RESUMO
This study aims to enhance value addition to agricultural byproducts to produce composites by the solution casting technique. It is well known that PLA is moisture-sensitive and deforms at high temperatures, which limits its use in some applications. When blending with plant-based fibers, the weak point is the poor filler-matrix interface. For this reason, surface modification was carried out on hemp and flax fibers via acetylation and alkaline treatments. The fibers were milled to obtain two particle sizes of <75 µm and 149-210 µm and were blended with poly (lactic) acid at different loadings (0, 2.5%, 5%, 10%, 20%, and 30%) to form a composite film The films were characterized for their spectroscopy, physical, and mechanical properties. All the film specimens showed C-O/O-H groups and the π-π interaction in untreated flax fillers showed lignin phenolic rings in the films. It was noticed that the maximum degradation temperature occurred at 362.5 °C. The highest WVPs for untreated, alkali-treated, and acetylation-treated composites were 20 × 10-7 g·m/m2 Pa·s (PLA/hemp30), 7.0 × 10-7 g·m/m2 Pa·s (PLA/hemp30), and 22 × 10-7 g·m/m2 Pa·s (PLA/hemp30), respectively. Increasing the filler content caused an increase in the color difference of the composite film compared with that of the neat PLA. Alkali-treated PLA/flax composites showed significant improvement in their tensile strength, elongation at break, and Young's modulus at a 2.5 or 5% filler loading. An increase in the filler loadings caused a significant increase in the moisture absorbed, whereas the water contact angle decreased with an increasing filler concentration. Flax- and hemp-induced PLA-based composite films with 5 wt.% loadings showed a more stable compromise in all the examined properties and are expected to provide unique industrial applications with satisfactory performance.
RESUMO
One of the most important environmental issues in the world today is the problem of air pollution, which includes particulate matter (PM) and greenhouse gases (mainly CO2). The production of efficient sustainable filters to overcome this concern as well as to provide an alternative to synthetic petroleum-based filters remains a demanding challenge. The purpose of this research was to first produce novel cellulose nanofibers (CNF) based nanofilter from a combination of CNF and chitosan (CS) and then evaluate its applicability for air purification. A number of structural and chemical properties as well as CO2 and PM adsorption efficiency of the modified CNF, were determined using advanced characterization techniques. After pretests, we determined the optimum loading for the CS was 1 wt%, and upon producing the samples, the CNF loadings (1, 1.5, and 2 wt%) were chosen as one variable. For particle absorption, the PM sizes (0.1, 0.3, 0.5, and 2.5 µm) were kept as other variables. Based on SEM results, we concluded the higher the concentration of CNF the higher the specific surface area and the lower the porosity and the diameter of the pores, which was confirmed by the BET test. Furthermore, the results showed that increasing the concentration of modified CNFs increases the adsorption rate of CO2 and PM and that the highest adsorption of CO2 and PM belonged to the 2% modified CNF.
