Research

Jump to: Review

18 pages, 10219 KiB

Open AccessArticle

Analysis of the Mechanical Properties and Damage Mechanism of Carbon Fiber/Epoxy Composites under UV Aging

by Zhongmeng Shi, Chao Zou, Feiyu Zhou and Jianping Zhao

Materials 2022, 15(8), 2919; https://doi.org/10.3390/ma15082919 - 16 Apr 2022

Cited by 12 | Viewed by 3158

The UV durability of carbon fiber composites has been a concern. In this work, UV irradiation on carbon fiber-reinforced polymer (CFRP) materials was performed using an artificial accelerated UV aging chamber to investigate the effect of UV exposure on carbon fiber composites. UV [...] Read more.

The UV durability of carbon fiber composites has been a concern. In this work, UV irradiation on carbon fiber-reinforced polymer (CFRP) materials was performed using an artificial accelerated UV aging chamber to investigate the effect of UV exposure on carbon fiber composites. UV aging caused some of the macromolecular chains on the surface resin to break, resulting in the loss of small molecules and loss of mass. After 80 days of UV irradiation exposure, a significant decline in the macroscopic mechanical properties occurred in the longitudinal direction, with the largest decrease of 23% in longitudinal compressive strength and a decreasing trend in the transverse mechanical properties at the later stage of aging. The microscopic mechanical properties of the CFRP specimens were characterized using nanoindentation, and it was found that UV aging had an embrittlement effect on the matrix, and its hardness/modulus values were higher than the initial values with UV exposure. The fibers were less affected by UV irradiation. Full article

(This article belongs to the Special Issue Feature Collection in Advanced Composites Section)

► Show Figures

Figure 1

19 pages, 6747 KiB

Open AccessArticle

Mechanical Experiments on Concrete with Hybrid Fiber Reinforcement for Structural Rehabilitation

by Muhammad Asharib Shahid, Muhammad Usman Rashid, Nazam Ali, Krisada Chaiyasarn, Panuwat Joyklad and Qudeer Hussain

Materials 2022, 15(8), 2828; https://doi.org/10.3390/ma15082828 - 12 Apr 2022

Cited by 2 | Viewed by 1802

Abstract

Reinforced concrete is used in the construction of bridges, buildings, retaining walls, roads, and other engineered structures. Due to seismic activities, a lot of structures develop seismic cracks. The rehabilitation of such structures is necessary for public safety. The overall aim of this [...] Read more.

Reinforced concrete is used in the construction of bridges, buildings, retaining walls, roads, and other engineered structures. Due to seismic activities, a lot of structures develop seismic cracks. The rehabilitation of such structures is necessary for public safety. The overall aim of this research study was to produce a high-performance hybrid fiber-reinforced concrete (HPHFRC) with enhanced properties as compared to plain high-performance concrete and high-performance fiber-reinforced concrete (HPFRC) for the rehabilitation of bridges and buildings. Kevlar fibers (KF) and glass fibers (GF) with lengths of 35 mm and 25 mm, respectively, were added and hybridized to 1.5% by mass of cement to create hybrid fiber-reinforced concrete mixes. Eight mixes were cast in total. The compressive strength (f′_c), flexural strength (f_r), splitting tensile strength (f_s), and other mechanical properties, i.e., energy absorption and toughness index values, were enhanced in HPHFRC as compared to CM and HPFRC. It was found that the concrete hybridized with 0.75% KF and 0.75% GF (HF-G 0.75 K 0.75) had the most enhanced overall mechanical properties, illustrating its potential to be utilized in the rehabilitation of bridges and structures. Full article

(This article belongs to the Special Issue Feature Collection in Advanced Composites Section)

► Show Figures

Figure 1

22 pages, 5492 KiB

Open AccessEditor’s ChoiceArticle

Fragmentation of Beaded Fibres in a Composite

by Carol Winnifred Rodricks, Israel Greenfeld, Bodo Fiedler and Hanoch Daniel Wagner

Materials 2022, 15(3), 890; https://doi.org/10.3390/ma15030890 - 24 Jan 2022

Cited by 3 | Viewed by 2804

Abstract

The fibre–matrix interface plays an important role in the overall mechanical behaviour of a fibre-reinforced composite, but the classical approach to improving the interface through chemical sizing is bounded by the materials’ properties. By contrast, structural and/or geometrical modification of the interface may [...] Read more.

The fibre–matrix interface plays an important role in the overall mechanical behaviour of a fibre-reinforced composite, but the classical approach to improving the interface through chemical sizing is bounded by the materials’ properties. By contrast, structural and/or geometrical modification of the interface may provide mechanical interlocking and have wider possibilities and benefits. Here we investigate the introduction of polymer beads along the interface of a fibre and validate their contribution by a single fibre fragmentation test. Using glass fibres and the same epoxy system for both matrix and beads, an increase of 17.5% is observed in the interfacial shear strength of the beaded fibres compared to fibres with no polymer beads. This increase should lead to a similar improvement in the strength and toughness of a beaded fibre composite when short fibres are used. The beads were also seen to stabilise the fragmentation process of a fibre by reducing the scatter in fragment density at a given strain. A case could also be made for a critical beads number—4 beads in our experimental system—to describe interfacial shear strength, analogous to a critical length used in fibre composites. Full article

(This article belongs to the Special Issue Feature Collection in Advanced Composites Section)

► Show Figures

Graphical abstract

23 pages, 8106 KiB

Open AccessArticle

Where ppm Quantities of Silsesquioxanes Make a Difference—Silanes and Cage Siloxanes as TiO₂ Dispersants and Stabilizers for Pigmented Epoxy Resins

by Dariusz Brząkalski, Robert E. Przekop, Miłosz Frydrych, Daria Pakuła, Marta Dobrosielska, Bogna Sztorch and Bogdan Marciniec

Materials 2022, 15(2), 494; https://doi.org/10.3390/ma15020494 - 10 Jan 2022

Cited by 8 | Viewed by 1869

Abstract

In this work, silsesquioxane and spherosilicate compounds were assessed as novel organosilicon coupling agents for surface modification of TiO₂ in a green process, and compared with their conventional silane counterparts. The surface-treated TiO₂ particles were then applied in preparation of epoxy [...] Read more.

In this work, silsesquioxane and spherosilicate compounds were assessed as novel organosilicon coupling agents for surface modification of TiO₂ in a green process, and compared with their conventional silane counterparts. The surface-treated TiO₂ particles were then applied in preparation of epoxy (EP) composites and the aspects of pigment dispersion, suspension stability, hiding power, as well as the composite mechanical and thermal properties were discussed. The studied compounds loading was between 0.005–0.015% (50–150 ppm) in respect to the bulk composite mass and resulted in increase of suspension stability and hiding power by over an order of magnitude. It was found that these compounds may be an effective alternative for silane coupling agents, yet due to their low cost and simplicity of production and manipulation, silanes and siloxanes are still the most straight-forward options available. Nonetheless, the obtained findings might encourage tuning of silsesquioxane compounds structure and probably process itself if implementation of these novel organosilicon compounds as surface treatment agents is sought for special applications, e.g., high performance coating systems. Full article

(This article belongs to the Special Issue Feature Collection in Advanced Composites Section)

► Show Figures

Figure 1

9 pages, 3039 KiB

Open AccessCommunication

Hierarchical Interfaces as Fracture Propagation Traps in Natural Layered Composites

by Hanoch Daniel Wagner

Materials 2021, 14(22), 6855; https://doi.org/10.3390/ma14226855 - 13 Nov 2021

Cited by 5 | Viewed by 1599

Abstract

Compared with their monolithic version, layered structures are known to be beneficial in the design of materials, especially ceramics, providing enhanced fracture toughness, mechanical strength, and overall reliability. This was proposed in recent decades and extensively studied in the engineering literature. The source [...] Read more.

Compared with their monolithic version, layered structures are known to be beneficial in the design of materials, especially ceramics, providing enhanced fracture toughness, mechanical strength, and overall reliability. This was proposed in recent decades and extensively studied in the engineering literature. The source of the property enhancement is the ability of layered structures to deflect and often arrest propagating cracks along internal interfaces between layers. Similar crack-stopping abilities are found in nature for a broad range of fibrillary layered biological structures. Such abilities are largely governed by complex architectural design solutions and geometries, which all appear to involve the presence of various types of internal interfaces at different structural levels. The simultaneous occurrence at several scales of different types of interfaces, designated here as hierarchical interfaces, within judiciously designed layered composite materials, is a powerful approach that constrains cracks to bifurcate and stop. This is concisely described here using selected biological examples, potentially serving as inspiration for alternative designs of engineering composites. Full article

(This article belongs to the Special Issue Feature Collection in Advanced Composites Section)

► Show Figures

Figure 1

21 pages, 3836 KiB

Open AccessFeature PaperArticle

Effect of Nanoparticles Surface Bonding and Aspect Ratio on Mechanical Properties of Highly Cross-Linked Epoxy Nanocomposites: Mesoscopic Simulations

by Maxim D. Malyshev, Daria V. Guseva, Valentina V. Vasilevskaya and Pavel V. Komarov

Materials 2021, 14(21), 6637; https://doi.org/10.3390/ma14216637 - 04 Nov 2021

Cited by 3 | Viewed by 2340

Abstract

The paper aims to study the mechanical properties of epoxy resin filled with clay nanoparticles (NPs), depending on their shapes and content on the surface of a modifying agent capable of forming covalent bonds with a polymer. The cylindrical clay nanoparticles with equal [...] Read more.

The paper aims to study the mechanical properties of epoxy resin filled with clay nanoparticles (NPs), depending on their shapes and content on the surface of a modifying agent capable of forming covalent bonds with a polymer. The cylindrical clay nanoparticles with equal volume and different aspects ratios (disks, barrel, and stick) are addressed. The NPs’ bonding ratio with the polymer (RGC) is determined by the fraction of reactive groups and conversion time and varies from RGC = 0 (non-bonded nanoparticles) to RGC = 0.65 (more than half of the surface groups are linked with the polymer matrix). The performed simulations show the so-called load-bearing chains (LBCs) of chemically cross-linked monomers and modified nanoparticles to determine the mechanical properties of the simulated composites. The introduction of nanoparticles leads to the breaking of such chains, and the chemical cross-linking of NPs with the polymer matrix restores the LBCs and strengthens the composite. At small values of RGC, the largest value of the elastic modulus is found for systems filled with nanoparticles having the smallest surface area, and at high values of RGC, on the contrary, the systems containing disk-shaped particles with the largest surface area have a larger elastic modulus than the others. All calculations are performed within the framework of a mesoscopic model based on accurate mapping of the atomistic structures of the polymer matrix and nanoparticles into coarse-grained representations, which, if necessary, allow reverse data mapping and quantitative assessment of the state of the filled epoxy resin. On the other hand, the obtained data can be used to design the functional materials with specified mechanical properties based on other practically significant polymer matrices and nanofillers. Full article

(This article belongs to the Special Issue Feature Collection in Advanced Composites Section)

► Show Figures

Figure 1

18 pages, 5367 KiB

Open AccessArticle

Electrospinning Processing Techniques for the Manufacturing of Composite Dielectric Elastomer Fibers

by Mirella Ramirez, Louis Vaught, Chiu Law, Jacob L. Meyer and Rani Elhajjar

Materials 2021, 14(21), 6288; https://doi.org/10.3390/ma14216288 - 22 Oct 2021

Cited by 3 | Viewed by 1939

Abstract

Dielectric elastomers (DE) are novel composite architectures capable of large actuation strains and the ability to be formed into a variety of actuator configurations. However, the high voltage requirement of DE actuators limits their applications for a variety of applications. Fiber actuators composed [...] Read more.

Dielectric elastomers (DE) are novel composite architectures capable of large actuation strains and the ability to be formed into a variety of actuator configurations. However, the high voltage requirement of DE actuators limits their applications for a variety of applications. Fiber actuators composed of DE fibers are particularly attractive as they can be formed into artificial muscle architectures. The interest in manufacturing micro or nanoscale DE fibers is increasing due to the possible applications in tissue engineering, filtration, drug delivery, catalysis, protective textiles, and sensors. Drawing, self-assembly, template-direct synthesis, and electrospinning processing have been explored to manufacture these fibers. Electrospinning has been proposed because of its ability to produce sub-mm diameter size fibers. In this paper, we investigate the impact of electrospinning parameters on the production of composite dielectric elastomer fibers. In an electrospinning setup, an electrostatic field is applied to a viscous polymer solution at an electrode’s tip. The polymer composite with carbon black and carbon nanotubes is expelled and accelerated towards a collector. Factors that are considered in this study include polymer concentration, solution viscosity, flow rate, electric field intensity, and the distance to the collector. Full article

(This article belongs to the Special Issue Feature Collection in Advanced Composites Section)

► Show Figures

Figure 1

16 pages, 4251 KiB

Open AccessArticle

In Situ Grafted Composite Nanoparticles-Reinforced Polyurethane Elastomer Composites with Excellent Continuous Anti-Impact Performance

by Feng Qi, Zhuoyu Zheng, Zehui Xiang, Biao Zhang, Fugang Qi, Nie Zhao and Xiaoping Ouyang

Materials 2021, 14(20), 6195; https://doi.org/10.3390/ma14206195 - 19 Oct 2021

Viewed by 2019

Abstract

Polyurethane elastomer (PUE) has attracted much attention in impact energy absorption due to its impressive toughness and easy processability. However, the lack of continuous impact resistance limits its wider application. Here, an amino-siloxane (APTES) grafted WS₂-coated MWCNTs (A-WS₂@MWCNTs) filler [...] Read more.

Polyurethane elastomer (PUE) has attracted much attention in impact energy absorption due to its impressive toughness and easy processability. However, the lack of continuous impact resistance limits its wider application. Here, an amino-siloxane (APTES) grafted WS₂-coated MWCNTs (A-WS₂@MWCNTs) filler was synthesized, and A-WS₂@MWCNTs/PUE was prepared by using the filler. Mechanical tests and impact damage characterization of pure PUE and composite PUE were carried out systematically. Compared with pure PUE, the static compressive strength and dynamic yield stress of A-WS₂@MWCNTs/PUE are increased by 144.2% and 331.7%, respectively. A-WS₂@MWCNTs/PUE remains intact after 10 consecutive impacts, while the pure PUE appears serious damage after only a one-time impact. The improvement of mechanical properties of A-WS₂@MWCNTs/PUE lies in the interfacial interaction and synergy of composite fillers. Microscopic morphology observation and damage analysis show that the composite nanofiller has suitable interfacial compatibility with the PUE matrix and can inhibit crack growth and expansion. Therefore, this experiment provides an experimental and theoretical basis for the preparation of PUE with excellent impact resistance, which will help PUE to be more widely used in the protection field. Full article

(This article belongs to the Special Issue Feature Collection in Advanced Composites Section)

► Show Figures

Graphical abstract

Review

Jump to: Research

26 pages, 2627 KiB

Open AccessReview

Polymer Geogrids: A Review of Material, Design and Structure Relationships

by Mohammad Al-Barqawi, Rawan Aqel, Mark Wayne, Hani Titi and Rani Elhajjar

Materials 2021, 14(16), 4745; https://doi.org/10.3390/ma14164745 - 22 Aug 2021

Cited by 18 | Viewed by 6569

Abstract

Geogrids are a class of geosynthetic materials made of polymer materials with widespread transportation, infrastructure, and structural applications. Geogrids are now routinely used in soil stabilization applications ranging from reinforcing walls to soil reinforcement below grade or embankments with increased potential for remote-sensing [...] Read more.

Geogrids are a class of geosynthetic materials made of polymer materials with widespread transportation, infrastructure, and structural applications. Geogrids are now routinely used in soil stabilization applications ranging from reinforcing walls to soil reinforcement below grade or embankments with increased potential for remote-sensing applications. Developments in manufacturing procedures have allowed new geogrid designs to be fabricated in various forms of uniaxial, biaxial, and triaxial configurations. The design flexibility allows deployments based on the load-carrying capacity desired, where biaxial geogrids may be incorporated when loads are applied in both the principal directions. On the other hand, uniaxial geogrids provide higher strength in one direction and are used for mechanically stabilized earth walls. More recently, triaxial geogrids that offer a more quasi-isotropic load capacity in multiple directions have been proposed for base course reinforcement. The variety of structures, polymers, and the geometry of the geogrid materials provide engineers and designers many options for new applications. Still, they also create complexity in terms of selection, characterization, and long-term durability. In this review, advances and current understanding of geogrid materials and their applications to date are presented. A critical analysis of the various geogrid systems, their physical and chemical characteristics are presented with an eye on how these properties impact the short- and long-term properties. The review investigates the approaches to mechanical behavior characterization and how computational methods have been more recently applied to advance our understanding of how these materials perform in the field. Finally, recent applications are presented for remote sensing sub-grade conditions and incorporation of geogrids in composite materials. Full article

(This article belongs to the Special Issue Feature Collection in Advanced Composites Section)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Feature Collection in Advanced Composites Section

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (9 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI