Study On Compression Structure Of Inferiority Fast-Growing Wood

According to preliminary study on E.grandis×E.urophylla ,Cunninghamia lanceolata and Populus nigra L wood compression. close to the best compression parameters.and then, According to the best compression parameters directly to E.grandis×E.urophylla, Cunninghamia lanceolata, Populus nigra L wood from the compression ratio by 20%～60% compression. Stereomicroscope and digital microscopy were used to the specimens which aren't compressed and the specimens which are compressed overall and the slice observes and measurement. after the quantitative analysis,obtains the ratiorelations of the cell porosity and the compression ratio, using the scanning electronmicroscope to observe the cell walls and pits of the specimens which aren't compressed and the specimens which are compressed,analyzes its microscopic structure change, draws following conclusion:1．In the course of compressed, the fixation of compressed wood is mainly rely on the amount of hydraxyl decrease, crystallization and hot decomposition and crosslink reaction in cell wall's composition. Microstructure analysis from compressed wood, from the specimens which aren't compressed to the specimens which compression ratio 30%, the cell porosity of vessel element of E.grandis×E.urophylla and Populus nigra L decreased by 9．5 % and7．82 %, the cell porosity of wooden fiber only decreased by 3．72 % and 3．26 %.on compression rate from 30% to 60%. the cell porosity of vessel element of E.grandis×E.urophylla and Populus nigra L decreased by 9．94 % and7．42%. the cell porosity of wooden fiber decreased by 7．13 % and3．48%. Indicated , the vessel elements is easier to be compressed than the wooden fiber cells, thus it can be seen E.grandis×E.urophylla and Populus nigra L wood in compression process, the cells involved in the sequence : thin cells-vessel elements-wooden fiber cells;Cunninghamia lanceolata wood: early tracheid be compressed-late tracheid in the evening compression.2．E.grandis×E.urophylla and Populus nigra L wood at 50%, compression ratio and porosity relations curves emergence of a turning point. the relations between the compression ratio and the Porosity has the change, the compression ratio of more than 50%, the compression ratiochange causes the Porosity change obviously, between them the relevance is stronger.3．In order to be advantageous for the comparison and the analysis, each cell substance of the compressed wood separately converts in the specimens which aren't compressed volume ratio,According to theory porosity computation, The cell substance of E.grandis×E.urophylla and Populus nigra L wood from the specimens which aren't compressed to the specimens which compression ratio 30%, separately dropped 0．8% and 0．5%, The cell substance of Cunninghamia lanceolata wood from the specimens which aren't compressed to the the specimens which compression ratio 40% does not change; The cell substance of E.grandis×E.urophylla and Populus nigra L wood from the compression ratio 30% to 60%, separately dropped 1．89% and 2．93%, The cell substance of Cunninghamia lanceolata wood from the compression ratio 40% to 60%, dropped 3．69%. Calculated by measuring porosity, The cell substance of E.grandis×E.urophylla and Populus nigra Lwood from the specimens which aren't compressed to the specimens which compression ratio 30%, separately dropped0．59%. 0．6%, the cell substance of Cunninghamia lanceolata wood from the specimens which aren't compressed to the specimens which compression ratio 40% dropped 0．55%; The cell substance of E.grandis×E.urophylla and Populus nigra L wood from the compression ratio 30% to 60%. separately dropped 8．85%,7．32%, The cell substance of Cunninghamia lanceolata wood from t the compression ratio 40% to 60%, dropped 7．76%.We can know from the cell wall substance analysis, Compression Inferiority fast-growing wood, thin-walled cells, vessel element, wood fiber and tracheid cells be squeezed, so the cell porosity has become smaller. E.grandis×E.urophylla and Populus nigra L wood cell wall began compacting when compression ratio greater than 30%, Chinese fir cell wall began compacting when compression ratio greater than 40%; With scanning microscope observation processing wood microscopicstructure,no damage to the cell wall, still maintain their integrity. Compression process, the pit cavity smaller, or even close cooperation, the pit membrane may rupture.4．Using between the multiple regression analysis establishment theory Porosity, the determination Porosity and the compression ratio mathematical model, the lumber theory Porosity and the compression ratio and the measuring Porosity may indicate by the below equation that:Z = ax + by + c:In forrmula :Z--theory Porosity %x--measuring porosity %y--Compression ratio %The regression equation fits superior above 96 %.5．The oven-dry density and the compression ratio and the measuring porosity may indicate by the below equation that:ρ₀ = ax + by+ c:In forrmula :ρ₀--oven-dry density g/cm³x--measuring porosity %y--Compression ratio %Regarding the E.grandis×E.urophylla and Populus nigra L a<0; b<0; c>0．Regarding the Cunninghamia lanceolata a>0; b>0; c>0;According to the oven-dry density, we can Directly introduce the relations of the compression ratio and the measuring porosity through this equation, provides the theory basis for the inferiority planted forest lumber compression and performance improvement.