速生杨树木材表面的动态润湿性能和自由能研究

润湿性是木质材料的一个重要界面特性,它可以表征胶粘剂与木质材料接触状态,木材的表面润湿性能对木质复合材料的胶合强度有较大的影响。根据木质材料的结构与性能特点,笔者建立了描述其表面动态润湿性能的数学模型,在模型中提出了用系数K来评价胶的润湿性能；并运用该模型研究了脲醛树脂（UF）和酚醛树脂（PF）两种胶粘剂对杨木表面的动态润湿性能的影响,以及脲醛树脂胶对同一年轮内的早材和晚材的动态润湿性能，同时还研究了杨木表面自由能与其表面吸水量之间的关系。结果表明:与PF相比,UF在杨木表面的润湿性能较好，UF对早材的润湿性能比对晚材好；在相同时间内,杨木单位表面积吸水量越多,其表面自由能越大。

Study on the surface dynamic wettability and free energy of poplar

Wettability is an important interface characteristic of wood material. It' s used to describe what happened when an adhesive contacted with a wood surface. The surface wettability significantly the bonding strength of wood composites.In this study a wetting model was developed to describe the dynamic wettability on the surface of wood material according to its structure and properties, parameter K was used to evaluate the wettabitity during the adhesive wetting process. By applying the wetting model, The study showed that urea formaldehyde resin(UF) and phenol formaldehyde resin (PF)had the dynamic wettability on the surface of poplar. The UF resin has the dynamic wettability on the surface of its earlywood and latewood in same annual ring. Moreover, the relationship between the surface free energy and absorbed water of poplar was investigated as well. The result showed that UF resin exhibited a better wettability on poplar surface than PF resin. UF resin exhibited a better wettability on earlywood surface than on latewood surface. The more the poplar of per unit area absorbed liquid, the more its surface free energy had in the same time.