Study On The Effect Of The Properties Of Heat-treated Toona Sinensis Woods

This paper systematically studied the anatomical properties of Toona sinensis woods and the effects of heat-treated on the chemical properties, physico-mechanical properties and the color of Toona sinensis woods. Andartificial accelerated aging methods is used to assess the resistance of the heat-treated Toona sinensis woods aging. The main findings are as follows:1.With the extension of the processing temperature and time, hemicellulose and holocellulose content fully lowered, acid-insoluble lignin and 1% NaOH extract content was raised. Hemicellulose, holocellulose and mechanized acid insoluble lignin significant ly changedat 200"C, and 1%NaOH extractives significantly changed in critical temperature of 180?, and the effects of heat treatment temperature exceeded the processing time, and the treatment temperature influencedthe processing time. Reusable two-way ANOVA showed that the treatment temperature, time and their interactions were on the content of the heat treated material chemical composition significantly affected.By multiple regression analysis, the loss rate of lignin, hemicellulose and holocellulose content and temperature, time regression model was established, and the R2 values was above 0.76.Based on the scanning electron micrograph, untreated Toona sinensis woods and heat treated material showed that untreated wood catheters and fibroblasts relatively smooth, thin-walled cells intact, but the handling of the catheter material ragged edges, irregular pits larger catheter wall and interconnected,the ray cells and axial parenchyma cells of heat-treated wood was rupture and incomplete.2.Dried density and air dry density of the heat-treated wood increased with increasing temperature and processing time decreased. The critical temperature of the whole dry density and air dry density byheat treatment is 200?, and the effects of treatment temperature was greater than the processing time. With the increase of temperature and time, radial,tangential,volumetric shrinkage rate and air-dry the dry shrinkage rate of Toona sinensis wood decrease, indicating that heat treatment method could improve dimensional stability of Toona sinensis wood. Radial, tangential, volumetric moisture saturated inflation rate,wet and dry gasin inflation rate of Toona sinensis wood were tested downward trend, which showedthat the heat treatment method significantly improved dimensional stability of the wood. Therefore,if only consider raising a separate timber dimensional stability,220"C/6h is the best process parameters.3.With the change of the heat treatment temperature and time, the MOR and MOE ofheat-treated Toona sinensis woodcompared tocontrol material were reduced 1.03% -38.92%.-1.74-20.87%. The critical temperatureof effect of heat treatment on a significantMOR and MOE were 200? and 180?. With the change of the heat treatment temperature and time, the grain compressive strength of heat-treated Toona sinensis wood compared to the control material was reduced in the range of 0.15% -33.84%. With the extension of the heat treatment temperature and time, the decreasing rang of the radial section,tangential sectionend section of hardness of heat-treated Toona sinensis woodrespectivelywere 0.49%-28.92%,0.46%-24.42%,0.65 -21.50%. Considering the costs and problems of loss of mechanical strength,the best treatment technology was 200?/2h.The critical temperature of a significant effectof heat treatment on the wear resistance was 200?, and the single factor analysis of variance showed that the heat treatment temperature on the rate of mass loss wassignificant4.The color of untreated Toona sinensis woodwas reddish yellow, after heat treatment the color gradually depened, from red-brown to red brown, dark brown and finally becomes reddish. With the increasing of the temperature and the processing time,the L* of heat-treated Toona sinensis woodgradually declined.andthe L* of heat-treated Toona sinensis wood compared to the control material was 0.39%-43.81%. The treated Toona sinensis wood was in the development of the black direction. With the extension of time and the temperature riseing,the b*valuesof heat-treated Toona sinensis woodgradually reduced, and the variation of a* is not obvious.The law is substantially reduced after the first rise. The ?E value of heat-treated Toona sinensis wood increases with temperature rise and extension of time rised from 3.75 to 29.33, indicating that the difference between the color change of heat-treated wood and untreated wood, was increasing. By reusable two-way ANOVA analysis showed that the treatment temperature, treatment time and their interactions on L*, b*, a* is very significant.5.The rate of changeof thewhole dry density and air dry density of the control material before and after aging of was significantly greater than the rate of change of the heat treated material, indicating that anti-aging properties of heat-treated Toona sinensis woodwas enhanced. The change of theL*, a*, b*of Heat treated material before and after aging of was less than the change of control the material, which indicated that colorstability of heat treatment material after aging was greaterstable than untreated wood...