Study On Surface Plasma Treatment Of Wood With High Temperature Heat Treatment

There will be cracking,deformation and decay,making the product quality can not be guaranteed in the process of using wood materials.After high temperature heat treatment,wood moisture absorption characteristerics,corrision and dimensional stability are improved effectively.It also makes the wood internal decompositon of cellulose and hemicellulose,and the wettability,the bonding strength are reduced.However,the plasma surface treatment technology can effectively enhance the wettability of wood.With the development of plasma treatment,its application in wood surface modification is becoming more and more extensive.Its treatment time is short,the efficiency is high,and the energy consumption is low,and it is a kind of technology which develops most quickly in many material modification methods.Plasma treatment has very broad application prospect,and the present research has made some progress.In this experiment,high temperature heat treatment(carbonization)of birch wood(Betula costata Trautv.),white wax wood(Fraxinus excelsior.)and cherry wood(Prunus serotina.)were used as raw materials,and nitrogen and oxygen were used as processing gases,the power,time and pressure of plasma treatment as variables,and to study the effects of three kinds of wood with different processing parameters.The experiments were characterized bycontact angle,X-ray photoelectron spectroscopy(XPS)and bonding strength to characterize the property changes of three species of wood that occured before and after plasma treatment,and the micro morphology was characterized by scanning electron microscopy(SEM),atomic force microscopy(AFM).The contact angle is used to characterize the wettability of the wood surface.After plasma treatment,it is found that the treatment effect of nitrogen is better than that of oxygen.When the treatment power was 80 W,30s,and 40 Pa,after 8d,the contact angle of birch was 22.2°,decreased77.74%;white wax basically equal to the level before treatment after 8d;while cherry was 34.43°,decreased 68.69%.XPS test results showed that after plasma treatment,the O/C ratio was obviously increased,the nitrogen treatment effect of birch was better,the oxygen treatment effect of cherry wood was better,and for white wax,after two kinds of gas treatment O/C was almost at the same level.In the XPS analysis results,a new C-N peak appeared in the nitrogen-treated sample,that was,a new hydrophilic group was introduced,and the surface chemical composition changed to some extent.This was also an important cause of the rise in hydrophilicity the surface of the wood after plasma treatment.The results of scanning electron microscopy and atomic force microscopy showed that after the plasma treatment,the surface morphology of the wood had changed significantly,the roughness of all the three kinds ofwood had increased,the result of oxygen treatment of birch was more rougher.But the treatment effect of two gases of white wax wood was not obvious.For cherry wood,the etched degree of nitrogen was much better than that of oxygen treatment.The roughness was greatly improved,and the adsorption capacity of the adhesive and the paint film will be greatly helpful.The heat treated wood was tested for the bonding strength after plasma treatment.The birch and white wax did not increase in the nitrogen atmosphere,and even decreased slightly,while the cherry rose from 5.81 MPa to 6.43 MPa,with an increase of 9.64%.After oxygen treatment,the bonding strength of birch,white wax and cherry wood increased by 22.65%,35.27% and 24.96%,respectively.The effect of oxygen treatment was much better than that of nitrogen.At the same time,the experiment also tested the changes of surface wettability of the three species of wood after plasma modification over time,which was basically at about 8d.The effect within the first 2d after modification was the best,during which the glue was applied,the results will also be ideal.