Preparation and characterization of epoxy/oregano oil as an epoxy-based coating material with both antimicrobial effect and increased toughness

The main objective of this work is to prepare an epoxy-based hybrid material with antimicrobial activity and increased toughness using a natural modifier. Therefore, oregano essential oil (OEO) was employed as a new additive for an epoxy thermosetting polymer. Mechanical properties of epoxy/OEO hybrids with different OEO contents were studied. Impact strength and fracture resistance of the hybrids were increased with increasing OEO content up to 15%. With the addition of 15% OEO to epoxy, maximum improvements of 69% and 83% were obtained for impact and fracture properties, respectively. Tensile properties of the hybrid decreased somewhat with increasing OEO content. Morphological properties of the epoxy/OEO hybrids were studied using scanning electron microscopy and Fourier transform infrared spectrometry. A dispersion of micron-sized OEO particles in epoxy matrix with relatively strong interactions between two phases in the interfacial area was observed as the main morphology. Antimicrobial activity of epoxy/OEO hybrids was examined using the disk diffusion method. The hybrid samples clearly showed antimicrobial activity against gram-positive and gram-negative bacteria. The hybrid had higher antimicrobial activity for fungus strain in comparison with bacterial strains.