Literatura académica sobre el tema "Staple recycled fiber/matrix interfaces"

Increasing waste streams of carbon fibers (CF) and carbon fiber reinforced plastics (CFRP) lead to increasing need for recycling and to growing amounts of recycled carbon fibers. A main issue in current research for carbon fiber recycling is the reuse of regained fibers. Carbon staple fibers such as recycled fibers hold big potential for mechanical properties of lightweight parts, if used properly. Applying recycled CF (rCF) as milled reinforcement fibers or as nonwoven in carbon fiber reinforced plastic leads to a poor yield of mechanical proper due to low fiber orientation, limitations in fiber volume content or due to short fiber length. The rC staple fiber tape presents a more efficient approach. Recycled carbon fibers are blended with 50 wt. % thermoplastic nylon 6 fibers and processed through a roller card to a sliver, which is a linear fibrous intermediate. The sliver is continuously drawn, formed, heated and consolidated to the thermoplastic rC staple fiber tape. The tape is similar to common carbon fiber tapes or to continuous tows but has different positive properties, such as high fiber orientation, homogeneous blend of fiber and matrix and suitability for deep drawing.

This study investigates the influence of a hot press process on the properties of hemp fiber-reinforced organo sheets. Plain-woven fabric made from hemp staple fiber yarns is used as textile reinforcement, together with a recycled poly-lactic acid (PLA) matrix. Process pressure and temperature are considered with three factor levels for each parameter. The parameter influence is examined based on the B-factor model, which considers the temperature-dependent viscosity of the polymer, as well as the process pressure for the calculation of a dimensionless value. Increasing these parameters theoretically promotes improvements in impregnation. This study found that the considered recycled polymer only allows a narrow corridor to achieve adequate impregnation quality alongside optimal bending properties. Temperatures below 170 °C impede impregnation due to the high melt viscosity, while temperature increases to 185 °C show the first signs of thermal degradation, with reduced bending modulus and strength. A comparison with hemp fiber-reinforced virgin polypropylene, manufactured with identical process parameters, showed that this reduction can be mainly attributed to polymer degradation rather than reduction in fiber properties. The process pressure should be at least 1.5 MPa to allow for sufficient compaction of the textile stack, thus reducing theoretical pore volume content to a minimum.

The utilization of waste fibers in the production of reinforced concrete materials offers several advantages, including reducing environmental strain and socio-economic impacts associated with composite waste, as well as enhancing material performance. This study focuses on the development of cementitious mortars using secondary waste carbon fibers, which are by-products derived from the industrial conversion of recycled fibers into woven/non-woven fabrics. The research primarily addresses the challenge of achieving adequate dispersion of these recycled fibers within the matrix due to their agglomerate-like structure. To address this issue, a deagglomeration treatment employing nanoclay conditioning was developed. The functionalization with nanoclay aimed to promote a more uniform distribution of the reinforcement and enhance compatibility with the cementitious matrix. Various fiber weight percentages (ranging from 0.5 w/w% to 1 w/w% relative to the cement binder) were incorporated into the fiber-reinforced mix designs, both with and without nanoceramic treatment. The influence of the reinforcing fibers and the compatibility effects of nanoclay were investigated through a comprehensive experimental analysis that included mechanical characterization and microstructural investigation. The effectiveness of the nanoceramic conditioning was confirmed by a significant increase in flexural strength performance for the sample incorporating 0.75 w/w% of waste fibers, surpassing 76% compared to the control material and exceeding 100% compared to the fiber-reinforced mortar incorporating unconditioned carbon fibers. Furthermore, the addition of nanoclay-conditioned carbon fibers positively impacted compression strength performance (+13% as the maximum strength increment for the mortar with 0.75 w/w% of secondary waste carbon fibers) and microstructural characteristics of the samples. However, further investigation is required to address challenges related to the engineering properties of these cementitious composites, particularly with respect to impact resistance and durability properties.

This work presents the physical-thermal and mechanical characterization of a low-density polyethylene (LDPE)-Al matrix composite material that was obtained from reinforcing recycled (post-consumer) long-life Tetra Pak packages with fique natural fibers from southwestern Colombia. The fique was subjected to three chemical treatments to modify its surface (alkalinization, silanization and pre-impregnation with polyethylene) to increase the quality of its interfaces. Additionally, panels with 10%, 20%, and 30% v/v of fiber were manufactured by the hot compression molding. The mechanical properties of the different composite materials showed that the pre-impregnation treatment promoted a significant increase in the tensile and flexural properties with respect to the fiber-reinforced composite without surface modification. Additionally, in materials with 30% fibers that were treated with pre-impregnation, there was a decrease in the water absorption capacity of 53.15% when compared to composites made with 30% native fibers. Finally, increases in the fiber content mainly caused better mechanical performances, which increased as a direct function of the amount of fique incorporated.

This work involved a study of polymer-fiber composites as biodegradable packaging made from recycled polyethylene (r-PE) and chemical-treated cotton fabric waste micro fibers. A compatibilizer, polyethylene-graft-maleic anhydride (PE-g-MA), was used to improve properties of the composites. Factors affecting composite properties were investigated including % PE-g-MA loading, and % fiber loading. The fiber composites were prepared by melt-blending technique. The materials were first mixed by a twin-screw extruder and shaped into samples by an extrusion blow molding machine. The samples were then characterized for mechanical, and morphological properties. It was found that properties of the composites were improved by adding the compatibilizer. Optimum properties of the composites were found at 10% (wt%) PE-g-MA loading. It was also revealed that tensile strength and modulus was found to increase as the % fiber loading was increased. SEM micrographs confirmed that interfacial bonding between the cellulose fibers and the r-PE matrix was enhanced as fewer voids at the interfaces were revealed by adding the PE-g-MA compatibilizer to the composites. Film formation occurred on all composites even if the polymer itself was inert biodegradation. The microbial colonization affected mainly of surface properties r-PE composites while changes were monitored also in the bulk properties of cellulose microfiber.

Millions of tons of glass fiber reinforced polymer (GFRP) waste have been steadily generated from end-of-life wind turbine blades and many other GFRP composites prevalent in everyday life, with limited reuse options. Recycled GFRP (rGFRP) by mechanical processing could be used in mortar and concrete as fibers or fillers. Maintaining the composite nature of rGFRP with a high fiber content is paramount to increased mechanical properties for concrete. In this study, high-modulus rGFRP particles were produced in three small, medium, and large relative sizes by hammer milling and screening. Small and medium rGFRPs were used in 1, 2, 3%, and large rGFRP in 1, 2, 3, 5, and 7% volume replacing sand in mortar. Almost all rGFRP-mortars showed significant improvement in flexural strength with their high modulus. All size groups of rGFRP progressively showed higher fracture toughness at higher amounts. Within the large group, 5 and 7%Vol had flexural toughness of about 2.00J compared with 0.75J of 3%Vol. Large rGFRP at 5 and 7%Vol offered nearly 60% and 70% 28 day equivalent flexural ratio. Micrographs of rGFRP–matrix interfaces from fracture faces showed rGFRP was well embedded within the matrix, provided bridging and deflecting of microcracks, and failed in pullout or rupture modes. Fly ash and silica fume had a positive synergy with 3%Vol large rGFRP and improved its flexural toughness from 0.75J to 1.12 and 1.00J, respectively. The investigated recycling process and sizes of rGFRP shreds showed great promise in this exploratory study and are recommended for further evaluation for highway and bridge concrete.

Valorization of wheat straw fiber/recycled polypropylene nanocomposites was investigated through studying the individual and combined effects of organically modified montmorillonite (OMMT) and alkali treatments on the given composites. FTIR spectra indicated the reduction of wheat straw fibers' hydroxyl groups due to hemicellulose removal resulting from alkali treatment. There were also trace diminutions in C-O peak intensities due to the degradation of little amounts of lignin. X-ray analysis revealed the intercalation of nanoclay in the polymer matrix. The improved interaction of fiber-polymer interfaces brought about by alkali treatment was also confirmed by scanning electron microscopy. The water absorption and thickness swelling properties of the nanocomposites were improved due to the barrier properties of nanoclay against water ingress. The flexural strength and modulus of elasticity increased by the individual, and likewise combined treatments. Thermogravimetric analysis demonstrated that the temperatures of first and second stages of composites' thermal degradation increased via the formation of a carbonized char layer thermally insulating the deeper composite layers. Differential scanning calorimetry showed some slight increases in the melting temperature, melting enthalpy, crystallisation temperature, crystallisation enthalpy, and crystallinity index of the treated composites due to the nucleating effect of nanofillers. The overall results showed that the combined treatment of OMMT and NaOH (vs. the individual ones) could significantly improve the overall properties of the studied composites. This was due to some interesting synergistic effects of the given treatments converting the wheat straw fiber/recycled polypropylene nanocomposites to high performance materials of choice for industry.

This study was aimed at evaluating the individual and combined effects of organically modified nanoclay cloisite 20A and alkali treatments on the valorization of totally waste-based bagasse fiber/recycled polypropylene nanocomposites. FTIR spectra indicated the reduction of bagasse fibers’ hydroxyl moieties due to hemicellulose removal resulting from alkali treatment. There were also trace diminutions in C-O peak intensities due to the degradation of little amounts of lignin. X-ray Scattering revealed the intercalation of nanoclay in the polymer matrix. The improved interaction of fiber-polymer interfaces brought about by alkali treatment was also confirmed by scanning electron microscopy. The physical properties of the nanocomposites were improved due to the barrier properties of nanoclay against water ingress. The flexural strength and modulus of elasticity increased by both individual and combined treatments; however, the impact strength decreased by the individual treatments. Thermogravimetric analysis demonstrated that the temperatures of first and second stages of composites’ thermal degradation increased due to the treatments via the formation of a carbonized char layer thermally insulating the deeper composite layers. Differential scanning calorimetry showed some slight increases in the melting temperature, melting enthalpy, crystallisation temperature, crystallisation enthalpy, and crystallinity index of the treated composite formulations due to the nucleating effect of nanofillers. The overall results confirmed that the combination of nanoclay cloisite 20A and NaOH treatments could significantly improve the overall properties of the studied composites. This was due to some interesting synergistic effects of the given treatments on the nanocomposites converting the bagasse/recycled PP composites to high performance materials of choice.

Depuis leur industrialisation, la production de composites en fibres de carbone augmente de façon continue. Lors du recyclage des composites à fibres de carbone, seules les fibres seront recyclées. La « suppression » de la matrice est réalisée par pyrolyse, solvolyse ou vapo-thermolyse, procédés qui n’entraînent que peu de dégradation des fibres. Afin de susciter une demande pour les fibres de carbone recyclées, il faut donner de la valeur ajoutée aux fibres recyclées en démontrant la faisabilité de fabriquer des pièces composites (fibre recyclée+matrice) de haute qualité.Les architectures de fibres recyclées semi longues avec un très bon alignement ont été produites par la technologie de réalignement brevetée du laboratoire qui permet d’assurer une exploitation optimale des propriétés des fibres de carbone recyclées. Dans le but de maîtriser et d’optimiser les propriétés du nouveau composite (à fibres discontinues), les mécanismes de transfert de charge entre fibres ont été étudiés, et les propriétés utiles de la matrice ont été identifiées. Une attention particulière a été portée au calcul de la longueur de transfert de charge entre deux fibres discontinues en fonction des propriétés de l'interface fibre recyclée / matrice thermoplastique. En effet, notre objectif est non seulement de rechercher des solutions optimales en termes de résistance mais aussi des solutions qui permettent de limiter l’impact environnemental, d’où notre choix des matrices thermoplastiques (y compris recyclées) pour cette étude.Tous les résultats des simulations numériques ont été validés par comparaison avec des résultats expérimentaux. De plus des composites fibres de carbone recyclées/matrice thermoplastique (PA6 et PC) ont été mis en œuvre et testés. Ces matériaux présentent des taux de fibres supérieurs à 50% et offrent de meilleures propriétés mécaniques que les mêmes matériaux avec matrice epoxy.Une analyse environnementale a été propsée sur l’exemple d’une pale d’éolienne portative en comparant les impacts de la matière première, de la fabrication et de la fin de vie d’une pièce réalisée avec différents matériaux (alliage léger, composite fibres de verre, composites à fibres recyclées). Cela démontre l’intérêt des fibres de carbone recyclées associées à une matrice thermoplastique recyclée, pour minimiser l’impact environnemental tout en maximisant les performances mécaniques
Since their industrialization, the production of carbon fiber composites is continuously increasing. When recycling carbon fiber composites, only the fibers are recycled. The matrix is "removed" by pyrolysis, solvolysis or vapour-thermolysis, processes that cause little degradation of the fibres. In order to create a demand for recycled carbon fibers, it is necessary to add value to recycled fibers by demonstrating the feasibility of manufacturing high quality composite parts (recycled fiber + matrix).Semi-long recycled fiber architectures with very good alignment were produced by the laboratory's patented realignment technology that ensures optimal exploitation of recycled carbon fiber properties. In order to control and optimize the properties of the new composite (staple fiber), the mechanisms of load transfer between fibers were studied, and the useful properties of the matrix were identified. Particular attention has been paid to the calculation of the load transfer length between two staple fibers as a function of the properties of the recycled fiber/thermoplastic matrix interface. Indeed, our objective is not only to find optimal solutions in terms of strength but also solutions that allow to limit the environmental impact, hence our choice of thermoplastic matrices (including recycled) for this study.All the results of the numerical simulations were validated by comparison with experimental results. In addition, recycled carbon fiber/thermoplastic matrix composites (PA6 and PC) were implemented and tested. These materials have fiber contents higher than 50% and offer better mechanical properties than the same materials with epoxy matrix.An environmental analysis was performed on the example of a portable wind turbine blade by comparing the impacts of the raw material, manufacturing and end of life of a part made with different materials (light alloy, glass fiber composite, recycled fiber composites). This demonstrates the interest of recycled carbon fibers associated with a recycled thermoplastic matrix, to minimize the environmental impact while maximizing mechanical performance