Valorization of Invasive Plants from Macaronesia as Filler Materials in the Production of Natural Fiber Composites by Rotational Molding

Abstract

This paper compares the mechanical properties of different natural fiber composites produced by rotational molding as a way of waste valorization from campaigns to control invasive plant species in Macaronesia. Rotomolded parts produced with polymeric matrices (polyethylene) and filled with up to 20% by weight of cellulosic fibers obtained from Arundo donax L., Pennisetum setaceum, and Ricinus communis plants were characterized in terms of tensile, flexural, and impact strength. It was found that the sieving of natural fibers allowed for their introduction in higher loadings, from 10 (for un-sieved material) to 20%; fiber size greatly affected the mechanical properties of the final parts, although some combinations were proven not to reduce the mechanical properties of the neat resin. This study is a first approach to the valorization of residues obtained from periodic campaigns of the control of invasive species performed by public authorities, usually at the local level. It is important to highlight that the main objective of this research did not focus on economically profitable activity; instead, it was focused on the reduction of wastes to be disposed from ecosystem maintenance actions and the investment of potential income into preservation policies.

Use of Ricinus communis shredded material as filler in rotational molded parts to improve the bio-disintegration behavior

“…It is observed that the density of the composites is lower than the one obtained for the pure polymer parts, being more significant than the difference for composites with treated fibers. Contrary to what was obtained in this research, other authors reported higher density for the composites with treated fibers than for those with untreated ones [15,16]. This decrease is related to the higher porosity of composites with an increased amount of fiber or having treated fibers, as observed in wall thickness and optical microscope.…”

“…The composites were prepared by dry blending the matrix with the fibers (at 5 and 10% weight for PE and 10% weight for PLA) and then, introduced into a lab-made rotomolding device [16]. This has a rotation rate of 2.30 rpm on the primary axis and 9.14 rpm on the secondary axis.…”

“…Other authors have increased this proportion, reaching up to 30% [1,13] drastic decreases in mechanical behavior. An appropriate selection of particle size distribution [14][15][16] or using compatibilizers [6,17] could reduce this effect. In the last years, with the rise of sustainability concerns and the need to increase the use of resources, several authors have moved on to using alternative raw materials to be used as reinforcement or fillers of composite materials.…”

“…For example, Ortega et al produced composites with 5% w/w of banana and abaca fibers with significant improvements in mechanical properties, except for impact strength [18], while Hejna et al obtained composites with up to 20% w/w of wheat bran, although only those with up to 5% content did not show significant loss of mechanical properties [1]. Buckwheat husk, reed, or bamboo are other materials proposed to broaden the options of using lignocellulosic materials [13,16,19,20]. Other authors introduced in rotomolded parts some fillers traditionally considered waste materials, such as cable covers [21] or copper slag from mining [2].…”

Natural Fibers as an Alternative to Synthetic Fibers in Reinforcement of Geopolymer Matrices: A Comparative Review

“…Another aspect is regarding its release and density at the time of making the mixtures (geopolymers and traditional concrete), which, if performed in the wrong way, can contribute to the increase in the incorporated air content that translates into loss of mechanical properties, this was verified in researches that used coconut fiber in different forms of densification [ 46 ]. Another study evaluated the mechanical properties of different composites of natural fibers in polymeric matrices, proving that fiber size is directly related to the mechanical properties of the produced parts [ 47 ]. A relevant mechanism for the application of natural fibers is related to the selection method adopted, aiming to categorize and compare the main mechanical and thermal properties of the fibers in general, aiming at their better incorporation, one option is the use of additive manufacturing for these applications [ 48 ].…”