Study On The Effects Of Wettability And Micromechanics Of Fast-growing Poplar Unit Treated By Temperature Humidity Treatments

This paper studied on Poplar in order to research the specimen which were treated by Temperature Humidity treatments such as Hydrothermal treatmengts,Hydrothermal compaction treatments and High temperature treatments,then find out the variational rules of wettability and micromechanics by Modern analytical instruments such as Fourier Transform infrared spectroscopy(FTIR),Differential Scanning Calorimetry(DSC),Scanning Electron Microscope(SEM),Scanning Probe Microscope(SPM)Nanoindenter and High Performance Liquid Chromatography(HPLC)etc.The experimental results showed that using Temperature Humidity treatments processing can change the wettability and micromechanics of the Poplar unit,and the improvement is usefull to the bonding strength and mechanical strength.This application will have important significance if it is used in fast-growing wood processing field,especially in performance improvement of Wood-baset panel such as Plywood,Partical board.The main results of this paper were as follows:1.In Hydrothermal treatments with Poplar,with the increase of treatment time(the processing temperature was 100? and the processing time was respectively 2h,6h,10 h,14h),the surface wettability of Poplar increased.This change can be controlled through the processing time.Test results showed that the process of Hydrothermal treatment in the test range,the chemical structure of Poplar changed little.Some part of Hemicellulose degradation occurred,while physical aspects of the shape change of Cellulose and Ligin mainly occurred.Hydroxyl,carboxy and esters on the surface of the specimen had a tendency to reduce after Hydrothermal treatments modification and these changes are usefull to the surface wettability.2.In Hydrothermal treatments with Poplar,the specimens which were modified compared to which were not modified(the processing temperature was 100? and the processing time was 20h),the properties of micromechanics had a tendency to reduce because of Hydrothermal treatmengts.This processing played a softening effect.When the Hydrothermal treatments combined with densification process,whit the increa of Poplar compression ratio(the compression ratio was respectively 0,20%,33%),the properties of micromechanics had a tendency to increase.This change can be controlled through the compression ratio.Test results showed that in the Hydrothermal treatments combined with densification process,the chemical structure of Poplar changed little and some part of Hemicellulose degradation occurred while the shape change of Cellulose and Ligin mainly occurred.It belonged to physical change.Hydroxyl,carboxy and esters on the surface of the specimen had a tendency to reduce after modification.Physical aspects of the shape change of Cellulose and Ligin had an impact on the properties of micromechanics.3.In High temperature treatments with Poplar,under the condition of constant temperature(the processing temperature was respectively 160 ?,190 ? and 210?),with the increase of treatment time(the processing time was respectively 1h,2h,3h),the surface wettability of Poplar reduced.At the same time,the wettability cruve was not cross under the different processing temperature,and it appeared three regional distribution conditions which didn't overlap.With the increase of treatment temperature,the surface wettabilite of Poplar reduced.Test results showed that the changes of chenmical functional groups of specimen were significant in the process of High temperature treatments modification.Cellulose,Hemicellulose and Ligin degradation occurred which led to reduce the surface hydroxyl – OH and they were negative to the surface wettability of specimen.4.In High temperature treatments with Poplar,the specimens which were modified compared to which were not modified(the processing time was 3h and the processing temperature was respectively 160?,190? and 210?),the properties of micromechanics increased obviously when the treatment time was 160?,then the properties of Microelastic modulus and Microhardness reduced when the processing temperature increased.This change can be controlled through the processing temperature.Test results showed that the changes of chenmical functional groups of specimen were significant in the process of High temperature treatments modification.Cellulose,Hemicellulose Ligin and polysaccharide degradation occurred,and these changes were negative to the properties of micromechanics.5.The analysis of the components of the Poplar: The Poplar treated by Hydrothermal treatments showed that the chemical properties of the Poplar changed very little.The proportion of Cellulose and Ligin increased,the proportion of Semicellulose decreased obviously,and the proportion of other materials decreased obviously when the Poplar was in Hydrothermal treatments and with the increase of processing time,this trend was more obvious while the proportion of Ligin changed little.In the same way,The Poplar treated by high temperature showed that the chemical properties of the Poplar changed very much.The proportion of Cellulose decreased obviously,the proportion of Semicellulose decreased obviously,the proportion of Ligin decreased obviously,and the other materials increased obviously when the Poplar was in high temperature treatments and with the increase of processing temperature,this trend was more obvious.The proportion change of different materials had an relatively impact on the properties of wettability and micromechanics.