Valorization of Pennisetum setaceum: From Invasive Plant to Fiber Reinforcement of Injected Composites.

During the control campaigns of Pennisetum setaceum (invasive species widespread worldwide), the generated waste has accumulated in landfills. This study investigates its use to obtain P. setaceum fibers for their application as reinforcement of polymeric materials for injection molding, thus facilitating and promoting alternatives for the long-term sustainable management of P. setaceum. The extracted fibers were treated with alkaline, silane, acetic acid, and combined alkaline and silane treatments. Different composites with 20 and 40 wt% of fiber were extruded, and test samples were obtained by injection molding using recycled polyethylene as matrix. The composition of the fibers was determined by gravimetric methods, and contrasted with the analysis of the functional chemical groups using Fourier Transform Infrared Spectroscopy. Increases of up to 47% in the cellulose content of the treated fiber were observed. The thermal degradation was also evaluated using thermogravimetric analysis, which determined an increase in the degradation temperature, from 194 to 230 °C, after the combined alkaline-silane treatment. In order to analyze the differences in the composites, tensile, flexural, and impact properties were evaluated; in addition, differential scanning calorimetry was performed. Regarding the flexural behavior, it was possible to improve the flexural modulus up to 276% compared with that of the unreinforced polymer.

An annual study on plastic accumulation in surface water and sediment cores from the coastline of Tenerife (Canary Island, Spain).

Sediment core samples from high tide lines and in submerged zones as well as surface water samples from eight beaches of Tenerife were analysed. Sampling was conducted over a period of one year in intervals of 5 weeks. The majority of particles were found in the high tide sediment (66%), followed by water samples (23%) and finally in sediment from submerged zones (11%). Regarding the particle amount per volume (items/L), accumulation in sediment samples was statistically higher compared to water samples. Mean values of items/L were higher in high tide sediments. In high tide and water samples, mostly white and transparent particles >1 mm were found. More than 70% were represented by fragments. In sediments from submerged zones, yellow and blue microparticles (<1 mm) were predominant and 61.9% consisted of fibres. Larger particles were mainly identified as PP, PE, PS, PTFE and PVC, while polymer types of smaller particles were more variable.

Environmental Hazards of Giant Reed (Arundo donax L.) in the Macaronesia Region and Its Characterisation as a Potential Source for the Production of Natural Fibre Composites.

This paper summarises the results obtained from the characterisation of giant reed (Arundo donax L.) plant and fibres. The research is part of a project developed in the Macaronesia region, of which the aim is to demonstrate the feasibility of using biomass from invasive plant species in the composites sector as a way of financing control campaigns and habitats conservation labours. An experimental procedure for the extraction of fibre bundles from this plant was developed, and the material obtained was characterised in terms of chemical composition, thermogravimetry and infrared spectra to evaluate its potential application in the production of polymeric composite materials as a strategy for the valorisation of residual biomass from this invasive species in Macaronesia. Thermoplastic matrix composites with fibre content up to 40 wt.% were produced and their mechanical properties under tensile, flexural and impact loading were determined. No references on the preparation of composite materials with polyolefin matrices and giant reed fibres have been found. Results obtained from mechanical tests show a good performance of the manufactured composites, with a significant increase in both flexural and tensile stiffness; the flexural modulus is almost tripled for PE-based composites and rises to 88% with respect to PP matrix. The ultimate flexural strength and the tensile and flexural yield strength are kept at acceptable values compared to neat polymer materials, although ultimate tensile strength and impact resistance are significantly affected when natural fibres are added.

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

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.