| Tectona grandis L.F is an internationally recognized precious species.Its excellent material is often used in high-grade wood products manufacturing,but it is expensive and its natural resources are drastically reduced.There is no distribution of tectona grandis L.F natural forests in China.The plantation range of plantations is wide,but there are different materials and uneven use of wood.Therefore,it is necessary to analyze the wood quality of artificial grapefruit and formulate relevant production processes.The subject of plantation tectona grandis L.F was studied.Firstly,the difference between macroscopic mechanical properties and microstructure and natural tectona grandis L.F wood was systematically analyzed.Secondly,saturated steam softening was used to treattectona grandis L.F.The steaming temperature,treatment time and wood were analyzed based on single factor experiments.The effect of thickness on the bending properties of tectona grandis L.F,combined with the response surface experiment,obtained the optimal process of tectona grandis L.F softening.Then,using superheated steam as drying medium,the influence of medium temperature on the drying quality and elastic recovery of tectona grandis L.F curved parts was obtained.The drying and shaping process of teak curved members was carried out.Finally,based on the softening process parameters of tectona grandis L.F,the effects of steaming temperature and time on cellulose,hemicellulose and lignin in wood chemical components were systematically studied.The change law of the color of the wood after heat treatment.Specifically draw the following conclusions:1)The difference between the macroscopic mechanical properties and microscopic structure of plantation tectona grandis L.F.and natural tectona grandis L.F.wood was systematically analyzed from the perspective of wood science.The analysis shows that the artificial forest teak wood color is lighter and the late wood rate is lower;the wood cellulose content is low,the hemicellulose and lignin content are high;the wood density is relatively small,the strength is lower than the natural forest,and the wood dimensional stability Slightly worse.2)Experimental method was used to soften tectona grandis L.F by saturated steam.The effects of steaming temperature,treatment time and wood thickness on the bending properties of tectona grandis L.F were analyzed based on single factor experiments.The experimental results showed that the bending performance of tectona grandis L.F increased with softening time or temperature.The improvement,and the smaller the thickness of the wood,the better the bending performance of the wood.The optimal optimization interval is steaming temperature 100?140 ?,time 120?240min,wood thickness 15?21mm;on this basis,combined with response surface experiment The optimal process for tectona grandis L.F softening is obtained by linear regression analysis.The optimum conditions for the teak bending softening process are:heating temperature 119 ?,sawn timber thickness 15 mm,softening time 166.67 min.3)Thetectona grandis L.F bent parts were treated with superheated steam as the drying medium.The experimental results show that when the medium temperature is less than 140 ?,the drying condition of the test piece is better with the increase of the drying medium temperature,and there is no large cracking and deformation phenomenon;The rebound rate of the piece gradually decreases as the temperature of the drying medium rises.4)Based on the softening process parameters of tectona grandis L.F.wood,the effects of temperature and time on the cellulose,hemicellulose and lignin in the chemical components of wood were systematically studied,and the variation of wood color after steaming treatment was preliminarily discussed.The experimental results showed that after the steamed teak treatment,the cellulose content increased slightly,and the acid-insoluble lignin content decreased first and then increased.After the teak steaming treatment,the wood color was significantly deepened. |
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