Effects of alkali treatment on modification of the Pinus fibers

ABSTRACT The aim of this study was to evaluate the effect of the alkalization with different concentrations and time combination in the modification of lignin, hemicellulose and cellulose in pine fibers and determine the best combination aiming the incorporation in plant-based composites. The alkalization process was conducted with 5 concentrations (5, 10, 15, 20, and 30%) and 2 exposure times (2 and 24 hours). Chemical analysis was performed, and cellulose crystallinity, thermal stability, and surface modification were analyzed for the treated fibers. The results showed that there was a reduction in crystallinity with cellulose I – II transformation. Thereafter, the thermal stability and surface characteristics were increased with the increase of the NaOH concentration. Although all treatments altered the fiber properties, the condition that resulted in technical gain was the condition with 5% concentration and 2 hours of alkalization. Thus, we can conclude that this condition changes the macromolecular structure of the wood fibers, change the surface and the treat fiber could be used as filler to plant-base composite.摘要 本研究旨在评估不同浓度与时长组合的碱处理（alkalization）对松木纤维中木质素（lignin）、半纤维素（hemicellulose）及纤维素（cellulose）改性的影响，并筛选出最适处理条件，以应用于植物基复合材料（plant-based composites）的制备。本研究采用5种浓度（5%、10%、15%、20%及30%）与2种处理时长（2小时及24小时）开展碱处理实验。对经处理的纤维进行化学组分分析，并检测其纤维素结晶度（cellulose crystallinity）、热稳定性（thermal stability）及表面改性情况。结果表明，伴随纤维素I型向II型的转变，纤维的结晶度有所降低。此外，随着氢氧化钠（NaOH）浓度的升高，纤维的热稳定性与表面特性均得到提升。尽管所有处理条件均对纤维性能产生了改变，但可实现最优工艺效益的处理条件为5%浓度、2小时碱处理。综上，本研究得出结论：该处理条件可改变松木纤维的大分子结构（macromolecular structure）与表面特性，经处理后的纤维可作为填料（filler）应用于植物基复合材料中。