Method for determining molecular weight of ethylene propylene diene monomer

Abstract

The invention discloses a method for measuring molecular weight of ethylene propylene diene monomer. The method comprises the following steps: (1) weighing standard samples and a sample to be measured; (2) respectively collecting chromatographic data of the standard samples and the sample to be detected through a detection instrument; (3) making a calibration curve based on the chromatographic data of the standard samples; (4) determining molecular weight information of the sample to be detected based on chromatographic data of the sample to be detected and the correction curve, wherein the standard samples are N narrow-distribution polystyrene molecular weight standard samples with different molecular weight levels, and N is an integer greater than or equal to 5; the sample to be detected is an ethylene propylene diene monomer sample to be detected; the detection instrument is a high-temperature gel permeation chromatographic instrument provided with an infrared detector. According to the method, the problems of unstable base line, poor result repeatability and the like caused by the change of a refraction coefficient due to the influence of temperature, impurities, additives and the like on a universal differential refraction detector are solved; and high-temperature dissolution of the sample from the outside is avoided.

Description

technical field [0001] The invention relates to the technical field of analysis and testing, in particular to a method for measuring the molecular weight of EPDM rubber. Background technique [0002] EPDM rubber is a terpolymer of ethylene, propylene and non-conjugated dienes. It has excellent ozone resistance, weather resistance, heat resistance and chemical stability. It is mainly used in housing construction, wire and cable, and automobiles. industry and other fields. EPDM rubber has the lowest density among all rubbers, the highest thermal decomposition temperature, large thermal decomposition heat absorption, large filling coefficient, and excellent compatibility with various propellants and their composite shell materials, so it is ideal The thermal insulation layer material in the solid rocket motor casing is also the most widely used type of thermal insulation layer in solid rocket motors. [0003] The national military standard "GJB 8797-2015ENB Specification for ...

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Problems solved by technology

[0006] One purpose of this scheme is to provide a method for measuring the molecular weight of EPDM rubber, which avoids the change of the refractive index of the general-purpose differential refractive index detector due to the influence of temperature, impurities, additives, etc., resulting in unstable baseline and poor repeatability of results. and other problems; avoid the tedious process of dissolving the sample at high temperature externally, and the cumbersome process of manual operation and errors caused by manual operation; avoid the problem of large experimental errors caused by inconsistent heating time of the sample and high temperature oxidation degradation

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