Proceedings World Geothermal Congress 2020+1 Reykjavik, Iceland, April - October 2021 1 Polymer/clay Nanocomposite: A Viable Anti-Corrosion Coating for Geothermal Applications Jennifer Espartero-Dales 1 , Al Christopher de Leon 2 , Eugene Caldona 3 and Rigoberto Advincula 4 1 Energy Development Corporation, Southern Negros Geothermal Production Field, Ticala, Valencia, Philippines 2,4 Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio, USA 3 University of the Philippines- Diliman, Quezon City, Metro Manila, Philippines espartero.jc@energy.com.ph Keywords: nanocomposite coating, high temperature, corrosion, electrochemical testing ABSTRACT Polymer modification has been attracting the attention of the scientific community due to its process of combining attractive properties of different materials and fusing it into a hybrid high performance material. These properties depend on the type of environment and its application. Due to the harsh conditions imposed by geothermal fluids to ordinary materials of construction, high performance materials are desired to lessen the frequency or even eliminate maintenance cleaning of surface components and to prolong the service life of pipelines and other surface equipment that are critically affected by erosion-corrosion phenomenon. To further enhance the mechanical properties of a high performance polymer material, nanofillers are usually incorporated in the polymer matrix to make up a nanocomposite. In this study, a nanocomposite (PCN-R-oMMT) made of toughened polymer and organically modified montmorillonite was synthesized to be used as a coating. The enhancement of the mechanical properties of the polymer by addition of oMMT by its intercalation/exfoliation into the polymer matrix was determined using X-Ray Diffraction (XRD), thermogravimetric tests (TGA & DSC), hardness test, and adhesion test. To determine the viability of the synthesized coating in corrosive environment, it was applied to a carbon steel coupon and immersed in simulated acidic geothermal brine. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization scans (PPS) were conducted to assess the protection efficiency of the coating. The stability and the protection efficiency of the PCN-R-oMMT were also evaluated under high temperature and high pressure conditions. 1. INTRODUCTION Geothermal production is hindered by scaling and corrosion problems. Both of these problems entail high cost and pose high risk in terms of material and environmental safety. The chemistry of each production well is unique, making it challenging to find an anti- corrosion solution that would fit into the nature of the fluid. This is especially true of acid-producing wells that corrode metal casing and pipelines at a very fast rate. Most of these wells are unusable due to the aggressive behavior of their fluids because of fast metal dissolution destroying the integrity of the pipe. The utilization of these wells, therefore, is dependent on the use of an effective corrosion prevention technology that would significantly lower the rate or retard the corrosion process. One way of retarding the effects of corrosion is by application of coatings. Due to the relatively high temperature nature of a geothermal process, coatings to be applied must have good thermal stability and high resistance to chemical attack. The issue of hardness and adhesion also needs to be considered in choosing the right material since geothermal fluid does not only contain corrosive agents but may contain high amounts of suspended solids. These high velocity solids will impinge on the walls of the pipe, eroding the metal. Erosion together with corrosion would have a synergistic effect on the rate of metal dissolution, making it a critical factor to consider in operating a highly erosive and corrosive environment. Polymer modification has been attracting the attention of scientific community due to its process of combining attractive properties of different materials and fusing it into a hybrid high performance material. These properties depend on the type of environment and its application. For this study, we have chosen to modify a polymer (PCN) to tailor the needs of a typical acidic geothermal well. The polymer has excellent properties that fit the requirements such as near-zero shrinkage upon polymerization, low surface free energy, low water absorption, good thermal stability, and good mechanical properties, as observed in the studies of Ishida et al. (2011). Zhou et al. (2013) reported that although there has been few studies conducted regarding the use of PBZ for anticorrosion, polybenzoxazines have the potential for application as corrosion protective coating due to their unique properties, such as low water absorption, low surface free energy, near-zero shrinkage, and excellent dielectric properties, which are superior to those of epoxy resins and conventional phenolics. However, the polymer is brittle and needs to be modified to be able to expand the limits of its application as discussed by Ishida and Allen (1996). Several approaches have been designed to toughen thermosetting materials and one of the most promising is the modification with rubber. It has been found that rubber modification is an effective approach to overcome the inherent brittleness of thermosets. For instance, physical blends of polymer and rubber have improved fracture toughness without undue sacrifices to the desirable properties, as shown by the study of Jang and Yang (2000). Hence, in our study, the polymer is toughened by blending the synthesized polymer with rubber. To further enhance the mechanical properties of a high performance polymer material, nanofillers are usually incorporated in the polymer matrix to make up a nanocomposite. One critical factor in making an effective polymer nanocomposite is the type of nanofiller to be used. Based on the study conducted by Hung et al. (2011), clay nanocomposites show enhanced physical properties even with a small amount of added clay because the nanoscale dimensions of the clay particles yield a large contact area between the polymer matrix and the filler. The structure of clays also imparts an excellent barrier that provides low gas permeability and