组坯结构对竹材胶合界面破坏行为及细胞壁力学性能的影响  

Effects of the assembly structures on the failure behaviors and mechanical performance of bamboo-phenol-formaldehyde adhesive interphase

作　　者：曹倚中 吴妤婷 徐淑伟 徐楚航 金春德[1] 王思群[2] 吴强[1] CAO Yizhong;WU Yuting;XU Shuwei;XU Chuhang;JIN Chunde;WANG Siqun;WU Qiang(National Engineering and Technology Research Center of Wood-Based Resources Comprehensive Utilization,College of Chemistry and Materials Engineering,Zhejiang A&F University,Hangzhou 311300,China;Center for Renewable Carbon,University of Tennessee,Knoxville TN 37996,USA)

机构地区：[1]浙江农林大学化学与材料工程学院,国家木质资源综合利用工程技术研究中心,杭州311300 [2]田纳西大学可再生碳研究中心,美国诺克斯威尔37996

出　　处：《林业工程学报》2023年第3期39-45,共7页Journal of Forestry Engineering

基　　金：国家自然科学基金(31870548)。

摘　　要：竹质工程材料在轻质结构建筑及其关键承载构件中有巨大的应用潜力,然而竹材天然径向结构差异性会对其胶合质量造成显著影响。以4年生毛竹材和酚醛树脂(PF)胶黏剂为原料制备了双层竹片层积材,探讨组坯结构对双层竹片层积材的宏观胶合性能和胶合界面细胞壁力学性能的影响。研究结果表明,外表面-外表面(O/O型)组坯时竹片层积材的胶合剪切强度(干态胶合强度17.3 MPa,湿态胶合强度5.3 MPa)显著高于外表面-内表面(I/O型)和内表面-内表面(I/I型)组坯样品。这主要是由于O/O型竹材胶合界面内薄壁细胞壁的力学性能更加接近厚壁细胞壁,改善了界面内应力集中现象。PF胶黏剂在不同组坯结构竹材胶合界面内的差异性渗透行为是造成这一现象的主要原因:竹材薄壁细胞表面氧碳比较高(0.40)且毛细管作用较强,在I/O型和I/I型界面内PF胶黏剂的渗透行为主要表现为填充细胞腔;而在O/O型界面内PF胶黏剂能够有效浸润薄壁细胞壁,而非简单填充其细胞腔,因此O/O型竹片层积材具有更高的界面细胞壁力学强度和宏观胶合强度。Engineered bamboo products(EBPs),such as laminated bamboo veneer lumber and parallel bamboo strand lumber,have exceptional potential for applications in lightweight frame construction and load-bearing elements.Massive effort has been poured onto improving the mechanical performance of EBPs since the applications spread in recent decades.Fundamental insights into the adhesion performance of bamboo and adhesive are desired cause it effects the mechanical performance of EBPs significantly.The inherent variant in the radial structures of bamboo leads to significant effects on the adhesion performance of bamboo.Here,double-layered bamboo-adhesive bonds were prepared using the four-year-old Moso bamboo and phenol-formaldehyde(PF)adhesive.The effects of assembly structures on the mechanical performance of bamboo-PF bonds were investigated.The obtained results revealed that the shearing strength of outer layer-outer layer(O/O)bamboo-PF bonds was 17.3 MPa(dry)and 5.3 MPa(wet),which was higher than the ones of outer layer-inner layer(I/O)and inner layer-inner layer(I/I)bamboo-PF bonds.Nanoindentation demonstrated that the infiltration of PF adhesive elevates the mechanical performance of the parenchymal cell wall(reduced elastic modulus of 17.7 MPa and hardness of 0.61 GPa).Thus,the huge gap of mechanical properties between the parenchymal cell wall and the sclerenchymatous cell wall in bamboo was narrowed when assembled as O/O.It is beneficial for enhancing stress transfer when bamboo-PF bonds are subjected to load.The study also revealed that the differences in the wettability of PF adhesive on the parenchymal/sclerenchymatous cell walls lead to the different penetration behaviors of adhesive in bamboo-PF interphase.It results in the elevated filling of PF adhesive in the parenchymal cell walls in the O/O bamboo-PF interphase,which is the major reason underlying the enhanced mecha-nical performance of O/O bamboo-PF bonds.PF adhesive was forced to infiltrate the parenchymal cell wall in O/O bamboo-PF interphase,while it t

关 键 词：竹材 酚醛树脂胶黏剂 胶合强度 竹材胶合界面 纳米压痕 

分 类 号：S781.9[农业科学—木材科学与技术] TU531.3[农业科学—林学]