Analysis of factors affecting the determination of the degree of curing epoxy coatings of oil and gas pipes by differential scanning calorimetry

Abstract

The use of internal protective coating of steel pipes is one of the most effective and reliable ways to prevent corrosion. The most widespread coatings based on epoxy film-forming exhibit high adhesion to steel and chemical resistance to various aggressive factors. The formation of epoxy coatings is intimately connected with the interactions occurring on the metal surface, the physicochemical properties of the polymer itself and with the process of curing (polymerization), as well as with the thermophysical parameters that change during curing (glass transition temperature, degree of curing). The method of differential scanning calorimetry is widely used in practice to determine glass transition temperature which provide detecting phase transitions and their values in different materials. The accuracy of this method depends on many factors related to the instrument properties and methodological approaches which leads to a lack of repeatability and reproducibility of test results in various laboratories, and as a result, to the absence of a unified criteria for assessing the quality of protective coatings. We present the results of studying the degree of curing the epoxy coatings of oil and gas pipes by differential scanning calorimetry. The effect of instrumental conditions for laboratory tests, sample preparation methods, and methods of data processing by specialized software on the determination of thermophysical properties of epoxy coatings by differential scanning calorimetry was revealed. The results obtained can be used in developing a refined procedure for determining the degree of curing protective coatings.