The Research Of The Synthesis Of Composite Wood Modifier And Its Enhancement Mechanism

As the manual mill resources growing, how to solve its applicable scope is small, low added value has become a worldwide problem. In order to understand the modification process, the study firstly focuses on the anatomic structure of fast-growing poplar wood, the specific mechanism of in-situ gel polymerization by using DMDHEU, silica sol, and other catalysts in wood cell wall is illustrated.In this study, silica sol was introduced into the system to conduct the process of "sol-impregnation-gel-polymerization". First, the solvent was adjust into acid condition, then gel will largely happened in the wood micropores. The group of Si-OH could form H-bond with the group of-OH in methylolurea. The gel forming in the wood micropores will help keep the whole system be much more stable.Then the heat in drying air dry oven induced the in-situ gel polymerization. CP/MAS 13C-NMR analysis has shown that chemical reactions mainly happened in the C6 of amorphous region cellulose; XPS analysis showed acetic acid derived from hemicelluloses during the heating process, then esterification happened; FTIR spectra showed that reactions occurred between the wood-OH, Si-OH, and DMDHEU-OH to form C-O-Si and C-O-C bonds. It was demonstrated by XRD that silica sol crystallized within the interfibrillar region of the cell wall, but the cellulose in wood was not significantly influenced by this modification. All above chemical reactions help the treated wood acquire the better dimensional stability (MOD decreased by 39%) and mechanical properties (bending strength increased by 63.1%; compressive strength parallel to grain increased by 16.4%). On one hand, this result partly due to gel forming (the density of wood increased from 0.41g/cm3 to 0.68g/cm3).