Influence of additive of Chlorophytum comosum plant extract on physicochemical, structural and mechanical properties of urea formaldehyde resin

In this research the effect of additive of Chlorophytum comosum (C. comosum) plant extract on physicochemical, structural properties and shear strength of urea formaldehyde (UF) resin was investigated. C. comosum leaf extraction was performed according to the method of Bondareva et al. (2017) and was added to UF adhesive at two levels of 5 and 10%. The properties of adhesive such as solid content, gelation time, pH, density and free formaldehyde were measured before and after adding the extract. To identify the possible chemical structures of the reaction between the components of the adhesive and the extract and to investigate the reactions' bonds and intensity, matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI ToF) and Fourier transform infrared spectroscopy respectively, were performed. The shear strength test of the plywood was used according to EN 314-2. Based on the results of physicochemical properties, the formation of multiple hydrogen bonds between the active functional groups of the adhesive and the extract led to an increase in intermolecular forces and an increase in the cohesive strength of the adhesive, thereupon the amount of free formaldehyde in the adhesive decreased by 16.67% with the highest amount of extract. The possible chemical structures of the reaction of some active functional groups of the extract with UF adhesive were confirmed by MALDI TOF mass spectrum. The addition of C. comosum extract weakened the absorption intensity of UF adhesive' peaks, which indicates that the extract of active groups reduced the formation of chemical bonds, including methylene and ether bonds in the adhesive. The significant improvement in shear strength of plywood obtained from adhesives containing the extract can be attributed to the quality of cross joints and increase of adhesive density so that the highest shear strength of plywood was 2.07 MPa with adding 10% of the extract.