Isolation of cellulose nanocrystals from pseudostems of banana plants†
On account of their excellent mechanical properties, cellulose nanocrystals (CNCs) are attracting significant interest as a naturally sourced, renewable and inexpensive component of a broad range of nanomaterials. CNCs can be extracted from virtually any natural cellulosic material, but characteristic properties such as maximum aspect ratio, crystal structure, and crystallinity vary considerably between sources. In this work, the isolation of CNCs from the pseudostems of banana plants was explored. The dried stems from the species musa sapientum linn were first cleaned by Soxhlet extraction, alkali treatment and bleaching and subsequently hydrolyzed to CNCs using sulfuric acid. The hydrolysis time was systematically varied, with the objective to maximize the length (L = 375 ± 100 nm) and aspect ratio (A = 28) of the resulting CNCs. The surface charge density of the CNCs thus isolated was 168 mmol kg−1, the predominant crystal structure was that of cellulose I, and the crystallinity was 74%. In order to elucidate the reinforcing capability of the new CNCs, nanocomposites with an ethylene oxide–epichlorohydrin copolymer were prepared and their mechanical properties were investigated by dynamic mechanical analysis (DMA). A comparison with reference nanocomposites made with CNCs isolated from cotton shows that the new CNCs display a higher reinforcing capability.