Improving the hydrophobic properties and mechanical abrasion of hybrid reinforced polyurethane coating with nanosilica-modified carbon nanotubes for use in gas pipelines

Polyurethane mastic coating (PU) according to IGS-M-TP-020-2 standard of Iran Gas Company is used as one of the insulation methods for pipes and fittings along with other insulation methods. In this study, hybrid nanocomposite coatings were prepared by mixing PU with 0.3 wt% by weight of multi-walled carbon nanotubes modified with different weight percentages of nanosilica in the thickness range of 1500-1000 μm. Characteristic tests were performed for coating application in gas transmission pipelines and the results were compared with pure PU sample. According to the analysis of transmission electron microscopy, the optimal amount of 1% by weight of nanosilica led to the proper dispersion of nanoparticles within the polymer structure. The high resistance of nanocomposite coating against moisture penetration and its hydrophobicity was justified by reducing the glide angle to 17o and increasing the sphericity of water droplets on the coating surface. Less than 100 mg of mass loss due to mechanical abrasion and a slight decrease in the adhesion of the coating on the steel surface (less than 15%) and the elongation (%) under standard tension in the range of 10-15% compared to pure PU coating, justifies its use as a new coating to increase the life of steel gas pipes. The results of this research regarding the mentioned tests indicate the observance of the technical standards of Iran Gas Company by the proposed coverage. Investigation of other technical requirements of the coating is essential in research futures.