| Machilus versicolora S.Lee is one of the evergreen tree of Lauraceae family,whose trunk is straight and round.It has been one of the highest economic value species of hardwood in Fujian Province and enjoyed by the masses to be the species for afforestation and timber.However,up to now the study on properties of M.versicolora hasn't been reported in the domestic and foreign.The properties of M.versicolora it's a fundamental issue to be proved urgently from the theoretically and production aspects for oriented cultivation and rational utilization.M.versicolora was used as the research object in this paper to determine and analyze its construction characteristics,chemical properties,physical and mechanical properties,surface characteristics and painting properties,durability and antibacterial effects of extracts and so on.The study reveals the properties of M.versicolora systematically,which will provide a theoretical basis and basic data for oriented cultivation and rational utilization.The main results about M.versicolora wood were obtained as following:(1)There were circular lenticels on the bark.Wood table appeared ribs.Wood structure was fine to medium and its texture was soft.Wood had luster and light aromatic odor.There were no significant difference between heartwood and sapwood and its color was fawn.The growth rings were obvious,while circular to elliptical.The ring width was non-uniform and there was a light-colored band between the rings.It was diffuse-porous wood,slightly less number of pores,medium and visible to perspicuity,evenly distributed.Axial parenchyma were visible under the naked eye as ring canal bundle and sparse sidewise tubular.Wood ray were also visible under the naked eye and ray speckle could be seen on the radial section.Ripple marks and intercellular canal were absence.The cross section of vessel was circular,oval and polygonal section with contour.The pores were mainly pore solitary and short diameter multi-celled pore chains(usually 2 to 4),occasionally pore clusters.The vessel moleculars were mainly to be cylindrical and spindle shape,a small portion of the vessel had tylosis.Intervessel pitting alternated and its pit port appeared connotation and outreach,partially connate,lens-shaped and oval-shaped.Scalariform pitoccasionally appeared.Perforation vessel had simple perforation plate while the plate tilted significantly,scalariform perforation occasionally appeared.Axial parenchyma were mainly ring canal bundle,occasionally sparse sidewise tubular while oil cells or mucus cells were common.The pit on the axial parenchyma cell were simple pits with all connotation,round and oval shape.Wood fiber appeared long spindle shape with tip shave at two ends,large cavity and the wall thin to a little thin.The average length,width,ratio of length to width,lumen diameter,double wall thickness and ratio of wall thickness to lumen diameter of wood fiber was 1298.52?m,38.47?m,34.50,23.95?m,9.67?m and 0.42 respectively.Septate wood fibers were visible and the type of the pit on its wall was the same to the vessel.Wood rays were non-storied,generally type ? or ?.Single rays rarely appeared,which owned 2 to 8cells height while multiple columns ray were common,which owned width 2-3 cells(mainly two)width,4 to 39 cells(most 8 to 27 cells)height.The pits between ray and vessel were oval,gashes(row),partly similar to vessel.The type of the pit on the wall of rays was the same to the axial parenchyma;Oil cells or mucus cells were fewer.Intercellular canal were absence.(2)The contents of cellulose,pentosan,lignin and holocellulose of M.versicolora were 47.22%,19.19%20.57%and 71.89%respectively.Content of hot water extract,alcohol benzene extract and 1%NaOH extractive from M.versicolora wood was 10.95%,3.76%and 21.8%respectively.Ash content was 0.55%and pH value was 5.63,which was slightly acidic.There were some differences in the chemical composition between M.versicolora,Machilus kwangtungensis and Phoebe bournei.20 kinds of chemicals were identified by GC-MS from the extracts by methanol and chloroform.There were 8 species in extracts by methanol and 12 species in extracts by chloroform,which the component percentage of were 78.43%and 39.97%in extracts by methanol and chloroform respectively.(3)The basic density of M.versicolora was 0.361?0.581g/cm3 and the air-dry density was 0.494g/cm3,which was medium partial low.From pith to bark,the basic density was gradually increasing first,then tended to be stable.The wood tended to steady state full of water after immersion in water for more than 40d while its water absorption was 176.3%and satisfies the equation with absorption time:y=167.880-115.866*0.711X.The tangential and radial shrinkage coefficients were 0.26%and 0.13%and the volume shrinkage coefficient and ratio of tangential shrinkage to radial shrinkage were 0.42%and 1.97,which indicated that M.versicolora had good dimensional stability.The compressive strength parallel to grain,bending strength and modulus of elasticity were 45.3MPa,143.1MPa,10700MPa,which belonged to high grade.Tts comprehensive strength was 188.4MPa,which showed that M.versicolora was the high-strength wood.The strength quality coefficients was 3829.3×105Pa,which showed that M.versicolora was the high-grade wood.The hardness of cross section,tangential section and radial section were 3710N,3590N and 3490N respectively,whose hardness of cross section belonged to lower hardness level,so it was easy to cut.(4)The color of M.versicolora wood was:L*:67.04?68.86,a*:1.87-2.52,b*:15.25?17,59,V:5.56?5.74,H:7.02Y?7.67Y,C:3.24?3.62,which indicated that it was a species of smarter,middle-saturation,reddish yellow.The gloss of parallel to the wood grain was 2.29?3.63 gloss units,while the perpendicular was 2.00?2.88 gloss units.Surface free energies of M.versicolora wood was large(more than 70mJ·m-2),which had a good surface wetting properties.The contact angles of M.versicolora wood were quite different by different solvents and under different granularity sandpaper treatment while the ?-t curve became smaller with the time increasing.With the sandpaper count increased,the surface roughness after sanding became smaller,such as Ra:4.51?5.63?m,Rz:45.72?49.82?m,Rsm:0.15?0.20mm,and the variation of Rz was complex.After painting,the L*was decreased,and it belonged to a high saturation of red and yellow hue dominated.The painting had less affected to the wood color of M.versicolora.The surface gloss was increased after painting and different processing granularity sandpaper had different magnitudes.The gloss ratio decreased after being painted by alkyd varnish,while it increased after being painted by polyurethane varnish.The gloss value of alkyd varnish was greater than polyurethane varnish.The painting properties of alkyd varnish were better than polyurethane varnish,and both were good painting performance.(5)The natural decay resistance of M.versicolora wood against Coriolus versicolor met the demand of degree I,which showed strong resistance to fungal decay,however the natural decay resistance of M.versicolora against Gloeophyllum trabeum met the demand of degree III,which showed slight resistance to fungal decay.The SEM observation analysis showed that brown rot fungus had a large damage to M.versicolora wood,mycelium went into the interior through the pits,it eroded wood subject to a certain degree.The mycelium of white rot fungus just distributed on the surface and did not enter the interior,so the structure was relatively intact.FTIR method was used to comparatively analyze the change of major functional group,the result showed that brown rot fungi mainly degraded cellulose and hemicellulose of wood,while white rot fungi mainly degraded lignin of wood.XRD analysis showed that corruption didn't change the crystal structure of the fiber,but changed the degree of crystallinity.TG-DSC analysis showed that the pyrolysis was divided into four stages:drying,preheating,rapid weight loss,calcination,the third phase appeared the hemicellulose and cellulose pyrolysis thermal decomposition,and the fourth stage appeared lignin thermal decomposition.DSC curve showed the same trend before and after the decay,but the maximum exothermic and endothermic reaction temperatures after decaying were shifted to higher temperature,which may be associated with the formation products after wood decay fungi degradation.(6)There was positively correlated between the antifungal effects on the concentration of different solvent extracts of M.versicolora wood and wood-rotting fungi.The order of antifungal activity of different M.versicolora wood extracts against C.versicolor was:chloroform extracts,ethyl acetate extracts,methanol extracts,acetone extracts,and that against G.trabeum was:methanol extracts,acetone extracts,ethyl acetate extracts,chloroform extracts,which showed that chloroform extracts had the best antifungal effect on C.versicolor while methanol extracts had the best antifungal effect on G.trabeum.The mainly chemical composition of antibacterial activity of methanol extracts were terpenes,ketones,phenols and esters while the chloroform extract were triazines,amides,phenols,aldehydes and other compounds. |
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