Effect of the Fiber Treatment on the Stiffness of Date Palm Fiber Reinforced PP Composites: Macro and Micromechanical Evaluation of the Young’s Modulus

Abstract

The present work aims at determining the potential of date palm wastes to be applied as reinforcement in polypropylene. For this, fibers were separated from the raw biomass via mechanical defibration in Sprout Waldron equipment. Then, three different treatment strategies were adopted on the fibers, being (i) mechanical, (ii) chemical with NaOH, and (iii) enzymatical with xylanases and pectinases. Fibers were characterized in terms of chemical composition, morphology and SEM. Additionally, PP was reinforced with date palm fibers and the composites’ stiffness was evaluated. The analysis was performed from a macro and micro mechanical viewpoint. The incorporation of 40 and 60 wt.% of DPF-E enhanced the Young’s modulus of PP by 205 and 308%, respectively. The potential of enzymatically treated fibers to replace glass fibers in composites was studied, exhibiting similar stiffening abilities at 60 wt.% of date palm fiber (6.48 GPa) and 40% of glass fibers (6.85 GPa). The intrinsic Young’s modulus of the fibers was set at values around 16, 20 and 24 GPa for mechanical, chemical and enzymatic fibers. From the micromechanical analysis, the efficiency of the reinforcement as well as the contribution of the length and orientation to the Young’s modulus of the composite was evaluated.

Effective Young’s Modulus Estimation of Natural Fibers through Micromechanical Models: The Case of Henequen Fibers Reinforced-PP Composites

“…Then, the presence of MAPP did not substantially affect Young's modulus of the composites. This agrees with the literature which states that the stiffness of composite materials should not be affected by the quality at the interfacial boundary, and thus, by the presence of coupling agents [39,41].…”

“…Such issues can be avoided, or at least mitigated, by incorporating maleic anhydride grafted polypropylene (MAPP) into the composites, which may act as a bridge between the lignocellulosic and polymeric phases. MAPP's interaction mechanism has been thoroughly illustrated and discussed in previous works [39,40]. Figure 3 shows the effect of different MAPP percentages (from 2 to 8 wt.%) on specific energy consumption (SEC) and the tensile properties (strength, Young's modulus, and elongation at break) for 40 wt.% henequen fibers-reinforced PP composites.…”

Comparison of Young’s Modulus of Continuous and Aligned Lignocellulosic Jute and Mallow Fibers Reinforced Polyester Composites Determined Both Experimentally and from Theoretical Prediction Models

“…It is known that the mechanical properties of a composite depend on the intrinsic properties of its phases. In this way, when determining the individual properties of the reinforcement fibers and the matrix, we can apply to the existing micromechanical models that proved to be useful and reliable to calculate the intrinsic properties [ 31 , 32 , 33 ]. All models used in this paper are presented below and were used to predict the Young’s modulus of unidirectional continuous fiber-reinforced composites in the loading direction.…”

Stiffening Potential of Lignocellulosic Fibers in Fully Biobased Composites: The Case of Abaca Strands, Spruce TMP Fibers, Recycled Fibers from ONP, and Barley TMP Fibers

“…The Reuss model defines a situation where each fiber is longitudinally aligned with the stress direction, whereas the fibers are transversally aligned with the stress direction in the Voigt model. The models have been illustrated in previous works [ 44 ]. The parallel, series, and Hirsch models are computed according to Equation (3), Equation (4), and Equation (5), respectively.…”