Characterization and adhesive performance of phenol-formaldehyde resol resin reinforced with carbon nanotubes

Chemical, physical, thermal properties and bonding quality of phenol-formaldehyde resol resin (PF) synthesized with single-walled carbon nanotubes (SWCNTs) was evaluated at varying ratios from 1 wt% to 5 wt%. The effect of the SWCNTs addition on thermal and chemical properties of the PF resins was characterized by thermal gravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy, respectively. FT-IR analysis revealed that the peaks of the modified PF resol resins were similar to those of the reference (laboratory-produced) PF resol resin. These similarities indicated that the synthesis of the resins with phenol, formaldehyde, and carbon nano tubes was successful. The PF resins modified using SWCNTs demonstrated higher thermal stability than the reference PF resin. It was found that the bonding strength of the PF resin containing 3 wt% SWCNTs could reach 12.45 N/mm2 in dry conditions and 7.57 N/mm2 in wet conditions. The bonding test results demonstrated that the SWCNTs were able to improve the bonding performance of the resin under dry and/or wet conditions. This work presents an effective method to improve PF resins with SWCNTs reinforcement for use in the wood and/or polymer composite industries.