Study On Modifying Populus Wood By Silicates

Poplar is an important fast-growing wood in China.The effective use of fast-growing Poplar has been one of the important solutions to the gap of the consumption in our country.It is a hot topic that dealing with modifying fast-growing timber by the using of low-cost,simple process in the area of the wood modification.In this paper,sodium silicate(water glass) and aluminum sulfate as a modification reagents,fast-growing Populus ussuriensis wood was modified by three methods(treatment by water glass,marked as group A;treatment firstly by water glass then by aluminum sulfate solution,marked as group B;treatment firstly by aluminum sulfate solution,drying,and then treatment by water glass,marked as group C).The physical and mechanical properties,the combustion characteristics,the micro-structure of the modified poplar and its cellulose crystallinity were analyzed and discussed,and an optimal modification process was put forward.The color of the modified wood changes in varying degrees,however,group B and group C had a tiny degree of discoloration,and basically this does not affect the appearance of the wood.With the weight gain rate of poplar increased,the full-dry density and the hardness of poplar had a corresponding increase,and the impact strength decreased.Group C poplar showed a more obvious increase in the hardness,while the decrease of impact strength reduced to the minimum.TTI(Time to Ignition) of the modified wood specimens have been shorted,however, HRR(Heat Release Rate),THR(Total Heat Release),FPI(Fire Performance Index) and the other combustion parameters showed that the char yield was significantly higher than the untreated wood,and this indicated a substantial improvement in the fire-retardancy of the modified poplar wood.The smoke parameters of SR(Smoke Ratio),TSP(Total Smoke Product) and mean-SEA(Specific Extinction Area) of the modified poplar showed a better performance of smoke suppression.The analysis results of the combustion exhaust of the wood showed that the CO concentration of group A and B was lower than the untreated wood,while the value of group C was slightly higher than the untreated.However only minor changes were observed and this indicated that the silicate treatment of wood basically does not influence its smoke toxicity.After poplar wood was modified by group A,its cellulose crystallization zone was suffered destruction,and the modification of group B and group C had an effect only in the amorphous area of cellulose to a certain extent.SEM observation showed that the filler in the crystalline catheter of the modified wood group B and group C was fixed more reasonably than the case in group A.To use sodium silicate as the main reagents for the modification of poplar wood,the reagents had a great influence on its properties.For the reagents and the method in this article,group C is the best,based on not changing as much as possible in the timber structure and supplying with better mechanical and fire-retardant and smoke suppression performance.