Impact of Alkaline Hornification in Jute Fibers on the Tensile Strength

Abstract

Wetting and drying cycles are usually used in the paper and cellulose industry aiming to achieve a reduction in the water absorption capacity of lignocellulosic fibers. This procedure stiffens the polymeric structure of the fiber-cells (process known as hornification) resulting in a higher dimensional stability. Several authors have proposed treatments in natural fibers, including hornification, that modifies the surface of the fibers and increase the mechanical behavior. The present study presents a comprehensive analysis of the influence of alkaline hornification with calcium hydroxide 0.7% (1 cycle) on the structure modification, mechanical response, durability performance and bond behavior of jute fibers. The intrinsic changes on the fiber structure as well as their physical and chemical characteristics were evaluated through analytical techniques such as X-ray diffraction (XRD), Thermogravimetry (TGA), Fourier Transformed Infrared (FTIR) and Scanning Electronic Microscope (SEM), while their mechanical response was evaluated with direct tensile tests. The obtained results indicate that the hornification process removes partially the lignin and hemicelluloses from jute fibers, which changes the fiber properties, increasing their crystallinity, altering their morphology, by an increase in the thickness of the secondary fiber wall and reduction of the lumen, and increasing their mechanical resistance.