Synthesis Of Organosilicon Polymer And Its Application In Wood Waterproofing Modification

Wood is a kind of biomass material with hygroscopicity and hydrophilicity,which is prone to deformation,discoloration or decay degradation due to the influence of water.Therefore,it is necessary to improve the use value of wood by waterproof modification.In this paper,sodium silicate and vinyl triethoxysilane(VTEs)were used as organosilicon polymer precursors to prepare wood waterproof agent.The reaction mechanism of organosilicon polymer was studied by near-infrared(NIR)spectroscopy and two-dimensional correlation analysis(2DCorr)to obtain the optimum ratio and action time of organosilicon polymer,and the hydrophobicity of water repellent on wood surface was observed.In addition,the organosilicon polymer was blended with epoxy resin,and copolymerized with acrylic resin using semi-continuous monomer dropping seed emulsion polymerization process respectively.Then,the wood surface was brushed and impregnated by the composite resin respectively.Finally,the properties of modified wood such as hydrophobicity,water repellency and dimensional stability were tested to investigate the waterproof effect of modified wood,and the surface chemical structure of modified wood was observed by attenuated total reflection Fourier transform infrared spectroscopy(ATR-FTIR).The results are as follows: 1)With the increase of the ratio of VTES,the free hydroxyl group and alcohol hydroxyl groups decrease while the combined hydroxyl groups increase,and the silicon-containing groups increase as well;The optimum molar ratio of the mixed solution is 1:5.With the increase of time,more and more hydroxyl groups are combined by hydrogen bonds;The advanced overtone transition is difficult for C-H group;The hydrolysis and condensation reactions fully occur in the mixed solution within 2 h.The contact Angle of brushed modified wood surface is 114° with a certain hydrophobicity.2)The sequence of group variation with perturbation was revealed by two-dimensional correlation near-infrared spectroscopy.It is found that with the increase of VTESratio,hydroxyl groups are combined by hydrogen bonds gradually;The hydrolysis reaction occurs after the addition of siloxane to form silanol.With the increase of time,the C-H group is more sensitive to the change of time than the bound hydroxyl group and the silicon-containing group,which is difficult to occur the advanced overtone transition;Si-O-C group generates Si-OH and Si-O-Si groups by hydrolytic and condensation reactions,which changes prior to the latter two groups;The Si-OH combination band occurs after it's overtone band;The orientation of Si-OH and Si-O-C excited dipole moment occurs simultaneously.3)After the modification of wood by silicon-acrylic resin,it is found that the hydrophobic effect of brushed and impregnated processing wood is better than that of the organosilicon polymer modified wood,and also better than that of the modified wood with silicone-containing epoxy resin,in which the hydrophobic property of the brushed processing wood is more remarkable;Infrared spectroscopy has found that the hydroxyl groups on the surface of untreated wood are shielded,thereby reducing the moisture absorption capacity of wood,and the brushed processing wood contains more chemical groups with low surface free energy;The water repellency of impregnated treated wood is better than that of untreated wood,and anti-shrinkage performance decreases in the later stage while anti-swelling performance is stable all the time.4)After the modification of wood with silicon-containing epoxy resin,it is found that the hydrophobic effect of the impregnated wood is better than that of the brushed wood,which is slightly improved compared with the modified wood with organosilicon polymer;Infrared spectroscopy has found that the hydroxyl groups on the surface of untreated wood are shielded,thereby reducing the moisture absorption capacity of wood,and the impregnated processing wood contains more chemical groups with low surface free energy;The water repellency of brushed and impregnated processing wood is better than that of untreated materials,and anti-shrinkage performance is stable all the time while anti-swelling performance decreases in the later stage.In general,the water repellency and dimensional stability of the modification wood by silicon-containing epoxy resin are better than that of silicone acrylic resin modified wood,and impregnated treated wood has better waterproof performance.