Objective Chemical modification of wood was an effective way to improve the mechanical properties, prolong the service life, and broaden the application of fast-growing wood. Wood treated with organo-montmorillonite (OMMT) has a good prospect. However, the difficulty of dispersion of organo-montmorillonite in water as well as the large particle size limited its application. Therefore, improving the dispersion of OMMT in water, simultaneously enlarging its interlayer distance could create conditions for OMMT to enter into the wood cell walls. And also, it was an effective way for wood modification.
Method In this study, a kind of waterborne poly(ethyl glycol) /hyperbranched polyacrylate (PEG/HBPA) emulsion was used as carrier to enhance the water stability of OMMT. The wood was modified by impregnation and the mechanical properties were tested. Besides, the different ions in the interlayers of OMMT on the modification effects were investigated.
Result The four kinds of OMMT all can stably dispersed in PEG/HBPA. After 24 hours of rest, no stratification and precipitation occurred, and the particle size and the viscosity did not obviously change. Wood treated with PEG/HBPA showed improvements on the mechanical properties except for the cross hardness. Incorporation of OMMT can further improve the mechanical properties of wood, and the cross hardness was also improved. OMMT containing amino, hydroxyl and carboxyl groups in its interlayers can be better penetrated into the wood cell walls. Among which, OMMT containing amino groups performed the best. The radial compression strength, flexural strength, and the cross hardness of treated wood reached 82.2 MPa, 98.2 MPa and 8920 N, respectively.
Conclusion Thus, using PEG/HBPA emulsion is an effective way to evenly disperse OMMT. And the OMMT layers can be penetrated into the wood cell walls, improving the mechanical properties, which has a guiding significance on the environmentally friendly and highly-efficient use of fast-growing wood.