Mechanical behavior and physicochemical modifications in lignosulfonate-treated fique (Furcraea Andina) fibers

One of the most frequent problems in biocomposites is the physical/chemical incompatibility between natural lignocellulosic fibers (NLF) and the matrix. Physical and/or chemical treatments are the most common approach to improve interface properties. Seeking for environmentally friendly treatments, lignosulfonates (LSs) have been considered for surface modification of NLF due to their amphiphilic properties. Thus, the objective of the present work is to evaluate the influence of sodium LS (SLS) treatment protocols in the properties and mechanical behavior of fique (Furcraea Andina) fibers. X-ray diffraction (XRD), Thermogravimetric (TGA) and spectroscopic (FTIR) analyzes were performed, as well as optical microscopy, scanning electron microscopy (SEM), fiber-diameter measurements and tensile tests. The results showed efficient surface cleaning from extractives and absorption of saline and aromatic components from SLS. Partial removal of lignin and hemicellulose was observed as well, manifested by an increasing in fiber crystallinity, decreasing in the intensity of the characteristic bands of C=O (acetyl and ester) and p-hydroxy-phenyl, and displacement in the temperature of cellulose pyrolysis to lower temperatures. These phenomena were stronger in the fibers with longer exposures to SLS. The SLS treatment protocols produce a narrower strength distribution, improving the reliability of the fibers relative to its mechanical behavior.