提高杨木线性振动摩擦焊接胶合性能的研究

研究了杨木线性振动摩擦焊接的干剪切强度、湿剪切强度和木破率。为提高杨木摩擦焊接的湿剪切强度与木破率,采用表面氧化、表面磺化以及表面涂覆的方式处理杨木板材,再经线性振动摩擦焊接进行黏合,使用万能力学试验机测得其剪切强度,对比表面处理前后剪切强度的变化,并利用傅里叶红外光谱分析了其表面处理前后基材和摩擦焊接层的化学基团变化情况,对胶合性能的变化做出解释。研究结果表明:杨木经过表面氧化磺化涂覆醋酸锌处理后,摩擦焊接层的干剪切强度为5.41 MPa,木破率为63%,与未处理的杨木相比,分别提高了48.22%和96.88%;湿剪切强度从0提高到1.34 MPa;摩擦焊接时厚度损失减少了46.4%。杨木分别经过表面氧化和表面磺化处理后,摩擦焊接层的干剪切强度仅为3.45和4.10 MPa,木破率为28%和42%,湿剪切强度为0.76和0.96 MPa。摩擦焊接层的红外光谱分析表明,经表面氧化磺化涂覆醋酸锌处理后,杨木中的纤维素和半纤维素分解,使木质素的相对含量有所增加,且活化了杨木中的—OH,与醋酸锌生成多醚,消耗了亲水性的—OH。

Enhancement of gluability of poplar with linear vibration friction welding

Friction welding technology was firstly applied to thermoplastic materials such as metals and plastics. Due to its environmental-friendly and efficient features, the friction welding technology has a huge potential to be used as a wood bonding technology. Lignin can be the main adhesive for wood friction welding, as oxidation reaction and sulfonation reaction can make changes for the structure of lignin. The dry shear strength, wet shear strength and wood failure of poplar with linear vibration friction welding were studied. In order to improve the wet shear strength and wood failure of poplar with linear vibration friction welding, the poplar surface was treated by the oxidation reaction, sulfonation reaction and surface coating. The poplar boards were bonded together through the linear vibration friction welding, then the shear strength was tested and the changes of shear strength before and after surface treatment were examined. The changes in the chemical groups of poplar and friction welded layers after surface treatment were observed by the Fourier transform infrared (FT-IR) spectrum, and the change in the gluability of wood friction welding was also explained. The results showed that after the surface treatment by oxidization and sulfonation along with zinc acetate coating, the dry shear strength of the friction welding layer was 5.41 MPa, and the wood failure was 63%. Compared with the untreated poplar, the dry shear strength and wood failure of treated poplar increased by 48.22% and 96.88%, respectively. The wet shear strength was increased to 1.34 MPa, and the thickness loss during the friction welding process was reduced by 46.4%. After the poplar was oxidized or sulfonated, the dry shear strength of the friction welding layer was 3.45 MPa or 4.10 MPa, respectively, the wood failure was 28% or 42%, respectively, and the wet shear strength was 0.76 MPa and 0.96 MPa, respectively. The results of FT-IR showed that, after the surface treatment by oxidation and sulfonation along with zinc acetate coating of poplar, the cellulose and hemicellulose were degraded, and the relative content of lignin was increased. The oxidation reaction and sulfonation reaction also activated the -OH in poplar, and produced polyether with zinc acetate, which consumed hydrophilic-OH.