Abstract: [Objective] In order to improve the utilization efficiency of prepolymer of furfuryl alcohol, reduce production cost and promote the industrialization of wood furfurylation, the feasibility of impregnatingly modified wood with prepolymer of furfuryl alcohol(FA-pp)was studied in this paper.[Method] By controlling the mass ratio of furfuryl alcohol monomer(FA-mon)to FA-pp, a homogeneous, stable and water soluble solution for modified wood was prepared by using maleic an hydrideas a catalyst, borax as a stabilizer and water as a diluent. Furthermore, weight percent gain, leach ability, dimensional stability and mechanical properties of modified poplar wood with the mixture of FA-mon and FA-pp were determined, and compared with those properties of FA-mon modified poplar.[Result] When the mass ratio of FA-mon to FA-pp was 35:15, a homogeneous and stable solution of 50% furfuryl alcohol was prepared. Weight percent gain of 90.47% was achieved when poplar wood was impregnated and modified with this mixture solution, which raised 6.41% than that of modified poplar with 50% FA-mon solution. Meanwhile, the leach ability of modified wood with the mixture was 5.27%, which lower 14.17% than that of modified wood with FA-mon. Furthermore, anti-swelling efficiency(ASE)of modified wood with the mixture showed slightly improvements of 4.80%, 1.00% and 2.07% in radial(77.76%), tangential(62.56%)and volumetric(70.02%), compared with that of modified wood with FA-mon. The compression strength parallel to grain of the mixture modified wood(69.93 MPa)substantially increased by 12.55% than that of FA-mon modified wood; but the bending strength(75.86 MPa)and elastic modulus(11.36 GPa)of the mixture modified wood showed a slight decrease than those of FA-mon modified wood. However, when the mass fraction of furfuryl alcohol in the mixture solution deceased to 44%, WPG of wood modified with this solution was nearly same to that with 50% FA-mon solution. Furthermore, the leach ability, ASE values and mechanical properties of the mixture modified wood with 44% solution showed similarity to those of modified wood with 50% FA-mon solution. The analytical result of the infrared spectroscopy showed that absorption peaks of the mixture modified wood were similar to that of FA-mon modified wood. The absorption peaks of furan ring-CH can be seen near to 790 and 735 cm^-1, which proved that the furfuryl alcohol resin had entered into modified wood. Simultaneously, the absorption peaks intensities of hydroxyl near to 3 352 cm^-1 and 1 329 cm^-1 were weakened, and the 1 245 cm^-1 absorption peak became broader and shifted to the right, which indicated that FA-mon or FA-pp formed the chemical cross linking with hydroxyl within modified wood. The analysis result from confocal laser scanning microscopy suggested that furfuryl alcohol resin had entered into the cell lumina, cell walls and middle lamella when wood was treated with the mixture or FA-mon modified solution. Furthermore, the furfuryl alcohol resin in the cell lumina was always presenting on the inner cell walls.[Conclusion] By controlling of the mass ratio of FA-mon to FA-pp, a homogeneous and stable solution for modified wood can be prepared. The main properties of modified wood with the mixture were slightly superior than those of FA-mon modified wood with the same mass fraction of furfuryl alcohol. Furthermore, the mass fraction of furfuryl alcohol with the mixture solution should be less than that with FA-mon solution to obtain furfury lated wood with the similar properties.

Key words: poplar, wood modification, furfuryl alcohol monomer, furfuryl alcohol prepolymer