Influence of TEMPO-Mediated Oxidation on Properties of Hemp Fibers

Abstract

Hemp fibers are a very interesting natural material for textile and technical applications, but some of these applications require improved and/or specific fiber properties. In order to modify hemp fibers for obtaining high added value products, hemp fibers were oxidized with sodium hypochlorite and a catalytic amount of sodium bromide and 2,2,6,6tetramethylpiperidine-1-oxy radical (TEMPO), under various conditions. The oxidized hemp fibers were analyzed and characterized in terms of chemical composition (lignin and hemicelluloses) and weight loss, fineness, introduced functional groups, sorption (moisture sorption, water retention values, iodine sorption), and mechanical properties (tenacity and elongation). Applied TEMPO-mediated oxidation has been very efficient for simultaneous removal of noncellulosic substances (reduction of lignin content up to 1.95%) and introduction of surface functional groups, i.e., aldehyde (up to 0.415 mmol/g) and carboxyl groups (up to 0.815 mmol/g). The oxidized hemp fibers were finer, with a lower content of lignin and hemicelluloses and with improved water uptake properties.

Hemp-Based Materials for Metal Removal

“…It is estimated that hemp was imported to Europe by nomads in the sixteenth century (Bouloc 2013). In the middle of nineteenth century, hemp cultivation decreased with disappearance of the sailing navy and competition from other natural fibres (cotton, jute…) for textile applications, and later due to intensive development of synthetic fibres (Milanovic et al 2012). In the 1930s, cultivation was forbidden in the vast majority of Western countries due to the fact that hemp and marijuana come from the same genus and species plant (Cannabis sativa L.), and this introduced a lot of confusion and social and political controversies.…”

TEMPO-oxidized cellulose nanofibrils prepared from various plant holocelluloses

“…A hemp bast (Cannabis sativa L. Subsp. sativa) holocellulose was oxidized using the TEMPO/NaBr/NaOCl system in water at pH 10 [14,15]. The obtained TEMPO-oxidized hemp bast holocelluloses were mechanically disintegrated in water to prepare nanofibrils.…”

Investigation on the Durability of PLA Bionanocomposite Fibers Under Hygrothermal Conditions

“…Because of the variation in the fibers fineness, the tensile strength is expressed as tenacity (cN/tex), a specific value related to fineness (force per unit fineness). Fineness in tex (g/km), was determined by dividing the mass of fibers by their known length (Milanovic et al, 2012).…”