Modification of the cellulosic component of hemp fibers using sulfonic acid derivatives: Surface and thermal characterization

•Accessible cellulose and hemicellulose were removed during chemical treatment.•Treated fibers were characterized with improved thermal properties.•Increase in surface hydrophobicity of treated samples.•Reaction influence by steric because of the bulky nature of reagent.•Low temperature, zero organic solvent, and fast reaction times can be used. The aim of this study was to characterize the surface, morphological, and thermal properties of hemp fibers treated with two commercially available, inexpensive, and water soluble sulfonic acid derivatives. Specifically, the cellulosic component of the fibers were targeted, because cellulose is not easily removed during chemical treatment. These acids have the potential to selectively transform the surfaces of natural fibers for composite applications. The proposed method proceeds in the absence of conventional organic solvents and high reaction temperatures. Surface chemical composition and signature were measured using gravimetric analysis, X-ray photoelectron spectroscopy (XPS) and Fourier transform infra-red spectroscopy (FTIR). XPS data from the treated hemp fibers were characterized by measuring the reduction in O/C ratio and an increase in abundance of the CCO signature. FTIR confirmed the reaction with the emergence of peaks characteristic of disubstituted benzene and amino groups. Grafting of the sulfonic derivatives resulted in lower surface polarity. Thermogravimetric analysis revealed that treated fibers were characterized by lower percent degradation between 200 and 300°C, and a higher initial degradation temperature.