Transition characteristics of Brazilian vegetable fibers investigated by heating microscopy

ABSTRACT

Structural studies of three vegetable fibers plus eucalypt wood through heating microscopy, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and thermal analysis through Thermal Gravimetric Analysis/Differential Thermal Analysis are presented in this work. Morphological and dimensional changes obtained from heating microscopy were observed, showing shrinkage occurrences of vegetable fibers related to their diameter and length, respectively. The thickness decreased by 50% when heated at 450–500°C, this process starting at 300–400°C with an initial percentage length of ≈ 90%, that corresponds to a fast weight loss. These results were compared with simultaneous thermal analysis under the same conditions. Thus, for the first time, it was possible to quantify vegetable fiber dimensional changes and surface aspects under heating that cannot be seen by traditional thermal analysis. We also performed crystallinity calculations from XRD data, observing that cellulose/hemicellulose contents had major contribution in all samples.

摘要

本文通过热显微镜、FTIR、XRD和TGA/DTA热分析对三种植物纤维加桉木的结构进行了研究。观察到加热显微镜下的形态和尺寸变化，表明植物纤维的收缩率与直径和长度有关。在450～500℃加热时，厚度降低了50%，该过程起始于300～400℃，初始百分比为≈90%，相当于快速减肥。在相同条件下，将这些结果与同时热分析进行了比较。因此，第一次有可能量化蔬菜纤维的尺寸变化和表面方面的加热，不能看到传统的热分析。我们还进行了X-射线衍射数据的结晶度计算，观察到纤维素/半纤维素含量在所有样品中都有重要贡献。

KEYWORDS:

• Vegetable fiber
• coconut
• sugarcane bagasse
• sisal
• heating microscopy
• crystallinity

关键词:

• 植物纤维
• 椰子
• 甘蔗甘蔗渣
• 剑麻
• 加热显微镜
• 结晶度。

Additional information

Funding

The authors thank the Brazilian CNPq agency for their financial support, in particular grant numbers 304705/2015-2 and 404004/2016-4.