Study On The Synthesis Of Functionalized Ionic Liquids And Modification On Phenolic Resin

Five functionalized halogenated imidazolium ionic liquids, include three short chain ionic liquids of 1-(2- hydroxyethyl)-3- methyl imidazole chloride([HeMIM]Cl), 1- ethylamine-3-methyl imidazole bromide([AeMIM]Br) and 1- carboxy ethyl-3- methyl imidazole chloride([CeMIM]Cl) and two polyether ionic liquids of hydroxyl-terminated polyether imidazolium ionic liquid([HO-PECH-MIM]Cl) and carboxyl-terminated polyether imidazolium ionic liquid([HOOC-PECH-MIM]Cl) were synthetized and their chemical structures were characterized by FTIR and HNMR. The synthesized ionic liquids was in situ blended with phenol, formaldehyde or with phenolic prepolymer directly to produce phenolic resin composites, then the effects of structural characteristics of ionic liquids on mechanical properties, thermal properties and free formaldehyde of phenolic resin composites were studied. The short chain ionic liquids were used to dissolve biomass(wood powder, straw, corn stalk), then blended with phenolic prepolymer to produce phenolic resin composites, the effects of solubility of ionic liquids and biomass on mechanical properties, thermal properties,curing properties and free formaldehyde of phenolic resin composites were studied.The results showed that the synthesized ionic liquids were the target products which had higher purity, The yield of short chain and polyether ionic liquid were higher than 93% and75% respectively. The mechanical properties of phenolic resin modified by short chain ionic liquids were improved obviously, the tensile /impact strength of phenolic resin composites modified by [AeMIM]Br were the best, increased from 3.28 MPa and 0.93KJ/m2 to 9.70 MPa and 6.06KJ/m2, while the free formaldehyde content of phenolic resin composites reduced from 3.64% to 2.46%, the hardness only changed slightly, but thermal stability decreased slightly. The tensile /impact strength of phenolic resin composites modified by polyether ionic liquids increased to 6.94 MPa and 9.51 MPa and the free formaldehyde content of phenolic resin composites reduced to 0.14%, which showed that the functionalized ionic liquids could reinforce and toughen phenolic resin and reduce effectively the content of free formaldehyde,the toughening effect of polyether ionic liquids was obviously higher than short chain ionic liquids. The results of modification with biomass dissolved in short chain ionic liquids showed that ILs present good solubility toward biomass, increasing the temperature resulted in anincreased dissolution rate, in which the solution of [CeMIM]Cl for biomass was the best and the dissolution rate were up to 24.6% when solution temperature was 90℃. The properties of phenolic resin composites modified by short chain ionic liquids dissolved biomass were improved obviously. with the increase of the amount of ionic liquid, the performance of phenolic resin composites was perfected gradually, when the weight ratio of ILs to the biomass exceeded 20:1, the properties of phenolic resin composite tented to be stable, in which the mechanical properties of phenolic resin composite modified by [AeMIM]Br dissolved biomass was obviously higher than [CeMIM]Cl and [HeMIM]Cl. Compared with phenolic resin composite modified by short chain ionic liquids directly, that of modified by ILs and biomass could be further improved and the content of free formaldehyde can be significantly reduced,which showed that the biomass raw material could not only reduce the cost of phenolic resin,but also enhance the phenolic resin and capture the free formaldehyde. The above research showed that phenolic resin could be reinforced by ionic liquids and the content of free formaldehyde can be significantly reduced, the phenolic resin composite were in conformity with the research idea of high performance, environmental friendly polymer materials.