Research On The Effects Of Physical And Chemical Properties Of Wood After Fumigation Treatment

The entry-exit wood packaging materials often carry a large number of insect pests,so quarantine treatment should be carried out for preventing the spread of various biological pest with wood.The research objective is to study the effects of fumigation treatment on physical and chemical properties of poplar(Populus lasiocarpa Oliv)and larch(Larix gmelinii).Three kinds of fumigants(carbonyl sulfide,COS;methyl bromide,MB;sulfuryl fluoride,SF)were used to process poplar and larch in three different concentrations,and the color difference detection,scanning electron microscope(SEM),energy dispersive spectrometer(EDS)and Fourier transform infrared(FTIR)spectroscopy were used to analyze the fumigation treatment influence on physical and chemical properties of wood samples.The results are as follows:1)Poplar and larch wood color were obviously altered after fumigation treatment,and COS fumigation treatment had minimal impact on brightness(L*),red and green chromaticity index(a*).However,after COS fumigation treatment,the compression strength parallel to the grain,the bending strength and the elastic modulus of poplar and larch samples decreased significantly,and compressive strength had the greatest reduction at condition of concentration at 124.2 g/m3,paplar samples decreased by 11.51%,and the bending strength and the elastic modulus of samples fell by 8.62%and 8.26%,respectively;Also,compressive strength of larch samples decreased by 13.09%,and the bending strength and the elastic modulus of larch samples fell by 9.38%and 8.66%,respectively.After MB fumigation and SF fumigation treatment,the compression strength parallel to the grain,the bending strength and the elastic modulus of poplar and larch samples hardly changed.After fumigation processing,the surface microstructure of samples was maintained,but the surface S and F element distribution slightly increased after COS/SF fumigation treatment.Gase released analysis of wood before and after fumigation processing showed that SO2 gas concentration increased significantly after COS fumigation treatment.In FTIR spectroscopy of P.lasiocarpa:the absorption peak at 1734 cm-1 enhanced obviously after MB or SF fumigation treatment,and that means C=O bonds increased obviously;After COS fumigation treatment,the absorption peak at 1045 cm.1,1598 cm-1 and 1510 cm-1 fell,and that means C-O bonds and C=O/C-C bonds even on the aromatic ring skeleton are decreased.In the infrared spectroscopy of larch wood,the C=O and C-H bonds increased obviously after MB and SF fumigation processing;After COS fumigation processing,the C=O stretching vibration of hemicellulose became weakened,but the C=O stretching vibration of aromatic ring skeleton became stronger,and the content of lignin increased.