Analysis of chemical resistance of thermoplastic polymer coatings based on polyolefin in solutions of acids, salts and alkalis

The team of authors has developed a new composition of powder polymer paint, which has a number of advantages – higher adhesion, chemical resistance and sufficient mechanical strength. Studies of the chemical resistance of coatings based on powder polymer paint were carried out by exposing coating samples to solutions of acids, salts and alkalis with concentrations of 5, 10 and 15 %. Changes in the decorative and protective properties of the thermoplastic coating were observed after exposure. Analysis of the coating surface showed that the studied concentrations of salt, acid and alkali solutions do not have a significant effect on the change in the decorative and protective properties of the thermoplastic coating. Of particular interest was the observation of the corrosive effect of the medium in the coating defect after keeping the samples in NaOH, NaCl and HCl solutions with a concentration of 15 %. After exposure of metal samples with a defect in thermoplastic coating to a 15 % NaOH solution, passivation of the metal surface in the defect occurred, which is evident from the absence of corrosion products after testing. In 15 % NaCl and HCl solutions, the presence of corrosion products was visually noted. However, no significant peeling of the coating due to adhesion failure was observed. An analysis of the change in the mechanical characteristics of the coating material after its exposure to solutions of acids, salts and alkalis with a concentration of 10 % showed an acceptable decrease in the tensile strength of no more than 10 % compared to the control data. The thermoplastic coating developed in this way is recommended for use in oil and gas equipment exposed to corrosive factors.