Addition of carboxylated styrene-butadiene rubber in cellulose nanofibrils composite films: effect on film production and its performance

Abstract

The main objective of this research was to investigate and discuss the interaction between Eucalyptus sp. cellulose nanofibrils (CNFs) and carboxylated styrene–butadiene rubber (XSBR) to produce composite films with higher deformation capacity. The studied films were evaluated through mechanical, morphological, chemical, and physical analysis. The filmogenic solutions of CNFs 1.5% w/v were prepared with the addition of 0, 0.1, 5, 10, and 20% w/w of XSBR under constant agitation. Composite films were obtained by casting. Thermogravimetry analysis (TGA) indicated heterogeneity of the composite for high concentrations of XSBR due to the second stage of thermal degradation. In addition, Fourier Transform Infrared spectroscopy (FTIR) confirmed a strong interaction between the CNFs and XSBR through hydrogen bonding. X-ray diffraction (XRD) was not the best technique to evaluate the crystallinity of products with high XSBR contents. The addition of XSBR has unchanged the composite tensile strength while increasing strain, especially for 5% XSBR, which elongated 35% more than the plain CNFs films. The XSBR also provided a lower affinity of films to water molecules due to the interaction between CNF/XSBR, reducing the hydrophilicity and water vapor permeability. The films with an addition of XSBR 5% (w/w) maintained their morphology and structure but led to an increase in elasticity, water barrier, and smoother and hydrophobic surface. Therefore, the present study has contributed information on developing more flexible and hydrophobic films.