Synthesis and application of functionalized ionic liquids as solvent to corn stalk for phenolic resin modification

Three functionalized ionic liquids (ILs) of [HeMIM]Cl, [CeMIM]Cl, and [AeMIM]Br that can dissolve corn stalk were synthesized and characterized via Fourier transform infrared spectroscopy (FTIR) and H-1 NMR. The dissolved corn stalk was in situ blended with phenol and formaldehyde to produce modified phenolic resin composites. The resulting composites were characterized via FTIR, differential scanning calorimetry, and X-ray diffraction analysis, and tested for their mechanical properties. In addition, the effects of ILs on the dissolution rate of corn stalks and on the mechanical properties of the modified phenolic resin were investigated as well. The results showed that the synthesized ILs presented good solubility toward corn stalk at the optimum temperature of 90 degrees C. After modification with corn stalk dissolved in ILs, the mechanical properties of phenolic resin were significantly improved. At the same conditions, the phenolic resin modified with [AeMIM]Br presented the lowest concentration of free formaldehyde and the best mechanical properties, in which the tensile strength and impact strength were improved from 3.28 MPa and 0.93 kJ/m(2) to 9.36 MPa and 5.74 kJ/m(2), respectively, but the hardness only changed slightly.