Reinforced Polymer Composites Research Articles

Thermo-Mechanical Properties and Applications of Glass Fiber Reinforced Polymer Composites

Thermo-Mechanical Properties and Applications of Glass Fiber Reinforced Polymer Composites

Extraction and Characterization of Natural CASCABELA Thevetia Bast Fibers: A Potential Candidate as Reinforcement in Epoxy Composites

ABSTRACT The aim of this study is to explore the potential of CASCABELA thevetia (CT) bast fibers as reinforcement in polymer composites. For this purpose, the extracted fibers were chemically treated with various chemicals such as sodium hydroxide, potassium permanganate, sodium chlorite, and benzoyl chloride. After surface modifications, its physical and mechanical properties, chemical composition, and structure were studied. The X-ray diffraction (XRD) results revealed an increase in crystallinity index of the fibers as compared to untreated fibers with benzoyl chloride treated fibers showing the optimum result which agrees with the results obtained in the mechanical tests. Composites were fabricated by taking various wt.% of benzoyl chloride treated CT fibers in an epoxy matrix (i.e. 5, 10, 15, 20, 25, and 30 wt%) and their mechanical and wettability tests were carried out. It was observed that composites with 20 wt% of fiber loading show the highest mechanical properties (52.79 MPa tensile strength, 2.45 GPa Young’s modulus, 71.72 MPa flexural strength). All the fabricated composites showed contact angle less than 90°, which is associated with composite hydrophilic surface properties. These composites can be utilized in lightweight structural material and in automobile industries owing to its better properties.

Effect of Graphene Nanoplatelets on Flexural Behavior of Glass Fiber Reinforced Polymer Composites Subjected to Different Temperatures

Glass Fiber Reinforced Polymer (GFRP) Composite are increasing rapidly in Aerospace Industry, Civil and Wind energy sectors, where they can frequently be exposed to different temperature conditions. As the constituent polymer matrix is highly affected by temperature, extreme temperature conditions are critical for GFRP composite structural design. Researchers have recently found nanofillers such as graphene and carbon nanotubes with excellent multifunctional mechanical properties. Graphene Nanoplatelets (GnP) consist of several layers of graphene. GnP is considering an attractive nanofillers as it has improved polymer matrix properties. In this study, the weight percentage of GnP added in GnP-GFRP laminate is 0.25% and 0.5%.GFRP and GnP-GFRP laminates are fabricated by using the hand lay-up method, and the specimens are subjected to a three-point bending test in a thermal chamber with varying the temperature, i.e., 30°C, 50°C, 75°C, and 100°C. This paper investigates the effect of graphene nanoplatelets on the flexural behavior of glass fiber-reinforced polymer composites subjected to different temperatures. Flexural strength and modulus are evaluated, and the appropriate conclusions are determined. GFRP with 0.25% GnP shows higher strength than the neat and 0.5% GnP-GFRP. Here, it has also been shown that flexural strength and modulus decrease significantly with increasing temperature.

Numerical investigation of intrinsic competing damage mechanisms in unidirectional fiber reinforced polymer composites under compression

A three-dimensional repeating unit cell (3D-RUC) framework is used to analyze the effect of competing damage mechanisms—fiber failure, matrix plasticity/cracking, and fiber-matrix debonding—on the composite’s compressive behavior. Numerous parametric studies are carried out to investigate the impact of fiber volume fraction, fiber misalignment, and interfacial properties (such as strength, fracture energies, and friction) on compressive behavior. The results show that the compressive strength and kink band characteristics are integrally dependent on the fiber volume fraction, fiber misalignment, interfacial shear strength, interfacial friction, and matrix cracking, highlighting the need to accurately characterize the constituent’s mechanical properties and geometrical features.

Preparation and characterization of short date palm mat (DPM) fiber reinforced polystyrene composites: Effect of gamma radiation

The utilization of natural fiber reinforced polymer composites is growing fast in numerous sectors. In this study, the effect of the addition of short date palm mat (DPM) fibers in polystyrene matrix on the physico-mechanical and thermal properties were studied. Short DPM fiber reinforced polystyrene composites were produced by compression moulding process and the fiber content was 5, 10, 15, 20 and 25 wt%. Physico-mechanical and thermal properties were examined. Scanning electron microscopy (SEM) and Fourier-transform infrared (FT-IR) analysis of the composites were also done. The findings from the investigates exposed that the composites with 10 % fiber content showed improved mechanical and thermal characteristics as compared to other composites. The morphological analysis also supported the results where good interfacial bonding among fiber and polystyrene matrix was found for the composites with 10 % fiber content. The optimized (10 % fiber content) composites were exposed to gamma radiation (2.5–7.5 kGy) and the best result was found at 5.0 kGy radiation dose. Degradation of gamma irradiated composites was conducted in four different media such as water, acid, base, and brine.

Constructing quasi-vertical fiber bridging behaviors of aramid pulp at interlayer of laminated basalt fiber reinforced polymer composites to improve flexural performances

Basalt Fiber Reinforced Polymer (BFRP) composites have huge potential application respects for some civil fields due to enough strength/modulus to weight and low cost by replacing carbon fiber composites. Aiming at the issues in the Resin-Rich Region (RRR) and Interfacial Transition Region (ITR) of fiber reinforced polymer composites, the characteristic Aramid Pulp (AP) fibers with micro-fiber trunk and nano-fiber branches were manufactured into multiple non-woven ultra-thin interleaving at the interlayers of BFRP composites via compression molding to reinforce the flexural strengths and elastic moduli. AP fibers were introduced into RRR to form interleaving at the interlayer, the brittle epoxy adhesive layer was improved and enabled to avoid cracking under a low external load. Free fiber branches of AP were also embedded into BF layer to construct quasi-vertical fiber bridging behaviors in ITR, stronger mechanical interlocking was created to prevent crack propagation along the bonding interface of BF/epoxy. Three-point bending testing results showed the interleaving film with 4 g/m2 AP exhibited the best effect among various areal densities and yielded average 315.75 MPa in flexural strength and 21.38 GPa in elastic modulus, having a 63.4% increment and a 47.1% increment respectively compared with the bases. Overall, the simple and low-cost AP interleaving is confirmed as an effective method in improving interlayer structure and flexural performance of BFRP composites, which may be considered to manufacture high-performance laminated fiber reinforced polymer composites in civil aviation industry.

Mechanical properties and tribological performance of polyoxymethylene/short cellulose fiber composites

Natural fibers are promising bio-based materials to use as reinforcements in polymer composites as often more affordable and accessible alternatives to fossil-based fibers, especially because of their superior sustainability. Polyoxymethylene (POM) is a widely used engineering thermoplastic, which has a melting temperature suitable for processing with natural fibers. In this study, such composites consisting of POM and regenerated cellulose fibers have been developed and studied in terms of their mechanical, thermal, tribological and structural properties. Tensile and flexural moduli increased with incorporation of 30 wt% fibers up to 89% and 79% respectively, crystallinity increased as well by a maximum of approx. 11% at 30% fiber content. Furthermore, the specific wear rate was improved for the composite with 10 wt% fibers, showing a decrease of roughly 80%. This study investigates the processing parameters and tribo-mechanical performance of POM-based natural fiber composites as an important route towards future sustainable polymer composites in load bearing applications.

Recent Progress on Moisture Absorption Aging of Plant Fiber Reinforced Polymer Composites.

Plant fiber reinforced polymer matrix composites have attracted much attention in many industries due to their abundant resources, low cost, biodegradability, and lightweight properties. Compared with synthetic fibers, various plant fibers are easy to obtain and have different characteristics, making them a substitute for synthetic fiber composite materials. However, the aging phenomenon of composite materials has been a key issue that hinders development. In natural environments, moisture absorption performance leads to serious degradation of the mechanical properties of composite materials, which delays the use of composite materials in humid environments. Therefore, the effects of moisture absorption performance of plant fiber composite materials on their mechanical properties have been summarized in this article, as well as various treatment methods to reduce the water absorption of composite materials.

Effect of strain rate on glass fiber reinforced polymer composite using split hopkinson pressure bar

The aim of this study is to examine the stress–strain behavior of Glass Fibre Reinforced Polymer (GFRP) composite with three different orientations, namely [0°/90°]s, [±45]s, [0°/+45°/−45°/90°]T. To achieve this, the GFRP was simulated using the Split Hopkinson Bar (SHPB) setup in ABAQUS/CAE. The striker bar was used at three different velocities (9.7 m s−1, 12.7 m s−1, and 14.3 m s−1) to produce strain rates ranging from 1000 s−1 to 2000 s−1. The dynamic response of the GFRP composite was studied by considering its stress–strain behavior. The effect of strain rate on the elastic modulus and energy absorption capacity of GFRP laminates was analyzed through complete stress versus strain curves. The results showed that the elastic modulus and energy absorption capacity of GFRP laminates were sensitive to strain rates, with an increase in strain rate leading to an increase in the elastic modulus and energy absorption capacity.

Experimental investigation of 3D printed infill structures for crash absorbing applications

In recent years additive manufacturing technologies have rapidly evolved and are now an effective tool adopted for final components production. 3D printing techniques allow to realize complex geometries that are difficult if not impossible to fabricate by means of conventional production methods. This peculiarity can be exploited to design and manufacture infill structures that can be used in various engineering applications. Combining lightweight 3D printed infill structures with conventional laminate carbon-epoxy composites can be an efficient way to realize light and stiff components that find their optimal use in crash absorbing applications. Plain polymers and fiber reinforced polymers composites represent an interesting solution for additive manufacturing, offering light weight and ductility of the polymeric matrix with the possible enhancement of mechanical properties with the addition of fibers. This work focuses on the study of commercially available 3D printed infill structures via compression tests on cubic samples, deepening understanding about different densities and different strain rates effects on material’s behavior.

Optimization of the Alkali-Silane Treatment of Agave lechuguilla Fibers (Ixtle) for Potential Reinforcement in Polymeric Composites

Reinforced polymeric composites with natural fibers have garnered significant interest in recent years due to the need for biomass utilization and the requirements of various industries, such as automotive and construction. Among these natural fibers, Agave lechuguilla fiber, commonly known as ixtle (FIx) or Tampico fiber, exhibits important characteristics such as length, high strength, and durability. However, there is limited literature on its conditioning, functionalization, and utilization as a reinforcing material in polymeric composites (CP). This study presents the optimization of the alkali-silane treatment of FIx, identifying the most suitable reaction conditions to enhance their thermal stability, tensile strength, and silane coupling agent (ACSi) grafting on the fiber surface. The chemical treatment with ACSi proved highly effective, resulting in a significant grafting content, which was confirmed through FTIR and SEM–EDS analyses. The high level of functionalization did not compromise the mechanical performance of the fibers, suggesting that functionalized FIx holds great potential as a reinforcing material in CP. These findings open new paths for the sustainable use of Agave lechuguilla fibers, contributing to the development of environmentally friendly and high-performance polymeric composites in various industrial applications.

Multi-attribute optimization of drilling CFRP/Ti-6Al-4V alloy hybrid stacks using VIKOR

Drilling carbon reinforced polymer composites (carbon fiber-reinforced polymers, CFRP) and the hole quality produced are highly critical and significantly influence the performance and reliability of structures used in aircraft components. When CFRP composites are stacked together with titanium alloy, the damage caused by the machining operation is incalculable due to the burr and chip evacuation of metallic phases. In this article, efforts were made toward the identification of optimal machining conditions in drilling CFRP/titanium hybrid stacks. Experimental investigations on dry drilling of CFRP/titanium stacks were conducted with the aid of tungsten carbide drills. This research article discusses an improved compromise ranking method named VIKOR (VIseKriterijumska Optimizacija I Kompromisno Resenje) to determine the optimal machining parameters in drilling of CFRP/titanium stacks to produce high-quality holes. Attributes measured from experimental trials are: delamination factor of CFRP, burr height of titanium alloy, thrust force, torque, surface roughness, roundness and hole diameter of CFRP and titanium alloy. Experimental trial 13 with a combination of speed of 30 m/min, feed of 0.025 mm/rev was chosen as an ideal machining parameter in drilling CFRP/Ti-6Al-4V stacks without any trade-off. Confirmation tests convey that the results agree well with optimal parameters and the decision making in drilling such multimaterial stacks is highly consistent and judicious. In regard to the optimal parameters determined, investigations on tool life were performed and a tool life of 20 min for 0.10 mm flank wear land was observed.

Modifikasi Serat Kenaf (Hibiscus cannabinus L.) Menggunakan Anhidrida Propionat

Kenaf is a local crop that has great potential as a polymer composite reinforcement. However, the main weakness in strengthening composites using kenaf fiber is its hydrophilic or water-absorbing properties. To improve composite properties, surface modification of kenaf fiber is needed to enhance the structure and chemical properties of kenaf fiber. This study aims to explore the potential of chemical modification of kenaf fiber for use in composites. Chemical modification treatment of kenaf fibers was intended to improve the hydrophobicity that the compatibility between the fiber and matrix bonds are enhanced. In this study, chemical modification of kenaf fiber was performed using propionic anhydride. The modification process was done through a three-variation of retention time; 100, 200, 300 minutes at 100 °C. This research also compared the kenaf fiber properties with and without the modification process, including the analysis of the weight percent gain and surface morphological structure. The results showed that the optimal weight gain and morphological structure was at a retention time of 200 minutes.

Characterization of material degradation mechanism of carbon fiber reinforced epoxy resin composites under ultraviolet radiation and salt‐fog synergistic environment

AbstractThe influence of harsh environment conditions on carbon fiber reinforced polymer composites (CFRP) restricts their popularization and usage in outdoor marine applications. Although many studies have been conducted on the service characteristics of CFRP under different conditions, the effect of ultraviolet (UV) radiation and salt‐fog synergistic aging has not been researched in detail. The primary focus of this work is to understand the aging degradation mechanism and mechanical response of CFRP in this harsh environment. The test samples were exposed to UV and salt‐fog synergistic environment. Then the physicochemical properties, dynamic/static mechanical behavior of all samples were characterized. The results show that the CFRP exposed to UV and salt‐fog environment represent noticeable synergistic aging effects. The matrix plasticization and particle washing caused by UV radiation and water condensation will intensify the erosion effect of chloride ions, thus leading to significant deterioration of the fiber‐matrix interface and interlaminar bonding. After aging, the deformation resistance of the material reduces, the molecular chain movement intensifies, the cross‐linking density of the resin matrix decreases, and the maximum decline of glass transition temperature reaches 32.36%. Compared with the tensile performance, the degradation of interlaminar shear performance is more serious, of which the interlaminar shear performance are mainly determined by the matrix and interlaminar properties. Besides, for the aged samples, more serious irreversible deformation appears during the loading process.Highlights The CFRP shows noticeable synergistic aging effects under UV and salt‐fog aging, which the matrix plasticization and particle washing caused by ultraviolet radiation and water condensation will intensify the erosion effect of chloride ions. The decrease of the cross‐linking density of CFRP materials is the primary cause for the deformation resistance reduction and properties degradation. Compared with the tensile performance, the degradation of interlaminar shear performance is more serious.

Self-Healing Performance of Carbon Fibre Reinforced Composite Containing Microcapsules under Tensile Load

Self-healing is fascinating research due to its distinctiveness in automatically mending the damages. A great deal of work has been done using the self-healing concept in polymers. However, there is limited research on fibre reinforced polymer composites. Adding microcapsules during fabrication of the composites is one of the methods which is capable of carrying out the healing of damage autonomously. This research work takes into account the preparation of fibre reinforced composites with incorporation of two types of microcapsules i.e., healing agent carriers and curing agent carriers in the course of fabrication to mend the damages generated. The work experiments the impact of inclusion of microcapsules on the tensile properties of host composite laminate. Results of tensile tests indicate that a significant amount of tensile strength of the specimens was restored by healing and curing agents present in microcapsules. The healing efficiency was observed as 61.3%. It has also been noted that, the presence of these capsules does not significantly alter the original performance of the laminate as the effect of capsule inclusion on properties of the laminate is negligible.

Material properties of spray‐dried cellulose nanocrystal reinforced homopolymer polypropylene composites

AbstractSpray‐dried cellulose nanocrystal (SDCNC) particles have attracted intense interest as reinforcements in polymer composites because of their unique physical and mechanical properties. This work aims to develop homopolymer polypropylene (HPP) composites with different loading levels of SDCNC particles (5, 10, 15, and 30 wt%) to understand their impact on composite mechanical, morphological, and thermal properties. The SDCNC‐reinforced HPP composites were manufactured using a C.W. Brabender bowl internal mixer with a masterbatch concept and an injection molding process. The mechanical, morphological, and thermal properties of the composites were investigated. Compared to pure HPP, the tensile, and flexural modulus of elasticity (MOE) of composites with 30 wt% SDCNC significantly increased by up to 67% and 49%. The impact strength of the composites with the absence of a compatibilizer significantly increased by up to 19%, which was attributed to the mechanical interlocking network established between SDCNC particles and HPP. Additionally, increasing SDCNC loading in the composites led to higher crystallization peak temperatures and increased the degree of crystallinity (especially at 30 wt% SDCNC content), indicating that the SDCNC particles can act as heterogeneous nucleating agents during the crystallization process. The thermal stability of the composite was slightly improved upon SDCNC introduction.Highlights With the incorporation of spray‐dried cellulose nanocrystal (SDCNC), the tensile modulus of elasticity (MOE), flexural MOE, and impact strength of filled homopolymer polypropylene (HPP) composites were significantly improved by up to 67%, 49%, and 19%, respectively. Mechanical interlocking network established between SDCNC and HPP contributed to the enhanced the impact strength. SDCNC particles can act as heterogeneous nucleating agents to promote the crystallization process of HPP. SDCNC particles slightly enhanced the thermal stability of HPP composite.

A novel study of biological and structural analysis on Cissus quadrangularis fiber-reinforced CaO particulates epoxy composite for biomedical application

Natural fibers derived from renewable, environmentally sustainable sources are being considered for use as reinforcements in polymer composites. The current study focuses on the fabrication of composite materials using fiber extracted from the Cissus quadrangularis (CQ) natural plant as reinforcement, an epoxy polymer as a matrix, and calcium oxide (CaO) nanoparticles as filler material, with the weight ratio of Cissus quadrangularis fiber (CQF) and CaO filler materials are varied to quantify the biological and structural effects of CQF composite. X-ray diffraction (XRD) results demonstrate a 58% amorphous zone in this composite, while Fourier transforms infrared spectroscopy (FTIR) examination revealed the hydrophobic nature, chemical bonding, and cellulose content. Because of the increased amount of chopped CQF loading in this composite, the mechanical qualities result in an average of 23% better tensile strength. Scanning electron microscopic (SEM) analysis was used to analyze the failure analysis for fiber interaction with matrix, filler, and fiber pullouts under mechanical stress. The antibacterial research revealed that this CQF composite exhibits bacterial inhibitory activity suitable for biomedical applications.

Correlating microstructure-property relationships in carbon fiber-expanded graphite hybrid composites for synergistic improvements in thermal and mechanical properties

Thermally conductive and structurally reinforcing polymer composites are in high demand for applications such as electric vehicles, rapid prototyping, and thermal interface materials. Including a single geometry (platelet or rod) filler is a common strategy to improve the performance of polymers. However, the thermal and mechanical properties follow an inverse dependence and often require high filler loadings that compromise the overall properties. Hybridization of filler geometries has effectively improved the thermal conductive network while retaining mechanical performance. The focus of this work is to understand the effect of microstructure and interactions of hybrid fillers in high strength thermally conductive composites. For this study, expanded graphite, and carbon fibers (CFs) were used as the hybrid filler system to improve the thermal conductivity and mechanical properties of polyamide-based thermoplastic composites. The detailed microstructural study revealed that at a lower normalized weight ratio of CFs, the fibers bridge the expanded graphite particles to create a filler-filler network which leads to synergistic effect on both the tensile strength (by 29%) and thermal conductivity (by 290%) compared to a single-filler expanded graphite-based system. Above a critical mass fraction of CF, the planar graphitic orientation led to a loss in thermal conductivity which is attributed to reduced exfoliation and packing density of fillers.

Fractal Approach to Dielectric Properties of Single Walled Carbon Nanotubes Reinforced Polymer Composites

In this paper, the internal structure and dielectric properties of unsaturated polyester resin-based neat and single-walled carbon nanotube reinforced composites were comprehensively evaluated with the fractal analysis using the Fast Fourier Transform (FFT). The greyscale images, bitmap (BMP) images and 3D tomographic images were obtained by converting the scanning electron microscope images of the materials. It was observed that the distributions of components in the resin for both materials are irregular and their surfaces exhibit anisotropic behaviors. The surface coating rate (SCR) and fractal dimensionality (FD) of the materials were also calculated using the power spectrum. It has been observed that the fractal dimensionality of the composites can be changed by the doping process and the fractalization of the nanotube doped sample increases compared to the pure material due to nanotube agglomeration, spatial distribution and the orientation. The increase in fractalization as a result of this agglomeration and orientation in carbon nanotubes explains the high dielectric constant values observed at low frequencies by increasing the number and size of carbon nanotubes clusters that act as micro capacitors in certain regions of the matrix. It has been reported that the calculations for the surface coverage ratios for both samples also support these results.

Design of Core-Shell Polylactic Acid (PLA) electrospun nanofibers as potential healing carriers

This study intends to maximize the encapsulation rate of healing carriers in core-shell nanofibers to augment the healing capabilities of the nanofibers in laminated composites synthesized via coaxial electrospinning. Core-shell nanofibers fabricated at a high core flow rate yielded defective fibers due to an insufficiency of shell solution to encapsulate the core solution being ejected from the syringe. Hence, a core-to-shell flow rate of 6.7:1 was identified to be optimal with an encapsulation content of over 50% without affecting its morphology. Thermogravimetric and spectral analysis of the healing NF showed the degradation of each constituent and their respective peaks, confirming the presence of the core solution without any chemical reaction with the PLA shell wall. Release of healing agents was observed under SEM, and the self-healing traits of the nanofibers were studied by subjecting them to repeated loadings under tension with significant strength retention without failure after four load cycles making these nanofibers highly valuable as a secondary reinforcement in polymer composites due to the nanofibers’ toughening and healing capabilities.