无胶竹碎料板喷蒸热压成型机理

The steam injection pressing molding mechanism of bindless bamboo particleboard

以竹碎料为原料,通过喷蒸热压工艺制备无胶竹碎料板。采用傅里叶红外光谱分析(FT-IR)、固体核磁共振波谱分析(CP/MAS13C NMR)、高效液相色谱分析(HPLC)以及比表面积分析(BET)等分析手段分析了无胶竹碎料板成型机理。结果表明,喷蒸热压过程的水、热协同作用使纤维素分子的活性羟基数量增加,活性羟基间可以形成氢键(O—H…H),在竹碎料间可以形成范德华力;喷蒸热压过程的水、热协同作用使竹碎料中的部分半纤维素产生水解,水解产物可以进行缩聚反应,生成类似于胶粘剂的缩聚呋喃树脂,也可以直接与具有酚羟基结构的木素发生缩聚反应,形成类似于酚醛树脂胶粘剂的缩合物。另外,竹碎料中的木质素受水热作用被充分流展并部分均匀分布在碎料颗粒间,一定程度上也改善了无胶板物理力学性能。

Bindless bamboo particleboard which takes bamboo particle as its raw material was prepared by steam injection pressing in this paper. Fourier transform infrared spectroscopy （FT IR）, solid-state nuclear magnetic resonance spectral analysis（CP/MAS ^13C NMR）, high performance liquid chromatography analysis （HPLC） and specific surface area （BET） were used to analyze the molding mechanism of bindless bamboo particboard. The results showed that the number of active hydroxyl in cellulose molecule was increased by the synergistic effect of the water and heat, active hydroxyl groups could form hydrogen bonds（O--H…H）, van der Waals forces was formed between each of the two bamboo particles in the process of steam injection pressing; part of hemicellulose in bamboo particle was hydrolyzed by the synergistic effect of the water and heat, the hydrolysate could be subjected to polycondensation reaction to generate polycondensation furan resin which was similar to adhesives, the hydrolysate also could be subjected to polycondensation reaction with the lignin having a phenolic hydroxyl structure to generate a kind of condensation compound which was similar to phenolic resin adhesive. In addition, the lignin in bamboo particle was fully expanded and part of lignin was evenly distributed between each of the two bamboo particles by the synergistic effect of the water and heat, which could improve the physical and mechanical properties of bindless particleboard to some extent.