Study On The Properties Of American Red Oak Introduced With High-quality Wood

In this thesis,the growth characteristics and physical and mechanical properties of three 14-year-old Quercus nuttallii,Quercus nigra and Quercus shumardii introduced from the United States to Nanjing were studied.The research indicators were:fiber morphology,green wood moisture content,growth ring width and basic density,microfibril angle,crystalinity,wood density,dry shrinkage,bending strength,modulus of elasticity,compressive strength parallel to grain as well as impact toughness.Statistical regression analysis and correlation analysis were performed between the indicators.The results showed as follows:(1)The average fiber length,fiber double wall thickness,fiber width,ratio of the lumen diameter to cell diameter and ratio of the double wall thickness to lumen diameter of Quercus nuttallii were 1172.14um,15.86um,10.23um,1.85,0.35,respectively;the average fiber length,fiber double wall thickness,fiber width,ratio of the lumen diameter to cell diameter and ratio of the double wall thickness to lumen diameter of Quercus nigra were 1178.68um,16.56um,11.19um,2.10,0.32,respectively;the average fiber length,fiber double wall thickness,fiber width,ratio of the lumen diameter to cell diameter and ratio of the double wall thickness to lumen diameter of Quercus shumardii were 1162.45um,16.91um,10.96 um,1.91,0.35,respectively.The average moisture contents in green wood of Quercus nuttallii,Quercus nigra and Quercus shumardii were respectively 71.76%,69.79%,and 71.97%.The average growth ring widths of Quercus nuttallii,Quercus nigra and Quercus shumardii were respectively 7.69 mm,7.20 mm,and 7.40 mm.The basic density radial variation range of three American red oak was 0.54g/cm~3~0.69g/cm~3.The average microfibril angles of Quercus nuttallii,Quercus nigra and Quercus shumardii were 33.79°,30.48°,34.10°and the average crystal inity were 51.35%,53.30%,and 52.97%,respectively.(2)The radial variation of fiber length,basic density and crystallinity was:increased from the pith to outward,and the radial variation of the microfibril angle showed a downward trend from the pith to outward,which has not stabilized.Three American red oak were still juvenile tree.(3)The air-dried densities of Quercus nuttallii,Quercus nigra and Quercus shumardii were0.72g/cm~3,0.75 g/cm~3 and 0.77 g/cm~3,respectively;the oven-dried densities were respectively0.69 g/cm~3、0.71 g/cm~3 and 0.73 g/cm~3;the basic densities were respectively 0.58g/cm~3、0.61g/cm~3 and 0.62 g/cm~3;the radial oven-dry shrinkages were 4.34%,4.21%and 4.33%,respectively;the tangential oven-dry shrinkages were 11.47%,9.95%and 10.95%,respectively;the volume oven-dry shrinkages were 11.47%,9.95%and 10.95%,respectively;the radial air-dry shrinkages were 2.02%,2.47%and 2.59%,respectively;the tangential air-dry shrinkages were 7.14%,6.85%and 7.68%,respectively;the volume air-dried shrinkages were 9.35%,9.76%and 10.62%,respectively;the ratios of tangential shrinkage to radial shrinkage at oven-dried condition were respectively 2.65,2.38 and 2.60;the shrinkage coefficients were 0.57,0.52 and 0.56,respectively.(4)The compressive strengths parallel to grain of Quercus nuttallii,Quercus nigra and Quercus shumardii were 52.72 MPa,45.57 MPa and 54.44MPa,respectively;the bending strengths were 99.44 MPa,102.90 MPa and 103.62 MPa;the modulus of elasticity were 7.70GPa,7.60 GPa and 7.04 GPa;the impact toughness were 215.80 KJ/m~2,217.56 KJ/m~2 and 241.84KJ/m~2.(5)Correlation analysis between traits:there is a significant or extremely significant correlation between growth width of Quercus nuttallii,basic density of growth ring,fiber morphology parameters,microfibril angle,crystal inity,air-dried density,radial oven-dried shrinkage,tangential oven-dry shrinkage,volume air-dried shrinkage,ratio of tangential shrinkage to radial shrinkage and bending strength,modulus of elasticity,impact toughness;there is a significant or extremely significant correlation between basic density of growth ring of Quercus nigra,fiber morphology parameters,microfibril angle,air-dried density,radial oven-dried shrinkage,tangential oven-dry shrinkage,volume air-dried shrinkage,ratio of tangential shrinkage to radial shrinkage and bending strength,modulus of elasticity;there is a significant or extremely significant correlation between basic density of growth ring of Quercus shumardii,fiber morphology parameters,tangential oven-dry shrinkage,volume air-dried shrinkage and bending strength,modulus of elasticity.(6)The fiber morphology parameters of Quercus nuttallii,Quercus nigra and Quercus shumardii were moderate in the woods of Quercus spp.The physical properties of three American red oaks were close to Quercus liaotungensis and Quercus mongolica.Compared with several woods of Quercus spp,Quercus nuttallii,Quercus nigra and Quercus shumardii has greater impact toughness and smaller modulus of elasticity.