空气介质中热处理杉木压缩木材的蠕变

该研究采用空气介质中热处理,对径向压缩的杉木试材进行不同温度、不同时间的热处理,然后测定试材在绝干状态或吸湿解吸过程中的蠕变行为.结论为:①热处理杉木压缩木材在常温绝干状态下瞬时柔量和蠕变柔量(8h内)较小,在常温吸湿解吸过程中瞬时柔量和蠕变柔量(8h内吸湿结束时或20h内解吸结束时)较大,吸湿木材的瞬时柔量和8h内吸湿结束时的蠕变柔量分别可达绝干木材瞬时柔量和8h内蠕变柔量的1.5倍、3～5倍.②吸湿解吸过程中,热处理杉木压缩木材的蠕变行为不同于典型的木材机械吸湿蠕变,蠕变柔量没有表现出较大程度的增加.③热处理对杉木压缩木材的蠕变行为有很大的影响.热处理温度越高(乇鹪?00,220℃),时间越长,相应的试材在绝干状态或吸湿解吸过程中的瞬时柔量越大,某一时刻的蠕变柔量越大.杉木压缩木材在热处理过程中,木材细胞壁主成分发生降解反应是各柔量增大的主要原因.④就热处理杉木压缩木材在绝干状态或吸湿解吸过程中的瞬时柔量、蠕变柔量与相应热处理条件下回复率(RS)的关系而言,柔量越大,RS越小.热处理温度的高低,如200,220或140℃,对柔量与RS之间的关系有影响.烫

Creep of compressed wood of Chinese fir heat treated in air

In this study water saturated and boiled samples of Chinese fir ( Cunninghamia lanceolata ) are hot pressed, then heat treated in a common oven, with various treatment temperatures and time. Then their creep behaviors in dry conditions or during adsorption and desorption processes at room temperature are measured, respectively. The results are: ①The heat treated compressed specimens of Chinese fir have lower instantaneous compliances and creep compliances under the creep measurment conditions of dry specimens, while they have higher instantaneous compliances and creep compliances during adsorption and desorption. ②Their creep behaviors during adsorption and desorption do not present the typical characteristics of mechano|sorptive creep. ③The conditions of heat treatment have great effects on the creep behaviors of compressed wood. The higher the temperature, the longer the time, then the higher the instantaneous compliances or the creep compliances under certain conditions. The decomposition of the main components of wood cell wall leads to the increase of the compliances. ④There exist certain relationships between instantaneous compliances or creep compliances and the set recovery of heat treated compressed wood of Chinese fir. The higher the compliances, the higher the recovery. The temperature of heat treatment has obvious influence on the relationships between the compliances and the set recovery.