Study On Cell Paths Opening Of Larch And Application With Technology Of Steam Explosion

This paper researches the cell paths of larch through the steam explosion treatment, showsthat it could open the aspirated pits of larch cell wall and improve the permeability of larch woodeffectively, research the effect on the structure of bordered pits and cross field pits, permeability,chemical composition, mechanical strength and fire retardant impregnation treatment of larchafter steam explosion treated.(1) According to the effect on the structure variation of bordered pits and cross field pitsthrough SEM before and after steam explosion treated, summarizes three models that the way ofwood cell channel opening after steam explosion treated. The first is micro fiber of pitsmembrane cracked and part aspirated pits become non-aspirated pits. The second is pits plugfractured so that aspirated pits become non-aspirated pits. The last is pits plug is broken bysteam and part pits plug fall off from pits membrane. For example some micro fibril of pitsmembrane have cracked and the number of micro fibril have increased after0.3MPa/10timessteam explosion treated; Larch wood cell wall become wrinkled, pits plug and micro fibril havedifferent damage after0.3MPa/15times and0.4MPa/10times steam explosion treated; The crossfield pits have cracked the damage degree of pits plug and micro fibril is max after0.4MPa/10times steam explosion treated.(2) The permeability of larch improved effectively after steam explosion treated andimproved by0.96-1.85times after different steam explosion treated compared with untreatedlarch. ANOVA shows that the difference of permeability between steam explosion treated anduntreated larch are very notable (α=0.01), and the difference of permeability after different steamexplosion pressure treated are very notable when the explosion time are fixed (α=0.01).(3) The chemical composition of larch changed after steam explosion treated. The averageSynthesis cellulose content of larch is changed from63.73%to54.15%; the average lignincontent of larch is changed from25.15%to28.47%, the average Pentosan content of larch ischanged from14.86%-3.83%, the average benzyl-alcohol extract content of larch is changedfrom2.83%to0.78%. ANOVA show that the difference of Pentosan content and benzyl-alcoholextract content between steam explosion treated and untreated larch are very notable (α=0.01).(4) Steam explosion treatment could influence the mechanical strength of larch. The MOEof larch is reduced3.82%-25.27%,the MOR is reduced15.73%-39.4%and the compressionstrength parallel to grain is reduced1.35%-22.03%after steam explosion treated. Although all themechanical strength of larch is decline, but ANOVA show that the difference between somesteam explosion treated and untreated larch are very notable (α=0.05). (5)The average fire retardant ratio, longitudinal, radial and the tangential impregnated depthare after steam explosion treated are higher than the untreated larch, and the average radialimpregnated depth is deeper than the average tangential impregnated depth. This part intends totest the effect on the practice of steam explosion treatment through fire retardant impregnation.(6) Summarize kinds of character of larch after steam explosion treated,0.3MPa/10times isthe best one among five steam explosion treatment.