摘要
木材细胞壁孔隙结构对热处理材导热性能和进一步改性有着重要的影响。氮气吸附法是表征木材细胞壁孔隙的重要手段,研究结果表明,在热处理温度≤170℃时,木材残余结合水和挥发分的失去,使得微纤丝间隙(微孔)变少和纹孔膜上孔隙(35 nm<中孔<40 nm)减少;随着热处理温度的升高,微孔变多,纹孔膜上部分原有较小中孔被扩展成较大中孔;但当温度达到230℃左右后,由于热解反应加剧,微纤丝微孔坍塌或被扩展为较小中孔,纹孔膜中孔继续被增大,中孔增多。因此,随着热处理温度的升高,木材微孔、中孔和总孔的孔容以及比表面积均基本呈现先降低后增加的变化趋势,这与热处理木材三个方向上导热系数的变化呈相反的趋势,证明细胞壁孔隙是决定热处理木材导热性能的重要因素,且细胞壁孔隙的增加不利于木材热的传导。
Pore structure of wood cell wall has an important effect on thermal conductivity and further modification of heat-treated wood.Nitrogen adsorption method is an important method to characterize the pores in wood cell wall.The results show that when the heat treatment temperature is less than 170℃,the loss of residual binding water and volatile matter led to a decrease of microfibril interval(micropores)and pit membrane pores(35 nm<mesopores<40 nm).With increasing temperature,more micropores formed,and the small mesopores were expanded into larger mesopores.However,when the temperature reached 230℃,because of the intensification of pyrolysis reaction,the micropores collapsed or expanded into the small mesopores,and the mesopore diameter continued to be enlarged.Therefore,as the heat treatment temperature increased,the pore volume and specific surface area of wood micropores,mesopores and total pores decreased firstly and then increased.The thermal conductivity of heat-treated wood in three directions showed an opposite variation trend,proving that the cell wall pore was one of the important factors to influence the thermal performance of heat-treated wood,and the increase of cell wall pores was not conducive to wood heat conduction.
作者
刘世培
刘文静
王斌
张明辉
LIU Shipei(Collage of Materials Science and Art Design,Inner Mongolia Agricultural University,Hohhot 010018)
出处
《林业科技》
2022年第4期29-33,共5页
Forestry Science & Technology
基金
国家自然科学基金项目(31960292)
内蒙古自治区自然科学基金(2021MS03046)。
关键词
热处理木材
细胞壁
空隙
导热系数
木材改性
Heat-treated wood
Cell wall
Porosity
Thermal conductivity
Wood modification
