Preparation And Characterization Of Wood Modified By Metal Complexes

In order to improve the electrical conductivity of natural wood,the precursor solution was introduced into the wood by vacuum impregnation and drip injection.In the experiment,CuSO4 as metal salt,EDTA·2Na and KNaC4H4O6 as double complexing agents,NaH2PO2 as reducing agent,NiSO4 as catalyst and NaOH as pH regulator.The wood modified by metal complexes was measured.The structure and morphology of wood modified by metal complexes were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM)and photoelectron spectroscopy(EDX).The results showed that the structure and morphology of wood modified by metal complexes were as follows:1.In the experiment of preparing wood modified by vacuum impregnation,the wood weight gain rate increases with the increasing of the number of impregnation cycles,the volume resistivity decreases with the increasing of the wood weight gain rate,and the electrical conductivity increases gradually and then tends to be flat.When the number of impregnation cycles is 5,the wood weight gain rate reaches 81.6%,the volume resistivity is 2.449×103?·cm,and the electrical conductivity is the best.With the increase of vacuum impregnation temperature,the volume resistivity of wood modified decreases gradually,and the conductivity increases.When the vacuum impregnation temperature is 60?,the volume resistivity of wood modified reaches 2.309×103?·cm,and the conductivity is the best.When vacuum impregnation temperature is higher than 60?,the volume resistivity increases and conductivity decreases with the increase of impregnation temperature.With the increasing of copper sulfate concentration,the volume resistivity of wood modified decreases and the conductivity increases.When the concentration of copper sulfate is 50g/L,the volume resistivity of wood modified reaches 2.229×103?·cm,and the conductivity is the best.Then,with the increasing of copper sulfate concentration,the volume resistivity tends to be flat.When the vacuum impregnation temperature is 60?,the number of impregnation cycles is 5 times and the concentration of copper sulfate is 50 g/L,the volume resistivity of wood modified can reach 3.023×103?·cm,and the conductivity is the best.2.In the preparation of wood modified by drip injection method of living tree transpiration,the volume resistivity of wood modified decreases firstly,then increases,and the electrical conductivity first increases and then decreases with the increasing of cutting height of living tree segments.The volume resistivity of the second section is 4.33×106?·cm,and the conductivity is the best.The volume resistivity of wood modified decreases with the increase of copper sulfate concentration.When the concentration of copper sulfate is 50g/L and in the second section of the sample intercepted,the volume resistivity of wood modified reaches the lowest value of 4.33×106?·cm,and the conductivity of wood modified is the best in standing wood samples.3.Wood modified prepared by vacuum impregnation and drip injection were characterized by SEM,EDX,XRD and FTIR.The results showed that the metal complexes reduced to copper by catalysis in wood,and the molar mass fraction of basic elements C and O decreased that were replaced by copper and nickel.Some metal particles formed micro-clusters,and some metal particles formed chemical bonds with functional groups such as-OH,-C=O,-C-O,etc.The conductive mechanism of wood modified prepared by vacuum impregnation method is that metal particles form a dense metal layer inside the wood,and metal particles overlap with each other to form a continuous network structure,which combines the three conductive mechanisms of polymer conductive composites.It can be seen from the analysis that it is mainly explained by the conductive path theory,but there are also the field emission theory and tunnel effect theory.The conductive mechanism of wood modified prepared by drip injection method with transpiration of living standing trees is explained mainly by tunnel effect theory and field emission theory due to the low content of metal particles.