Study On The Modification Of The Bonding Interface Of Fast-growing Masson Pine Wood

The bonding and coating properties of wood are closely related to its interface properties.In this study,fast-growing Pinus massoniana wood was used as the research material.Traditional modification methods(heat treatment,alkali treatment)and new modification methods(plasma treatment)were used.The surface wettability,chemical groups,surface morphology and crystallinity of Pinus massoniana wood were analyzed by contact angle measuring instrument,infrared spectrometer,scanning electron microscope,X-ray photoelectron spectroscopy,thermogravimetric analyzer,and so on.By comparing the bonding strength and water resistance of Pinus massoniana glued wood,the influence of different treatment methods on the surface properties of Pinus massoniana was explored,and the bonding mechanism of different treatment methods was revealed.The results are as followed:(1)With the increase of heat treatment temperature,the color of wood gradually deepened to black;The crystallinity of cellulose increased;The surface wettability of Pinus massoniana treated at160-180 ? was better,but the surface treated at 200-220 ? was hydrophobic;The results show that the surface becomes rough,the oil particles decrease,the porosity increases,and the edge of pits collapses and shrinks gradually;The coarseness of wood surface and the change of porosity and wettability lead to the decrease of bonding strength and bonding reliability of Pinus massoniana glued wood.(2)Alkali treatment can change the color of wood into light yellow,increase the crystallinity of cellulose,improve the wettability,effectively reduce the grease in resin channel of Pinus massoniana,and open the pores blocked by grease;However,alkali treatment will change the internal structure of Pinus massoniana wood,oil spillage on the surface of wood and other negative factors,resulting in the diffusion and penetration of adhesive on the surface of wood,and the formation of glue nails in the wood,so that the curing of adhesive on the surface of wood is uneven and insufficient,and the bonding strength of Pinus massoniana wood is reduced.(3)Plasma treatment will not change the color of wood;The high energy particles in the plasma have physical and chemical effects on the surface of Pinus massoniana wood at the same time,which degradates the grease on the surface,and the hydroxymethylation reaction occurs between the cellulose molecular chains in the amorphous region of cellulose,which makes the arrangement of microfibrils in the non crystalline region more orderly and improves the crystallinity of cellulose;The micro etched rough surface was formed on the surface of wood,which produces a large number of polar groups,increases the surface dispersion force and polar force,and improves the bonding strength of wood.In summary,heat treatment and alkali treatment can make the surface of Pinus massoniana rough,but it is only macroscopic rough,which was conducive to penetration,but not necessarily conducive to gluing.Plasma treatment makes the surface rough,which is microscopic rough,which is conducive to penetration and gluing;Heat treatment and alkali treatment can deepen the color of wood and affect the aesthetic consistency of wood,while plasma treatment has little effect on the color of wood;Heat treatment and alkali treatment are permanent changes in the internal structure of wood,changing the chemical composition of the wood surface at the same time,its own strength will be affected.Because of its timeliness,plasma treatment only temporarily increases the active groups on the surface of wood,and does not change the internal structure of wood,it will not affect the strength of wood itself.Plasma treatment can significantly improve the bonding strength and stability of Masson pine.It was a kind of modification method which can improve the bonding strength of Masson Pine surface and protect the environment.