Fabrication and characterization of polystyrene modified epoxy resin based nanocomposite and hybrid composites

In this study, firstly, the curing degrees of bisphenol-A type epoxy resin and epoxy phenolic novolac (EPN) resins were calculated for matrix determination and it was decided to continue with EPN. EPN resin was modified with 1-5% by mass of thermoplastic polystyrene (PS) waste and the most suitable ratio was selected as 4% PS and used as the polymer matrix for the first time. Two types of composites were prepared: (i) nanocomposites containing 1-4% by mass of nanoclay (NC) and (ii) hybrid composites. Pure (NC) and tetramethylammonium chloride (TMAC) modified nanoclay (MNC) were used in hybrid composites containing 15-35% by mass of red mud waste (RMW) at the most appropriate rate of 2% by mass. The chemical structures of nanoclays were elucidated by Fourier Transform Infrared Spectroscopy (FTIR) and characterized by particle size analysis. The surface morphology of nano and hybrid composites was characterized by Scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of PS, NC, and RMW on the mechanical, dynamic-mechanical, thermal and flammability properties of composites were investigated. Burning of the EPN-PS matrix decreased with the addition of NC or MNC and RMW. In addition, the corrosion protection properties of hybrid composite coatings were determined by immersion test in 5% NaOH, HCl, and NaCl solutions. The water sorption of hybrid composites ranged from 1-3.6% to 1-5.3%, while it ranged from 0.82 to 1.02% in EPN-PS/NC nanocomposites. The mass increase percentage values (0.59-0.75% and 0.46-0.59%, respectively) of the hybrid composites for the base and salt solutions in the corrosive environment were determined to be much lower than the water sorption. The morphologies of hybrid composite coatings were examined with scanning electron microscopy (SEM) before and after corrosion tests, and surface properties were examined with a microscope. 2% MNC-30% WC hybrid composite is more suitable than 2% NC-30% WC composite due to its high corrosion resistance, storage modulus, loss modulus, and glass transition temperature (Tg) values (90.6°C) in basic and salty environments found.