Influence of water amount and immersion time on the sisal fibers hornification process

Abstract

Hornification is phenomenon that can be promoted by wetting and drying treatment, which modify the microstructure of the lignocellulosic fibers, by promoting the stiffening of the polymeric structure of the fibercells. This process increases fiber mechanical behaviour and reduces water absorption and dimensional variation. The objective of this research is to investigate the influence of several variables on hornification process such as wetting time, fiber/water ratio and the number of wetting and drying cycles on the treatment and its effect on fibers chemical and mechanical properties. Sisal fibers were used. A pre-treatment of 1 h in water (T = 80 °C) and drying at 40°C was applied. Treatments with 1 and 5 cycles of wet and drying were also studied. In both cases two wetting time was applied (1 h and 3 h at 22 °C) and two fiber/water ratio (1:10 and 1:40). The raw and treated fibers were evaluated by thermogravimetric analysis, infrared spectroscopy, wettability analysis, and tensile test. The results showed that lower fiber/water ratios provide better hornification in sisal fibers. Immersion times of 3 hours was efficient to improve tensile strength, increasing stiffness in all studied cases.