Study On The Distribution Of Wood Extractives

As an important component of wood,extractives have a great influence on the color,odor,physical and chemical properties of wood,which further affect the processing and utilization of wood.Based on the analysis of the chemical composition and the content of the wood extractives,the distribution of the extractives in the wood stem and cells was studied in this paper;According to the characteristics of the part distribution of the extract,the data fitting analysis of the pattern formation was carried out;At the same time,the effects of different surface treatments on extraction were studied.The results showed that there were great differences in the content and composition of wood extractives from different species,and even the same tree species had different extracts.Less content of extractives were existed in Pterocarpus macarocarpus Kurz.and Pterocarpus pedatus Pierre.,the content were from 18 percent to 21 percent;The greater density of Pterocarpus tinctorius specie was more similar to Pterocarpus santalinus L.F.because of Caryophyllene oxide and à-Bisabolol,which were appeared in both species;while the medium density of Pterocarpus tinctorius is more similar to Pterocarpus pedatus Pierre.because of common composition—3H-2-Benzopyran-3-one,1,4-dihydro-,à-Lindane and 3,6,9,12-Tetraoxahexadecan-1-ol.The extracts were distributed in the cells of the vessels,xylem rays and axial parenchyma of wood,and the surface of the cells has great differences between original and extracted samples,there were almost no extracts in cells atter extraction;The content of extractives from heartwood to sapwood in radial direction is decrease in the trunk,sapwood contains almost no extract,was 9.5 percent,while the external parts of the heartwood extractives content 27.9 percent more than the inner-layer 25.9 percent;in the longitudinal direction,descending from 32.04 percent at the breast height to 27.18 percent at the height of 5.3 meters.The black pattern on the surface of wood is due to the gathered aromatic extract,this pattern is not necessarily linked with the wood ring,but the trend in three sections issimilar to annual ring.In the tangential surface,the curve is formed by a series of para-bola,and with the decrease of angle between the surface and the bottom,the pattern is gradually changed from the parabola to the ellipse,eventually to a circular shape.Hydrothermal and sun-exposed treatment accelerated the process of transfer and oxidetion of extraction,deepen the color of wood.The more content of extractives,the greater change were existed with L*,C* and E* of the wood surface.KMnO4 made the color of wood surface become shallow,due to the reaction with lignin,therefore,the pattern of the extract was highlighted,especially when the concentration is 0.3 percent,with the faster rate of E* than else from 4.32 to 6.77.The study on the distribution of wood extractives provides a scientific basis for the improvement of properties,processing,utilization,and the identification of wood.