Valorization of byproducts of hemp multipurpose crops: short non-aligned bast fibers as a source of nanocellulose

Sara Dalle Vacche; Vijayaletchumy Karunakaran; Alessia Patrucco; Marina Zoccola; Loreleï Douard; Silvia Maria Ronchetti; Marta Gallo; Aigoul Schreier; Yves Leterrier; Julien Bras; Davide Beneventi; Roberta Bongiovanni

arXiv · 2105.11742

Valorization of byproducts of hemp multipurpose crops: short non-aligned bast fibers as a source of nanocellulose

Sara Dalle Vacche·Vijayaletchumy Karunakaran·Alessia Patrucco·Marina Zoccola·Loreleï Douard·Silvia Maria Ronchetti·Marta Gallo·Aigoul Schreier·Yves Leterrier·Julien Bras·Davide Beneventi·Roberta Bongiovanni

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Abstract

Nanocellulose was extracted from short bast fibers, from hemp (Cannabis Sativa L.) plants harvested at seed maturity, non-retted, mechanically decorticated in a defibering apparatus giving non-aligned fibers. A chemical pretreatment with NaOH and HCl allowed the removal of most of the non-cellulosic components of the fibers. No bleaching was performed. The chemically pretreated fibers were then refined in a beater and treated with a cellulase enzyme, before the mechanical defibrillation in an ultrafine friction grinder. The fibers were characterized by microscopy, infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction after each step of the process, to understand the evolution of their morphology and composition. The obtained nanocellulose suspension was composed of rod-like fibrils with widths of 5-12 nm, stacks of nanofibrils with widths of 20-200 nm, and some larger fibers. The crystallinity index was found to increase from 74% for the raw fibers to 80% for the nanocellulose. The nanocellulose retained a yellowish color indicating the presence of some residual lignin. Properties of nanopaper prepared with the hemp nanocellulose were similar to those of nanopapers prepared with wood pulp derived rod-like nanofibrils.

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Sara Dalle Vacche, Vijayaletchumy Karunakaran, Alessia Patrucco, Marina Zoccola, Loreleï Douard, Silvia Maria Ronchetti, Marta Gallo, Aigoul Schreier, Yves Leterrier, Julien Bras, Davide Beneventi, Roberta Bongiovanni. 2021-05-25. Valorization of byproducts of hemp multipurpose crops: short non-aligned bast fibers as a source of nanocellulose. https://arxiv.org/abs/2105.11742

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