or higher, supporting Fourier transform.
• Analytical balance: accuracy to 0.1 mg.
• Reagents: deionized chloroform (CDCl3), purity greater than 99.8% (molar fraction), containing 0.03% tetramethylsilane (TMS) as internal standard, NMR grade.

Sampling and analysis steps

Sampling: Carry out according to the provisions of GB/T15340.

Sample preparation: Take about 20-30 mg of sample and dissolve it in 0.5 mL-0.6 mL deionized chloroform for at least 4 hours at room temperature.

Result calculation and precision

Unsaturation formula: \( U = \frac{8A}{A+B+C} \times 100 \)

Implementation suggestions

To ensure the effective implementation of the standard, it is recommended that:

• Operators need to receive professional training.
• Instrument calibration should be performed periodically to ensure accuracy.
• The measurement should be performed strictly in accordance with the parameters and conditions specified in the standard.
• A data sharing mechanism should be established between laboratories to improve detection efficiency.