不同压缩率下杉木低分子质量酚醛树脂浸注研究

Impregnating low-molecular-weight phenol formaldehyde resin into Chinese fir wood under different compression ratios

[目的]在不同压缩率下对杉木的低分子质量酚醛树脂浸注进行较为系统的研究,以期为人工林杉木的树脂浸注处理提供理论依据和技术参考.[方法]采用万能力学试验机对杉木试样进行径向压缩,使其压缩率分别为10%,20%,30%和40%,通过差示量热扫描仪对不同压缩率下杉木的微孔隙变化进行分析;以水溶性低分子质量酚醛树脂为浸注液,对不同压缩率下杉木在不同浸注阶段(卸压过程、卸压后)和不同浸注时间下的树脂浸注量及相应的浸注贡献率按照杉木试材重量变化进行测算,探索杉木压缩率与增重率之间的关系;通过超景深三维显微镜观测和傅里叶红外光谱,对压缩浸注后树脂在杉木中的分布及官能团变化进行分析.[结果]1)压缩处理能有效增大杉木的微孔体积,尤其是1~20 nm和200~400 nm孔径的孔隙体积显著增加.2)杉木在压缩率为10%~40%时,随着压缩率的提高,酚醛树脂的最大浸注量从0.053 g/cm^(3)增加至0.265 g/cm^(3),卸压过程的浸注贡献率由16.85%增加至53.19%.在试验的所有压缩率下,酚醛树脂的浸注贡献率均在30 min内达到60%.3)杉木树脂压缩浸注的增重率与压缩率呈线性正相关关系,在压缩率不超过40%的情况下,压缩率每升高1%,杉木的增重率增加0.22%.4)酚醛树脂溶液浸注杉木时,其不但能浸注到杉木细胞腔内,也能浸注到细胞壁内,并且与细胞壁成分产生化学交联.[结论]压缩处理能很好地使低分子质量酚醛树脂浸注入木材中,有效提高树脂的浸注效率.在工业浸注处理时,为了提高树脂的浸注量和浸注效率,应尽量选取较高的木材压缩率,并注重卸压阶段的浸注效果.

【Objective】A systematic study has been carrid out on the low molecular weight phenol formaldehyde resin impregnation of Chinese fir under different compression ratios in order to provide the theoretical basis and technical para meters for phenol formaldehyde resin impregnation treatment of Chinese fir.【Method】A universal testing machine was used to radially compress Chinese fir sample to make the compression ratios of 10%,20%,30%and 40%,respectively.The micro pore volume changes at different compression ratios were measured by differential scanning calorie(DSC).Using water-soluble low-molecular-weight phenol formaldehyde resin as impregnation solution,the resin impregnation amount and the corresponding impregnation contribution of Chinese fir in the different impregnation stages during and after the release of compression and with different impregnation times were calculated by weight changes of specimens.The distribution of resin in Chinese fir was observed by Ultra-depth-of-field microscope and the functional group changes treated by resin were analyzed by Fourier infrared spectrum.The relationship between compression ratio and weight percent gain was also examined.【Result】(1)The compression significantly increased volume of micro pores of Chinese fir,especially for those with sizes of 1 nm to 20 nm and 200 nm to 400 nm.(2)With the increase of compression ratio from 10%to 40%,the total impregnation amount increased from 0.053 g/cm^(3) to 0.265 g/cm^(3),and contribution ratio during the release of compression increased from 16.85%to 53.19%.Impregnation contribution reached 60%within 30 min for all tested compression ratios.(3)A proportional linear relationship between compression ratio and weight percent gain was found.With every 1%increase of compression ratio,the weight percent gain increased by 0.22%when compression ratio was less than 40%.(4)The resin was found in both surface of lumen and inside the wall.It also showed a cross-link with cell wall of wood.【Conclusion】The impregnation by compression was very effective for impregnation of low-molecular-weight phenol formaldehyde resin into wood.For industry practice,high compression ratio was recommended for high impregnation ratios.