糠醇浸渍对杨木压缩材物理力学性能的影响

压缩密实化是提升低质木材品质的有效手段,但遇水回弹是其主要技术难题,本研究旨在探讨糠醇树脂浸渍实现压缩木定型与改性同步的技术可行性。以西南乡土树种乡城杨木材为对象,研究了糠醇浸渍处理对其压缩材吸水性、尺寸稳定性、颜色和力学性质的影响,并以后期热处理的影响作为对照进行比较。结果表明:糠醇浸渍增重44.8%,能降低压缩木吸水率63%,提升其尺寸稳定性,吸水厚度回弹率只有4.38%～5.97%; 相比于未压缩杨木,糠醇浸渍压缩材的抗弯强度和表面硬度显著提高,增幅分别为89.1%和131.1%,但抗弯弹性模量只增加16.1%; 糠醇浸渍的压缩材具有酷似热带硬阔叶材的深色,明度和黄蓝度降幅大; 相比于后期热处理,糠醇浸渍对压缩材的定型效果略佳,且力学性质明显较优。因此,糠醇树脂浸渍技术不仅能良好固定压缩木变形,还可显著增强低质木材的力学性质,同时具有环境友好性。
Densification is a well-known method for improving the mechanical properties of low-grade wood. However, densified wood back to its original dimension in contact with water is its main technical problem. A combined fixation and modification procedure was developed in this study to solve this problem. Native low-grade poplar wood(Populus xiangchengensis)planted in southwestern China was selected for the study. Wood samples impregnated with furfuryl alcohol(FA)were densified with a compression set of approximately 30% and then subjected to cyclic water soak tests. Water uptake and spring-back data were recorded to evaluate the densification quality, and the results were compared with those of the densified wood with post thermal treatment. Color and mechanical properties of the densified poplar wood were also tested. Furthermore, the contribution of FA impregnation to set fixation of the densified wood was discussed. The results showed that a 44.8% weight percentage gain of the FA impregnation decreased 63% of the water uptake and lowered the thickness swelling to 4.38%-5.97%. The impregnation also improved the mechanical performance of the wood. The modulus of rupture, modulus of elasticity and hardness of the fufurylated wood increased by 89.1%, 16.1% and 131.1%, respectively. The furfurylated poplar wood exhibited dark appearance similar to tropical species with lower lightness index and lower yellow-blue index. Compared to wood with post thermal treatment, the furfurylated wood showed better set fixation and much higher mechanical strengths. It is therefore concluded that FA impregnation is a competitive method for fixing the compression set of the densified wood as it can also improve mechanical properties of the wood and is environmentally friendly