Study on two eco-friendly surface treatments on Luffa cylindrica for development of reinforcement and processing materials

Abstract

The development of new materials or the improvement of their mechanical properties is a constant challenge in science. Numerous researchers have increasingly concentrated efforts to obtain new and more environmentally friendly materials using natural fibers, which, to be used in engineering applications, usually have to undergo thermochemical treatments. This work aims to evaluate and compare the effects of two low-cost and low-impact thermochemical treatments on Luffa cylindrica (LC) fibers to verify why different mechanical strengths are reached when applying these variations in the production of compressed earth blocks. Samples of LC fibers in three conditions were studied, LC fibers without treatment or natural LC fibers (LN), fibers treated with boiled water (LW) and fibers treated with sodium hydroxide (LS). Samples were analyzed by SEM/EDS to verify surface changes and chemical composition. The lignin, hemicellulose, amorphous and crystalline cellulose structures were determined by FTIR. XRD technique was used to determine the amorphous and crystalline phases, as well as the crystallinity index and the crystallite size. Both treatments decreased the crystallinity index, but the sodium hydroxide treatment has given a crystallinity higher than that of the water treatment. However, the water treatment cannot be ignored. Perhaps more convenient results can be achieved by varying the water treatment time.