Research On The TVOC And Odor Of Common Tree Species In South China Under Different Moisture Contents And Lacquer Decoration

As an important raw material,wood is widely used in energy production,furniture materials,papermaking and other fields.With the widespread use of wood materials,the impact of its odor on the indoor environment has attracted much attention.The main smell of wooden homes—on the one hand,comes from the extracts contained in the wood itself,on the other hand,it comes from the surface decoration coatings and additives used in the production process,so the odor components released by the wood itself and the odor of the painted board Research on changes is conducive to solving the problem of "odor" emitted when wood is used as an interior decoration material.In this study,ten commonly used tree species in the south(P.massoniana Lamb,Eucalyptus grandis xE.urophylla,C.mollissima B1,Osmanthus fragrans Lour,P.neurantha(Hemsl.)Gamble,C.camphora(L.)Presl,C.burmanii(Nees)B1,Choerospondias axillaris(Roxb.)Burtt et Hill,Broussonetia papyrifcra(L.)Vent,Melia azedarach L,T.sinensis(A.Juss.)Roem)were taken as examples.Smell technology(Gas chromatography-mass spectrometry/olfactometry,GC-MS/O)analyzes the TVOC and characteristic odor active compounds released from the heart and sapwood of ten species of wood under different moisture content,and explores ten species of species The laws and odor differences of TVOC released by wood under different moisture content;at the same time,these ten tree species after reaching the equilibrium moisture content are painted and veneer(PU paint veneer,UV paint veneer,water-based paint veneer),Investigate the difference in the odor of the board after painting and the effect of the painting on the smell of wood.The main conclusions are as follows:(1)With the decrease of water content,TVOC release rate of different tree species was different,and the best release period of TVOC was significantly different.For example,the best release period of TVOC from the heartwood and sapwood of P.neurantha(Hemsl.)Gamble was during the initial decline of moisture content;The best release period of TVOC in heartwood of P.massoniana Lamb.was from moisture content to fiber saturation point,while that in sapwood was from fiber saturation point to atmospheric equilibrium;The best release period of TVOC in heartwood of Choerospondias axillaris(Roxb.)Burtt et Hill was when the moisture content decreased from fiber saturation point to air saturation point,and it was the main release period of TVOC in sapwood before the moisture content decreased to fiber saturation point.(2)The influence of water content on the overall odor characteristics of different tree species is different,For example,with the decrease of water content,the overall odor composition of heartwood and sapwood of P.massoniana Lamb.was dominated by peppermint pungent flavor and fragrance.The overall odor characteristics of heartwood and sapwood of Osmanthus fragrans Lour.before the fiber saturation point were formed by the interaction of fruit flavor and other special flavors.When the moisture content decreased to the fiber saturation point,flower sweetness became the dominant odor component of the whole odor characteristics of Osmanthus fragrans Lour.;Moreover,due to the different release rates of odor characteristic compounds in the same solid wood at different moisture contents and the synergistic antagonism among odor characteristic compounds,the overall odor of the same solid wood at different moisture contents also has significant differences.For example,when the moisture content of heartwood of Broussonetia papyrifcra(L.)Vent.was 70%and 5%,the main odor was aromatic and sweet flower,while when the moisture content was 50%,30%and 10%,the main odor was fruit and special pungent;During the period from fiber saturation point to atmospheric equilibrium state,the overall odor characteristics of heartwood of Melia azedarach L.were mainly fruit aroma and aromatic aroma,when the moisture content decreased to 5%,the overall odor characteristics were dominated by flower aroma,sweet aroma and aromatic aroma.At the fiber saturation point of sapwood of Melia azedarach L.,fruit flavor was the main component,when the moisture content decreased to the atmospheric equilibrium state,the overall odor characteristics of sapwood of Melia azedarach L.were mainly fragrance.In addition,the overall odor characteristics of heartwood and sapwood of the same tree species were different,for example,the relative intensity of fruit aroma released from heartwood of C.mollissima Bl.was stronger than that from sapwood of C.mollissima B1..When the moisture content of heartwood of C.camphora(L.)Presl was 50%,camphor flavor and flower sweet flavor were the main odor characteristics,while when the moisture content of sapwood of C.camphora(L.)Presl was 50%,fruit flavor,camphor flavor and other special flavor were the main odor characteristics.(3)The influence of different lacquer surface on TVOC release of different tree species was different.For example,the three kinds of lacquer had a good inhibitory effect on the release of TVOC from P.massoniana Lanb.However,TVOC release from Aucalyptus grandis xE.urophylla and Melia azedarach L.increased after three kinds of coating.The release of TVOC from C.mollissima B1.treated with UV paint decreased,while the release of TVOC increased after PU paint and waterborne paint treatment.Moreover,the effects of different coatings on wood VOC were significantly different from that on the overall odor characteristics and odor intensity of wood.For example,the release of TVOC from C.mollissima B1.treated with water-based paint increased sharply,but the overall odor intensity of C.mollissima B1.treated with water-based paint decreased significantly;UV paint had the best inhibitory effect on TVOC of P.massoniana Lamb.,but the overall odor intensity of P.massoniana Lamb.was the weakest after finishing with water-based paint;The concentration of toluene in P.neurantha(Hemsl.)Gamble treated with UV paint increased sharply,but the overall odor intensity was the lowest among the three kinds of P.neurantha(Hemsl.)Gamble lacquered veneers.Therefore,lacquer coating has a good inhibitory effect on the tree species with high TVOC release,but for the tree species with low TVOC release,lacquer treatment will increase the release of TVOC and VOC.In addition,the change of VOC and overall odor should be considered comprehensively when the wood is painted,and the "odor" problem after finishing should be reduced while the TVOC release is reduced.