| Poplar is a common man-made tree species,which has advantages of fast growth and wide distribution,can alleviate the problem of timber supply and demand in our country.But poplar has some defects,for instance,characteristics like a lack of density,inadequate strength,and subpar dimensional stability hinder its market usage.However,a cost-effective,eco-friendly modification technique utilizing heat treatment,heat treatment and wax impregnation can ameliorate the aforementioned issues.It enhances poplar’s mechanical properties,dimensional stability,anti-UV aging properties,and surface contact angle,thereby providing a theoretical foundation for enlarging poplar’s market application and facilitating the production and utilization of modified wood in the furniture industry.Firstly,this study started from the polyethylene wax vacuum impregnation process of poplar.Through the orthogonal test of vacuum degree and vacuum time,the optimal polyethylene wax vacuum impregnation process of poplar was obtained,which provided the impregnation process for the combined treatment of heat treatment and wax impregnation.Secondly,four heat treatment temperatures of 140℃,160℃,180℃and 200℃,three heat treatment times of 1h,2h and 4h were used to carry out physical,mechanical and application properties of heat treatment and wax impregnation wood.The influence of different heat treatment temperatures and time was explored.The mechanism was analyzed by Fourier transform infrared spectroscopy and X-ray diffraction.Finally,according to the properties and colors of the modified wood,a set of solid wood furniture for young people is designed.The main conclusions are as follows:(1)The optimal vacuum process of polyethylene wax impregnated poplar:vacuum degree-0.1MPa,vacuum time 2h.After vacuum impregnation,the total dry density of poplar was0.82g/cm~3,which was 44.53%higher than that of untreated wood,and the weight gain rate was83.64%higher than that of untreated.The transverse section observed under scanning electron microscopy showed that the cell cavity of poplar was almost filled with polyethylene wax.(2)When the temperature and time of heat treatment increased gradually,the total dry density of poplar after heat treatment showed a decreasing trend,and the weight loss rate showed a gradually increasing trend,which was proportional to the treatment temperature and time.Temperature has stronger influence on total dry density and weight loss than time.After heat treating and wax impregnation,the total dry density of poplar decreased first and then increased,and the weight gain rate gradually increased,and the total dry density of poplar was higher than that of untreated and heat treated.Therefore,the total dry density of poplar after heat treatment and wax impregnation is better than that after single heat treatment.(3)Heat treatment,heat treatment and wax impregnation can reduce the dry shrinkage rate and wet expansion rate of poplar,there is a significant enhancement in dimensional stability.At medium and high temperature,the radial,chord,volume dry shrinkage rate and wet expansion rate decreased significantly.The heat treated ones exhibited enhanced dimensional stability of heat treated and wax impregnated materials was superior to that of solely heat treated materials,and the dimensional stability of combined modified materials was better than that of materials treated solely with heat.4)The color of the heat treated material changes from light beige to brown on the whole,and the color of the heat treated and wax impregnated material changes from dark beige to dark brown.The color deepening is not obvious between 140℃and 160℃,but the deepening degree is obvious after 180℃.With an increase in the heat treatment temperature,the brightness L*of the heat-treated and wax-impregnated materials gradually decreased,while the color difference?E increased.The influence of temperature was more pronounced than that of time,and the effect on the value a*was greater than that of value b*.(5)After heat treatment and heat treatmen wax impregnation,the flexure strength and elastic modulus of poplar increased at 140℃～180℃,and decreased at 200℃.The impact toughness of heat treated materials decreases as the temperature and duration of heat treatment increase,wax impregnated materials shows an increase followed by a decrease.Wax impregnated materials at140℃～180℃is higher than that of untreated,which indicates that the mechanical loss of heat treatment can be compensated.In general,the mechanical properties of heat treatment combined with wax impregnation are better than that of single heat treatment.(6)Both heat treatment and heat treatment and wax impregnation can increase the water contact Angle of poplar,and the water contact Angle of heat treatment and wax impregnated wood is larger than that of heat treated.The color difference?E is reduced after ultraviolet aging,which indicates that the two modifications are effective,but not all the heat treatment temperature is higher,the heat treatment time is longer,the heat treatment material,heat treatment and wax impregnation material can prevent a certain UV light.(7)Fourier transform infrared spectrum showed that the whole peak position of the treated poplar was similar to that of the untreated,and there was no great change.The heat treatment and wax impregnated wood showed a new peak,namely the characteristic peak of polyethylene wax,which indicated that polyethylene wax was successfully impregnated into poplar and reacted with cellulose,hemicellulose and lignin to improve dimensional stability and mechanical properties.Heat treatment temperature and time do not change the location of poplar 002diffraction peak,and have no effect on the distance of crystal layer in the crystallization zone.The temperature and time of heat treatment have influence on the crystallization zone of poplar.(8)Based on the properties of poplar wood’s heat treatment,For instance,the color,mechanical characteristics,and heat treated dimensional stability of wax impregnated materials,a set of poplar furniture for young people is designed.With modern design methods to provide a modified wood furniture design ideas,so that consumers are no longer unfamiliar with poplar modified furniture,but also for the furniture industry into new blood. |
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