Ensete fiber is a natural material extracted from E. ventricosum plants which is widely cultivated for food. This study is the first attempt to develop its composite by improving its compatibility ...with high density polyethylene (HDPE). The premixed composite constituents were melt-compounded by twin-screw extrusion and granulated. Composite plates were molded using hot-press machine. The effect of grafting maleic anhydride to HDPE and varying fiber loading on composite properties were investigated. Increasing ensete fiber loading has resulted in the composites being stiffer and harder leading to a decrease in its elongation at break. The addition of 5 wt% compatibilizer into 25 wt% ensete fiber-filled HDPE improved the fiber-matrix adhesion. Its tensile strength, flexural strength and impact absorption energy increased by nearly 43%, 46%, and 56% respectively when compared to composites with the same fiber loading and without compatibilizer. Morphological analysis from microscopic images of tensile fracture surfaces enlightened the interfacial adhesion to support these test results. The composites density, water absorption and melt flow index were also compared. The results show that ensete fiber-HDPE composite could be used as construction and building materials, low-density furniture, and moldable structures in need of design flexibility.
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•Ensete fiber - HDPE thermoplastic composites were developed and their performance was analyzed.•High ensete fiber loading makes stiffer and harder composite with a decreasein elongation at break.•Maleic anhydride grafted polyethylene compatibilizer substantially improved mechanical and physical properties.•Grafting of compatibilizer, twin screw compounding, hot press molding approach suits large scale production of biocomposites.
The present research investigated previously unexplored attributes of 3D printed continuous fiberglass reinforced Nylon composites, Drop-weight and pendulum (Charpy and Izod) impact resistance ...including their failure mechanisms with a view to assessing their suitability for prospective high-performance applications such as aerospace, automobile and building industries. The composites were printed with different cellular structures (triangular, hexagonal, rectangular and solid) and three distinct fiber orientations (0/0/0/0, 0/90/0/90 and 0/45/90/-45). Results of the impact assessment of the developed composites exhibited substantial performance when compared to traditional 3D orthogonal plain-woven composites indicating 3D printing process as a promising composite fabrication technology. The effect of fiber orientation was very dominant towards dictating mechanical properties; cross-lay samples (0/90/0/90) absorbed the highest Drop-weigh impact energy followed by quasi-isotropic (0/45/90/-45) and unidirectional (0/0/0/0) composites, while the highest pendulum impact energy was showed by unidirectional composites, followed by cross-lay and quasi-isotropic samples. Incorporation of cellular structure had some effect on the properties measured and composite weight reduction; however, relative contribution of different structures was confounding associating a lot of factors that warn further research.
A sustainable power supply for a wide range of applications, such as powering sensors for structural health monitoring and wireless sensoring nodes for data transmission and communication used in ...unmanned air vehicles, automobiles, renewable energy sectors, and smart city technologies, is targeted. This paper presents an experimental and numerical study that describes an innovative technique to harvest energy resulted from environmental vibrations. A piezoelectric energy harvester was integrated onto a carbon fibre reinforced polymer (CFRP) laminate structure using the co-curing method. The integrated composite with the energy harvester was lightweight, flexible and provided robust and reliable energy outcomes, which can be used to power different low-powered wireless sensing nodes. A normalised power density of 97 μW cm−3m−2s4 was obtained from resonance frequency of 46 Hz sinusoidal waves at amplitude of 0.2 g; while the representative environmental vibration waves in various applications (aerospace, automotive, machine and bridge infrastructure) were experimentally and numerically investigated to find out the energy that can be harvested by such a multifunctional composite structure. The results showed the energy harvested at different vibration input from various industrial sectors could be sufficient to power an autonomous structural health monitoring system and wireless communications by the designed composite structure.
While aramid fibers have been innovative for ballistic protection because of their high energy absorption, minimal usage has been applied to continuous fiber reinforced polymer (CFRP) composites in ...structural applications. One of the challenges with aramid fibers results from their processing, which yields smooth and chemically inert surfaces that limit the ability of the fibers to adhere to polymeric matrices. Here, it is shown that aramid nanofibers can adhere to the surface of macroscale aramid reinforcements to improve the strength of the composite interface and reinforce the matrix as well. Aramid nanofibers are formed through the dissolution of aramid fibers followed by isolation and dispersion into an epoxy matrix. When employed in CFRP, aramid nanofibers prove to be effective reinforcement agents through improvement in both matrix properties as well as modifying the interfacial shear strength, which leads to improved interlaminar shear strength and fracture toughness. The interface enhancements are attributed to hydrogen bonding and π-π coordination between the aramid nanofibers and the macro fibers providing improved transfer load from the fiber to the matrix. This work demonstrates that aramid nanofibers may provide the robust mechanical properties that are necessary for structural applications while utilizing a cost-effective and convenient nanoscale building block.
Eco‐friendly composite made of Timoho Fiber (TF) continuously developed to get the best performance to replace plastic‐based synthetic fibers. This study focuses on investigating physical ...characteristics, mechanical properties, thermal analysis, and the morphology of TF‐reinforced polyester composites by adding organic (egg shell powder‐ESP) and inorganic (aluminum powder‐AP) fillers. Hot press method was used in the composite fabrication with considered volume fraction of TF, organic, and inorganic fillers. The results showed that the density of TF‐polyester composites decreases with the increasing volume fraction of the fibers. For additional fillers, it was shown that AP was more effective to be used to improve density than ESP. The tensile and impact strength of the composite increased with increasing TF volume. However, the addition of ESP and AP fillers into the composite caused different mechanical characteristics. Filler addition increased the elasticity modulus, toughness, thermal resistance increased, while the tensile strength decreased. ESP and AP fillers provided the best thermal resistance due to the relatively high thermal conductivity of ±1700°C compared to composites without fillers and amorphous ESP fillers. SEM observation supported the analysis of TF‐polyester composite mechanical characteristics.
Eggshells are a potentially polluting industrial waste that are disposed of as landfill which has proven to be hazardous to the environment. The usage of chicken eggshells as a biofiller for polymer ...matrix composites instead of its disposal as landfill has proven advantageous in various studies. On the other hand, using eggshells as a filler material to replace inorganic calcium carbonate usage would be another environment friendly act. The present study is focused on studying the effects of eggshell filler addition and post-curing on polymer composites which could be utilised for domestic applications. Herein, uncarbonised and carbonised eggshell filler material were processed from waste eggshells. Hybridisation of the carbonised and uncarbonised eggshell filler was carried out. All three variants of eggshell fillers (10 wt.%) were used in the fabrication of composites. A hand lay-up technique was employed in the fabrication of unfilled composites along with three variants of filled composites, namely, uncarbonised, carbonised, and hybrid eggshell filled composites. The fabricated and cured composites were further subjected to post-curing at a temperature of 60 °C for a period of 2 h. All four variants of post-cured composites were then subjected to mechanical testing according to American Society for Testing and Materials (ASTM) standards. The tests revealed that all three variants of filled composites possess better mechanical properties in comparison with unfilled composites. Further, in comparison with unfilled composites, the carbonised eggshell filled composites showcased 42% and 49% improvement in flexural and tensile properties, respectively. The modes of failure of the specimens were observed and tabulated. SEM imaging revealed that the eggshell filler contributed to the strengths of the composites by means of arresting and deviating cracks. It was also observed that the post-cured specimens displayed improved properties when compared with our previous studies on non-post-cured specimens. In summary, the study showcased the benefits of eggshell filler addition and the post-curing of polymer composites.
Industries have been longing for highly thermally conductive polymer materials to cool the heating cores in modern electronics. Graphene-reinforced thermoplastic polymer, though supporting the mature ...technologies in producing heat sinks and plastic shells applications, often fails to realize its full potential in thermal conductivity (TC) due to the limited graphene loading and poor filler dispersion. Aiming at improving graphene/polyamide 6(PA6) interface, a filler/polymer compatibilization approach through grafting polyamide-miscible polyether components on graphene sheets (GSs) is proposed in this work through sequential dopamine and silane treatment. The PA6 composites filled with controlled loading of treated and untreated GSs were fabricated through extruding process. Compared to unmodified GSs, drastically reduced melt viscosity and enhanced filler dispersion are realized in modified GSs filled PA6 composites allowing further loading of GSs up to 28 wt% that enables the unprecedented out-of-plane TC of 6.13 W m−1 K−1. Besides, effective medium theory simulations suggest the significantly reduced interfacial thermal resistance in treated GSs filled composites at above percolation threshold, indicating the formation of thermal conduction network in these samples owing to the homogeneously distributed fillers. These results address the significance of graphene compatibilization approach in producing processible, highly loaded and well dispersed GSs/PA6 composites towards the design and application of highly thermally conductive materials for thermal management in advanced electronics packaging.
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Stretchable strain sensors have promising potentials in wearable electronics for human motion detection, health monitoring and so on. A reliable strain sensor with high flexibility and good stability ...should be designed to detect human joints motions with a large deformation. Here, a simple and facile solution mixing-casting method was adopted to fabricate a highly stretchable strain sensor based on composites mixing polydimethylsiloxane (PDMS) with hybrid carbon nanotubes (CNTs) and carbon black (CB) conductive nanofillers (CNTs-CB). Bridged and overlapped hybrid CNTs-CB nanofillers structure was achieved in the composite on the basis of the morphology observation. In monotonic stretching test, the CNTs-CB/PDMS composites strain sensors exhibited high stretchability, strain-dependent sensitivity in a wide strain sensing range (ca. 300% strain) and an excellent linear current-voltage behavior. During stretching-releasing cycles, the strain sensors presented excellent repeatability, good stability and superior durability (2500 cycles at 200% strain). Combined with the above outstanding strain sensing performances, the fabricated stretchable strain sensors were attached onto different joints of human body to monitor the corresponding human motions, demonstrating their attractive perspective in large human motions detection.
Abstract
Natural fiber reinforced polymer composites (NFRPCs) have emerged as promising eco‐friendly alternatives over conventional synthetic fiber composites due to their inherent biodegradability, ...renewability, low environmental impact, and lightweight properties. It has been seen a significant growth in both invention and innovation in the field of NFRPCs. Natural fibers (NFs) reduce the cost of the material by 5%, the weight of the composite by 10%, and the energy required for production by 80%. In terms of thermal, and acoustic properties, NFs can successfully compete with synthetic fibers. As a result, the development of NFRPCs for industrial use has increased significantly in the past decade to meet the growing demands of industrial sectors. To improve the thermal and acoustic properties of NFRPCs, researchers have done a lot of investigation. The aim of the current review is to provide a comprehensive analysis of the existing literature on the thermal and acoustic properties of natural fiber reinforced polymer composites. Thermal properties such as thermal conductivity, TGA, DSC, DMA, and acoustic properties of natural fiber reinforced composites with several parameters, such as different fiber types, different matrix types, fiber weight ratio, fiber to matrix ratio, chemical treatment of fiber have been summarized and analyzed very concisely. This review also emphasizes a summary of different natural fibers, their chemical compositions, composite preparation, characterizations, and future research directions. This article enables the readers, researchers, and manufacturers to realize several opportunities about the latest developments in NFRPCs for the application of thermal and acoustic purposes.
Highlights
Natural fibers can successfully compete with synthetic fibers, in terms of thermal and acoustic properties.
Thermal properties of natural fiber reinforced composites including thermal conductivity, TGA, DSC, and DMA are summarized.
Acoustic properties of natural fiber reinforced polymer composites are discussed.
Composite materials made of treated fibers result better thermal stability than untreated fiber composites.
Sound absorption coefficient generally increases as fiber content increases.
The aim was to evaluate the effect of short glass-fiber/filler particles proportion on fracture toughness (FT) and flexural strength (FS) of an experimental flowable fiber-reinforced composite ...(Exp-SFRC) with two methacrylate resin formulations. In addition, we wanted to investigate how the fracture-behavior of composite restorations affected by FT values of SFRC-substructure.
Exp-SFRC was prepared by mixing 50wt% of dimethacrylate based resin matrix (bisGMA or UDMA based) to 50wt% of various weight fractions of glass-fiber/particulate filler (0:50, 10:40, 20:30, 30:20, 40:10, 50:0wt%, respectively). FT and FS were determined for each experimental material following standards. Specimens (n=8) were dry stored (37°C for 2 days) before they were tested. Four groups of posterior composite crowns (n=6) composed of different Exp-SFRCs as substructure and surface layer of commercial particulate filler composite were fabricated. Crowns were statically loaded until fracture. Failure modes were visually examined. The results were statistically analysed using ANOVA followed by post hoc Tukey’s test.
ANOVA revealed that ratio of glass-fiber/particulate filler had significant effect (p<0.05) on tested mechanical properties of the Exp-SFRC with both monomer systems. Exp-SFRC (50wt%) had significantly higher FT (2.6MPam1/2) and FS (175.5MPa) (p<0.05) compared to non-reinforced material (1.3MPam1/2, 123MPa). Failure mode analysis of crown restorations revealed that FT value of the substructure directly influenced the failure mode.
This study shows that short glass-fibers can significantly reinforce flowable composite resin and the FT value of SFRC-substructure has prior importance, as it influences the crack arresting mechanism.
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