Offshore pipelines are vulnerable against erosion/wear deterioration mechanisms that can be controlled through the use of proper surface coatings, such as polymer matrix nano-composite (PMNC) coatings that are well-known for their ease of production, availability and applicability. Epoxy, as a versatile rigid and brittle resin and polyurethane with proper chemical/mechanical properties, are potential candidates to make the matrix of these composites. A combination of these polymers can also enhance the mechanical behaviors, glass transition temperature and flexibility. In addition, the desired coating characteristics, such as adhesion to metal substrate, mechanical properties, erosion/wear resistivity and UV absorbance, can be further improved through the addition of appropriate nanoparticles within the polymer matrix. Especially, nanoparticles can improve the erosion/wear resistance of polymers because of establishing high strength bonds between the polymer chains and the reinforcements besides enhancing other required properties. The present work is a review on PMNC coatings that contain epoxy, polyurethane or EP/polyurethane as a polymer matrix along with the details of the nanoparticle reinforcements, such as alumina, silica, titanium oxide, zinc oxide, clay and carbon-based materials. The effect of these nanoparticles on the properties of composite coatings has also been investigated.

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Coupling agent concentration plays a key role in functionalization of SiO 2 nanoparticles as reinforcing particles. PurposeIn this study, the in uence of 3-(glycidoloxy propyl) trimethoxy silane (GPTMS) concentration on functionalization of SiO 2 nanoparticles, is experimentally investigated. MethodsThe functionalization of nano-silica were performed by 30, 50, 80 and 110 wt.% of GPTMS in order to nd the optimal GPTMS concentration to complete the process. Fourier Transformation Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Thermo Gravimetric Analysis (TGA) and X-Ray Diffraction (XRD) characterized the pure and modi ed samples; then, the results were compared to each other to achieve the aim of the research. ResultsFTIR results con rmed the silanization proceed due to the silane absorption peak disappearing and shifting of the hydroxyl group bonds in to the amide bonds. This test showed that 30 wt.% GPTMS has not been su cient for full functionalization of the NPs. According to FESEM images, it seems that the NPs were better modi ed by 80 wt.% GPTMS due to the least NPs aggregation and lack of coupling agent deposition on the NPs. Also, TGA illustrates that this sample has higher thermal stability because of lower weight loss (11.2%) in coupling agent decomposition temperature range: 130-380°C. Furthermore, X-Ray Diffraction con rmed the FESEM and TGA results about the mentioned sample due to its highest crystallite size (increase 26.64% in crystallite size in comparison with the pure sample). ConclusionSo, the 80 wt.% of GPTMS introduced as the optimal concentration for surface modi cation of SiO 2 nanoparticles.