Biological Natural Retting for Determining the Hierarchical Structuration of Banana Fibers

Abstract

Extraction processes of natural fibers can be performed by different procedures that include mechanical, chemical and biological methods. Each method presents different advantages or drawbacks according to the amount of fiber produced or the quality and properties of fiber bundles obtained. In this study, biological natural retting was satisfactorily used for obtaining banana fibers from plant bunches. However, the most important contribution of this work refers to the description of the hierarchical microstructural ordering present in banana fiber bundles in both bundle surface and inner region. The chemical composition of banana fiber bundles has been evaluated by FTIR spectroscopy. Through exposure time, the fiber bundle configuration presents small variations in composition. The main changes are related to hemicellulose and pectins as they conform the outer walls of the bundle. Hierarchical helicoidal ordering in the bundle surface as well as orientation on the longitudinal axis of the bundle were observed by optical microscopy (OM) and scanning electron microscopy (SEM) for 3-4 microm surface fibers and 10-15 microm inner elementary fibers, respectively. With increasing exposure time, fiber bundle walls lose integrity, as reflected in their mechanical behavior.

Microstructural, Thermal, and Tensile Characterization of Banana Pseudo-stem Fibers Obtained with Mechanical, Chemical, and Enzyme Extraction

“…The tensile properties of BPSFs decreased as a consequence of enzymatic extraction, relative to the important changes registered by the fibers. The enzyme attacks the fibers, resulting in the disappearance of the fiber cell walls and loss of their compactness, which leads to a decrease in the tensile properties of fibers (Ganan et al 2004;Dai et al 2011). Moreover, the corresponding elongation of BPSFs also displayed the same trend.…”

“…Various methods, including chemical, mechanical, enzymatic, and combined treatments, have been reported to extract fibers from BPS. Each method presents different advantages or drawbacks according to the amount of fiber produced or the quality and properties of fiber obtained (Ganan et al 2004). Chemical treatment is usually conducted by immersing samples into alkaline solution, based on the mechanism that cellulose and non-cellulosic substances have different stabilities in the solution.…”

“…Mechanical separation of fibers from BPS is implemented by scraping, hacking, steam explosion, and ultrasonic vibration. Mechanical treatments are considered to be inefficient in the modification or processing of fiber surface properties and removal of non-cellulosic substances (Ganan et al 2004;Rahman and Itoh 2011). On the other hand, these mechanical methods are environmentally friendly and economical because they don't require chemical usage.…”

Tururi palm fibrous material (Manicaria saccifera Gaertn.) characterization

“…The damage to the cellular structures is visible, such as the deformation of cell shape. 27 The microscopic cross-sections and longitudinal sections of the tururi fibrous material are presented in Figures 4(a) and 4(b) respectively. The longitudinal section (Figure 4(b)) shows the non-woven net pattern fiber organization of the tururi fibrous material.…”

Estudos das caracterísitcas físico-químicas de fibras vegetais têxteis de espécies de Malvaceae

“…O exame das seções transversais por microscopia óptica também se presta a avaliação da integridade da estrutura celular das fibras e da adequação do tempo de maceração para a extração destas. Em caso de ultra-maceração, são visíveis os danos às estruturas celulares, tais como deformação do formato celular ou formação de grandes orifícios oriundos do dano a essas estruturas (GAÑÁN et al, 2004). No presente estudo, as microscopias ópticas da seção transversal, correspondentes às espécies analisadas, mostram plena integridade de suas estruturas celulares.…”