Study On Wood Fiber And Wood Surface State On The Effect Of Bonding Performance Of The Eucalyptus Grandis×E.urophylla

Eucalyptus grandis × E.urophylla is one of the eucalyptus species planted in large area in Guangxi plantation,it has excellent properties.If we can further understand the nature of Eucalyptus grandiflora wood,it is of great significance to wood and its glued products.In this study,the fiber morphology indexes,some wood mechanical strength indexes,and the bonding strengths of different blanks and different surface roughness wood veneers were studied,and the changes of functional groups at the interface were characterized.The results of the study are as follows.(1)The average fiber lengths of three-year-old,five-year-old and seven-year-old Eucalyptus grandis × E.urophylla were 824.50?m,878.40?m and 911.00?m,respectively;The average fiber width was 17.36?m,17.93?m and 17.56?m,respectively;The fiber aspect ratios were 47.38,49.44,and 52.59,respectively;The average fiber double wall thicknesses were 6.87 ?m,7.10 ?m,and 7.48 ?m,respectively;The average fiber lumen diameters were 10.49 ?m,10.82 ?m,and 10.08 p.m,respectively;The average ratios were 0.696,0.692,and 0.82,respectively.(2)The average values of the compressive strength of the three-year-old,five-year-old and seven-year-old Eucalyptus grandis×E.urophylla were 48.83 MPa,57.48 MPa,and 60.16 MPa,respectively;The average flexural strength was 88.79 MPa,99.62 MPa,and 105.98 MPa,respectively;The average values of modulus were 8888.26MPa,10300.79MPa,and 11324.64 MPa,respectively;The average values of impact toughness were 31.30 kJ/m2,40.38 kJ/m2,and 44.73 kJ/m2,respectively;The average veneer bonding strength was 0.98 MPa,1.04 MPa,and 1.11 MPa,respectively.The veneer's bonding strength and the above indicators all increased with age.(3)In the wettability of Eucalyptus grandis x E.urophylla wood veneers,the wettability of the 320 mesh treatment group was the worst,and that of the 36 mesh treatment group was the best.Tight-faced surface wettability of veneers,the wettability of the untreated group was the worst,and the wettability of the 36-mesh treatment group was the best.When the mesh number and surface mesh number interact,the initial contact angle and the equilibrium contact angle of the Eucalyptus grandis wood veneer surface have a significant influence,while the initial contact angle and the balanced contact angle of the veneer surface are not affected.The average value of the initial contact angle of the loose panel is larger than that of the tight surface,and the average value of the contact angle of the tight surface is greater than that of the loose panel.(4)The Ra,Ry and Rz values of the horizontal stripes and the smooth stripes on the loose and tight surfaces of the Eucalyptus grandisx E.urophylla were gradually reduced with the increase of the number of sandpaper meshes;In the results of analysis of variance,the surface*mesh number have significant influence on the values of Ra,Ry,and Rz,while the surface mesh interaction has no significant effect on the three values;The results of different surface multi-tests showed that the average values of Ra,Ry,and Rz of the striated surface and horizontal stripes were larger than those of the tight surface;and the ordering of the three factors was satisfied:36 mesh treatment group>untreated group>100 mesh>320 mesh>600 mesh>1000 mesh>1500 mesh.(5)The bonding strength of the three-layer plywood wet board is the largest in the 1500-mesh treatment group and the smallest in the 36-mesh treatment group.In the dry board bonding strength,the 100-mesh treatment group is the largest and the 36-mesh treatment group is the smallest;The wet board bonding strength of the tight surface x tight surface assembly was the largest in the untreated group and the smallest in the 320 mesh treated group;Different surface treatments have significant effects on the dry and wet bonding strengths of the three kinds of slabs,namely the tight surface x the tight surface,the tight surface x the loose surface and the loose surface x the loose surface,and the three-layer plywood.In the comprehensive analysis of the bonding strength of two-layer plywood,there are significant effects on the wet and dry bonding strengths in the three interactions of the blank,the mesh number and the blank*mesh number;In the wet bonding strength,the mean size is:tight surface x tight surface>tight surface×loose surface>loose surface x loose surface;in the dry bonding strength,the mean size is:tight surface x tight surface<tight surface×loose surface<loose surface x loose surface;(6)There is no significant difference in the content of components between different ages of eucalyptus.In the process of hot-press bonding,urea-formaldehyde resin reacts with cellulose,hemicellulose,and lignin on the surface of the veneer to form a glue.The intensity of the lignin peak was significantly affected by pressure.Different surface treatments had little effect on the functional groups on the surface of eucalyptus,but compared with the untreated group.Absorption vibration peaks of the hydroxyl group near the wave number of 3338cm-1 shifted to the left;near the wave number of 3447cm-1,the characteristic peak of the 320 mesh treatment group was the strongest.