Effect of Sodium Hydroxide Treatment on Physico-chemical, Thermal, Tensile and Surface Morphological Properties of Pongamia Pinnata L. Bark Fiber

ABSTRACT

Surfaces of Pongamia pinnata L. fiber (PPF) were modified by the 5% (w/v) sodium hydroxide solution with the various immersing period as 15, 30, 45, 60 and 75 minutes. Chemical compositional analysis evidenced that 5% (w/v) sodium hydroxide solution with 60 minute immersing period is optimum treatment. Removal of lignin content from the optimally treated PPF was detected through the chemical analysis as well as Fourier Transform-Infrared spectroscopy. X-ray diffraction analysis outcomes established the enhancement in the crystallinity index (45.31% to 52.43%) and crystallite size (5.43 nm to 8.32 nm) of the optimally surface-modified PPF. Improvement in the maximum cellulose degradation temperature (332°C to 348°C) and kinetic activation energy of the optimally-surface modified fibers (68.642 KJ/mol to 72.563 KJ/mol) were acknowledged from differential thermogravimetric curve and broido plots. Scanning electron microscope and atomic force microscopy investigations visualized the improvement in surface roughness of the PPF after alkalization. All the above findings authorized the suitability of optimally surface modified PPF as reinforcement in lightweight polymer composite applications.

摘要

Pongamia pinnata L. 纤维 （PPF） 的表面由 5% （w/v） 氢氧化钠溶液进行改性，各种浸浸期为 15、30、45、60 和 75 分钟. 化学成分分析表明，5%（w/v）氢氧化钠溶液具有60分钟的浸泡期是最佳处理. 通过化学分析和傅立叶变换红外光谱法，从最佳处理的PPF中去除木质素含量. X射线衍射分析结果证实结晶度指数的增强（45.31%至52.43%）和最佳表面改性 PPF 的结晶尺寸（5.43 nm 到 8.32 nm）. 从差分热重力曲线和溴多图中确认最佳表面改性纤维（68.642 KJ/mol 至 72.563 KJ/mol）的最大纤维素降解温度（332°C 至 348°C）和动能活化能量的改善. 扫描电子显微镜和原子力显微镜研究可视化了碱化后PPF表面粗糙度的改善. 上述所有发现都认可了最佳表面改性PPF作为轻质聚合物复合材料应用的增强物的适用性.

KEYWORDS:

• Pongamia pinnata L. fiber (PPF)
• alkali treatment
• optimally surface-modified fibers
• chemical analysis and thermal stability

关键词:

• 纤维（PPF）
• 碱处理
• 最佳表面改性纤维
• 化学分析和热稳定性