In this study, phenolic novolac-type epoxy (EPN) resin was modified with 4 wt % thermoplastic polystyrene (PS) waste and was used as the polymer matrix for the first time. Two types of composites were prepared: (i) nanocomposites with 1-3 wt% nanoclay (NC) and (ii) hybrid composites. Pristine (NC) and tetramethylammonium chloride modified nanoclays (MNC) were used at a 2 wt% ratio in hybrid composites with 25-35 wt% red mud waste (RMW). The corrosion protection properties of the coatings were determined by immersion test in 5 wt% NaOH, HCl, and NaCl solutions. The water sorption of hybrid composites varied between 1%-3.6% and 1%-5.3%, while it was between 0.82% and 1.02% in EPN-PS/NC nanocomposites. The weight gain percentage values of hybrid composites in corrosive media for the base and salt solutions were determined much lower (0.59%-0.75% and 0.46%-0.59%, respectively) than water sorption. Surface morphologies of hybrid composites were examined by scanning electron microscopy before and after corrosion tests. MNC-30 wt% RMW hybrid composite was found more suitable due to high corrosion resistance in basic and salty environments, storage modulus, loss modulus, and glass transition temperature (T g ) values (90.6 C) as compared with NC-30 wt% RMW hybrid composite.
In this study, walnut shell (WSh), hazelnut shell (HSh), and mussel shell (MSh) waste as inexpensive reinforcements were recycled for the preparation of epoxy composite materials. Subsequent used inexpensive fillers are chars (WShC and HShC), which are the pyrolysis solid products of the natural WSh and HSh wastes. Three types of epoxy resins: bisphenol-A type (DGEBA), modified with polyurethane (MER with PU), and rubber modified (MER with rubber) epoxy resins were used as the matrix in MSh composites. Thermogravimetric analysis of the composites showed that the thermal strength of the epoxy matrix increased significantly with the MSh and chars. The best water sorption results were obtained with the MSh. The contact angle values of MSh composites prepared with DGEBA epoxy resin were quite high (111 -113.5 ) and their water retention values ranged from 0.2% to 0.32%. The composites that were produced using 50 wt% chars and the same epoxy resin showed better flammability stability. The full extinction times were determined as 63 and 58 s for WShC and HShC composites, respectively.
In this study, bisphenol A-type epoxy (ER) and epoxy phenol novolac resins (EPN) with two amine-type curing agents (KH 816 and IPOX EH 2041) having different total amine values were selected. The mechanical properties and density of the EPN resin were found higher in the case of both curing agents. EPN was modified with polystyrene (EPN-PS) and used as a matrix using an IPOX hardener. Nano-and hybrid composites were prepared with pristine and modified with tetramethylammonium chloride nano montmorillonite (NC and MNC), and red mud waste (RMW). The chemical structure was elucidated by the Fourier transform infrared (FT-IR). The composites were characterized by scanning electron microscopy and x-ray diffraction. Appropriate PS and NC ratio was accepted as 4% and 2% by weight, respectively. Curing degrees calculated from the FT-IR spectra of ER, EPN, and EPN-PS were 99.3%, 99.9%, and 86.5%, respectively. A comparative study of the two binary systems; (i) 2 wt% NC-(15-35) wt% RMW; and (ii) 2 wt% of MNC-(15-35) wt% of RMW on the mechanical, thermal, and flammability properties of EPN-PS matrix was carried out. The appropriate RMW ratio was 30 wt%. Hybrid composites with 25-30 wt% RMW can be considered self-extinguishing materials.
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