Method for determining content of bound acrylonitrile in butadiene-acrylonitrile rubber

Abstract

The invention discloses a method for determining the content of bound acrylonitrile in butadiene-acrylonitrile rubber. The method includes the following steps: (1) heating an extracted butadiene-acrylonitrile rubber sample with the weight being m1 to 400 DEG C, cracking, collecting a crackate, and weighing the crackate constant weight being m2; (2) carrying out a test experiment, taking the crackate with the mass being m3, dissolving in dilute sulfuric acid, then putting into a container, dropping 2-3 drops of an alizarin yellow-thymolphthalein mixed indicator, and titrating the sample to light blue with a 0.1 mol / L sodium hydroxide standard solution; adding 10 mL of a sodium sulfite solution with the concentration of 126 g / L, making the solution become bluish violet, shaking evenly, covering with a bottle plug, sealing well, placing for 5 min, then titrating to faint yellow with a 0.1 mol / L sulfuric acid standard solution, and making the consumed sulfuric acid standard solution be V1; and carrying out a blank experiment, and making the consumed sulfuric acid standard solution be V0; and (3) calculating test results. The method can be applicable to measurement of the content of bound acrylonitrile in vulcanized butadiene-acrylonitrile rubber simultaneously, and moreover, the measured results are accurate and convenient.

Description

technical field [0001] The invention relates to a method for analyzing the microstructure content of rubber, in particular to a method for determining the content of bound acrylonitrile in nitrile rubber. Background technique [0002] Nitrile rubber is a copolymer of butadiene and acrylonitrile, and its combined acrylonitrile content has a great influence on its mechanical properties, adhesive properties and heat resistance. As far as the characteristics of butadiene and acrylonitrile monomers are concerned, the polarity of butadiene is weak, while the polarity of acrylonitrile is strong. Therefore, the more acrylonitrile content in the main chain of nitrile rubber, the more The worse the flexibility of the chain, the higher the low temperature brittleness temperature, the worse the low temperature resistance; but on the other hand, the heat resistance of acrylonitrile is good, because during the heating process, acrylonitrile in nitrile rubber can generate alcohol-soluble s...

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Problems solved by technology

On the other hand, in fact most of the nitrile rubber samples are vulcanized rubber products, how to analyze the bound acrylonitrile content in the vulcanized nitrile rubber is obviously more important, but in the current method, the detection method steps are complicated and the accuracy is very low. It is greatly affected by the air tightness of the instrument, the degree of digestion reaction and the absorption rate of boric acid, and many unextracted organic compounds in vulcanized nitrile rubber also contain N elements, so the accuracy of the obtained results needs to be improved