| Eucalyptus camaldulensis possess the advantages such as hifat, cold resistance, fast-growing, disease resistance and so on. Widely used in wood-based panels, furniture flooring industry. But juvenile E. camaldulensis contain rich extractives. It leads to serious flaws in the product process. Since the complexity and varition of the chemical composition of the extractive during the process, it is hard to determine which compounds have affect the processing properties.To improve the performance of the wood processing control technology, the results of the reach show that:(1) When the pyrolysis temperature is 350℃It separates 224 peaks from the benzene/ethanol extractives of E. camaldulensis, from which identify 174 constituents by Py-GC-MS and occupy 99.94% of the whole area. It separates 224 peaks from the ether/acetone extractives of E. camaldulensis as,from which identify 127 constituents by Py-GC-MS.and occupy 80.16% of the whole area. When the pyrolysis temperature is 600℃. It separates 204 peaks from the benzene/ethanol extractives of E. camaldulensis, from which identify 144 constituents by Py-GC-MS and occupy 99.64% of the whole area. It separates 193 peaks from the ether/acetone extractives of E. camaldulensis as, from which identify 106 constituents by Py-GC-MS and occupy 80.61% of the whole area. When the pyrolysis temperature is 750℃. It separates 234 peaks from the benzene/ethanol extractives of E. camaldulensis, from which identify 184 constituents by Py-GC-MS and occupy 98.88% of the whole area. It separates 204 peaks from the ether/acetone extractives of E. camaldulensis as, from which identify 116 constituents by Py-GC-MS and occupy 80.67% of the whole area.(2) The optimum concentration of KOH, NaOH, LiOH was 17.5%,18.5%,15.0% at 25℃, successively. The optimum extraction time of the untreated samples was 20h,24h, 24h, respectively. And the optimum extraction time of the treated samples was 16h,16h, 12h, respectively.The kinetie of extractive dissolving indieates that extraetive removal during impregnation can be divided inio three phases:the rapid extractive removal phase,moderate removal phase and the stable phase.According the results obtained in this research,there is nearly no extractive dissolving at the stable phase and it also find that extractives dissolve rapidly under high temperatore,and needs less time to get to the stable phase. Removal of the extractive follows as a first order reaetion.As the result of this study, the reaction order is 1.02.The reaction rate constant is positively related to the temperature, the active energy of the reaction Ea=14549.86J/mol, and the factor of pre—index A=20.48min-1.(3) The results of the infrared spectrum,nuclear magnetic resonance(NMR) spectrum, electronic microscope photos shows that the influencing mechanism of E. camaldulensis extractives on the bond performance can be concluded as follows:①The hydrophily component of E. camaldulensis extractives can be move onto the surface of E. camaldulensis wood during the drying process. When the moisture escape from the surface the extractives retained in the product surface.It will pollute the Eucalyptus wood interface,prevent the spread of glue into the wood surface,resulting in poor adhesive curing.②The resin compounds of the extracts will block the channels and will hinder the occurrence of adhesive connection of the wood surface active groups and active groups.It will have a serious impact on the performance of wood glue.③The acidic compounds of the extractives will reduce the PH value of the interface to extend the glue curing time,and the PH value of the cement layer of adhesive can cause solidification of reduced precipitation,resultion in the wood-adhesive interface with an opportunity to pay decreased,reducing wood and glue between the cross-linking.In addition, alcohols, aldehydes, ketones extract easily oxidized, but also incerases the acidity of the wood. |
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