Reinforced Polymer Composites Research Articles

Influence of Fiber Type on Electrical, Thermal and Mechanical Properties of Glass Fiber Reinforced Polymer Composites for Insulation Panel Applications

Influence of Fiber Type on Electrical, Thermal and Mechanical Properties of Glass Fiber Reinforced Polymer Composites for Insulation Panel Applications

Using soft computing to forecast the strength of concrete utilized with sustainable natural fiber reinforced polymer composites

Using soft computing to forecast the strength of concrete utilized with sustainable natural fiber reinforced polymer composites

Enhanced shape memory performance and numerical simulation of knitted‐fabric reinforced polymer composites with weft yarns

AbstractFabric‐reinforced shape memory polymeric composites (SMPC) have shown great potential in the design of intelligent deformation structures. In this work, the weft‐knitted fabric inserted with weft yarns was developed as reinforcement to fabricate the shape memory epoxy polymer (SMEP) composites. The effects of weft yarn, loop density and direction on the shape memory performance of SMPC under different bending radii were experimentally investigated. The results show that the SMPC have good shape fixity ratios and shape recovery ratios of around 98%. As compared with those of SMPCs without inserting weft yarns, the SMPCs with weft yarns have shorter shape recovery time, and the recovery force of SMPCs with weft yarns in the 0° and 90° directions shows an increase of 86.4% and 79.5%, respectively. The recovery force of SMPC improve 3.7 times compared to SMEP. The multiscale models of SMPC were established with basis of the results of micro‐computed tomography scanning of specimens and viscoelastic theory. The surface buckling behaviors of SMEP and SMPC specimens after U‐bending load were discussed. Finally, the deformation of loops and weft yarns of SMPC were analyzed to reveal the shape memory mechanism.Highlights Shape memory polymeric composites (SMPC) with weft yarns has shorter shape recovery time. Recovery force of SMPC with weft yarns was obvious enhanced. Multi‐scale viscoelastic models of SMPC were established. Surface buckling behaviors of SMPC after U‐bending load were revealed.

A comparative analysis of the tribological performance of coir, bamboo and wood filler reinforced polymer composites

Abstract Researchers and academics are increasingly favoring natural fibres for incorporation into polymer composites on account of their ecological compatibility and longevity. The aim of this comparative study is to identify the optimal natural filler by AHP-TOPSIS approach by analyzing the tribological performance of three distinct natural fillers: coir, bamboo, and wood reinforced polymer composite. These filler materials are pre-treated by alkali treatment to increase the interlinking properties between filler and polymer. The outcome of these treatments on the composites’ physical and mechanical properties are investigated. Using a Pin-on-disk (POD) machine under dry, wet, and heated sliding contact conditions, different natural fillers’ effects on polymer wear and friction are examined. The wear rate and coefficient of friction (COF) were quantified as a function of the sliding distance (0–2000 m) under various normal loads (5–40 N). It was observed from the different experimental results that coir filler reinforced composite shows best wear resistance property whereas wood filler reinforced composite shows the least wear resistance composite. Results revealed that lower filler support and low load show better wear resistant property compared to the higher filler support and high load condition. When seen through a microscope, the worn surfaces of the composite material exhibit micro and macro fissures, as well as debonding and plastic deformation. The coir filler-based composite was found to be the best alternative using the AHP-TOPSIS method, with a closeness coefficient of 0.770023.

Applying optical coherence tomography to inline quality monitoring of unidirectional glass-fiber-reinforced thermoplastic tapes

Originally developed for biomedical applications and diagnosis, optical coherence tomography (OCT) has recently been demonstrated to be a powerful non-destructive and non-invasive measurement method for detecting defects in glass-fiber reinforced polymer composites. While previous studies have focused mainly on the use of OCT in the analysis of thermoset composites, we were able to show in offline experiments that OCT can be used to quickly detect typical defects (e.g., dry fiber regions, gaps and fiber breakage) in thermoplastic unidirectional (UD) tapes at high resolution. To investigate the applicability of OCT to inline monitoring, we advanced our previously published approach in two major steps: First, we incorporated the OCT system into an industrial-scale UD-tape production line, and derived optimal settings for inline detection of dry region defects from a comprehensive design of experiments (DoE) to find an optimal balance between accuracy and data size for a stationary tape sample by varying A-scan sampling rate, A-scan averaging and OCT transverse travel velocity. Second, using these optimal settings, we went on to investigate moving tapes over a range of industrially relevant take-off speeds. Microscopy was used for validation in both cases. We developed a fast and robust statistical analysis of B-scans that visualizes the quality of full cross-sections in an interpretable manner for potential use in a real-time setting. Within an industrially relevant production speed range of up to 15 m/min, we are thus now able to investigate 120 mm wide (and potentially wider) UD tapes inline at a transverse resolution of 22 µm, producing only 21 MB of data per measurement.

Constructing coordination-connected flexible-rigid structures for the interfacial enhancement of CF/polyetheretherketone composites

Carbon fiber (CF) reinforced polymer composites have found widespread application due to their exceptional properties, including high specific strength and modulus, thermal stability, and chemical durability. However, since the interface serves as the bridge for load transfer between fiber and resin, the interfacial property directly affects the holistic performance of the composites. Considering the inertness of CF and polyetheretherketone (PEEK), as well as the modulus gap between them, we propose a flexible-rigid sizing agent to enhance the interfacial interaction. The sizing layers are constructed by the transition layer of polyetherimide (PEI) and the hybrid nanoparticles consisting of rare-earth coordination bonded flexible aramid nanofiber and rigid nano-TiO2. Calculated by density functional theory (DFT), the electron density difference (EDD) result displays the transfer of electrons between aramid nanofiber and nano-TiO2 acted by rare-earth element. This treatment with flexible-rigid sizing agent significantly improves the surface activity, roughness, and wettability of CF. Meanwhile, the flexural strength and interlaminate shear strength (ILSS) of as-prepared CF/PEEK composites are 91.4% (810.2 MPa) and 58.2% (82.6 MPa) higher than those of unmodified CF/PEEK composites. This work presents a robust and promising approach for fabricating high-performance CF/PEEK composites.

Characterisation of alkali-treated novel cellulosic fibres derived from Dombeya Buettneri plant as a potential reinforcement for polymer composites

ABSTRACT The present study evaluates the influence of alkali treatment using 2, 4, and 8 wt.% sodium hydroxide concentration solutions on novel cellulosic fibres manually extracted from the bark of dombeya buettneri plant (DBF). Alkali-treated fibres were characterised through physical and mechanical properties determination, Fourier transform infrared spectroscopy, X-ray diffraction, quantitative chemical analysis, thermogravimetric analysis, and scanning electron microscopy. Quantitative chemical analysis revealed a significant increment in cellulose content, reaching 67 ± 1.7% in DBF treated with 4 wt.% NaOH solution, accompanied by substantial reductions in lignin and hemicelluloses as confirmed by FTIR spectroscopy. XRD analysis showed an improved crystallinity index of 80% and crystallite size of 2.64 nm for 4 wt.% alkali-treated DBF. Additionally, 4 wt.% alkali-treated fibres yielded peak values of breaking force (40 N) and breaking tenacity (181 cN/Tex). SEM analysis confirmed enhanced surface roughness post-treatment, an indication of enhanced fibre/matrix interlocking during composite fabrication, whereas TGA analysis reported improved thermal stability post-treatment. EDX analysis confirmed that the C/O ratio is proportional to alkali solution concentration, indicating effective removal of non-cellulosic contents. In conclusion, treating DBF with 4 wt.% NaOH concentration improves their physical, mechanical, and chemical properties, suggesting their potential for polymer composite applications.

Comparative study of oil palm and nettle fibers reinforced chemically functionalized high‐density polyethylene composites

AbstractThe demand of natural fiber reinforced composites has grown enormously in polymer industries owing to their renewability and sustainability and maintaining their performance and properties. In this investigation, two natural fibers have been considered as a reinforcer to develop chemically functionalized high‐density polyethylene (CF‐HDPE)‐based composites. The total holocellulose content of ~85% and ~65% for nettle fiber (NTF) and oil palm empty fruit bunch fiber (OPF) make them significant for this study. OPF/CF‐HDPE and NTF/CF‐HDPE composites have been developed and characterized to measure their desirable properties. The structural confirmation suggests reinforcement/matrix adhesion through ester and hydrogen bonds between them. NTF/CF‐HDPE and OPF/CF‐HDPE are thermally stable upto 240°C and 250°C, respectively. A significant increment of ~40% and ~64% in tensile strength were observed in addition of OPF and NTF reinforcer in pristine matrix. A similar observation has been shown in flexural strength with improvement of ~58% and ~83% with OPF and NTF as reinforcer. Among all these composite compositions, the 30/70 NTF/CF‐HDPE composite demonstrated the highest tensile and flexural properties values due to higher holocellulose of NTF. This study demonstrates the potential of OPF and NTF reinforcer to develop natural fiber reinforced polymer composites, which helps respective industries to manufactured tailored made products with desirable properties.Highlights OPF/CF‐HDPE and NTF/CF‐HDPE composites are sustainable and low cost. The composite compositions have been developed by extrusion and injection molding. The composite's mechanical (tensile and flexural) properties have been demonstrated. SEM and FTIR characterized the composites for the fiber/matrix adhesion. The composite's thermal stability has been affected by fibers and matrix.

Mechanical property enhancement of flax fibers via supercritical fluid treatment

The desire for lightweight, carbon-negative materials has been increasing in recent years, particularly as the transportation sector reduces its global carbon footprint. Natural fibers, such as flax fiber and their composites, offer a compelling combination of properties including low density, high specific strength, and carbon negativity. However, because of the low modulus and high variability in performance, natural fibers can’t compete with glass fibers as structural reinforcements in polymer composites. In this study, flax technical fibers were treated in supercritical CO2 (scCO2), and the effects of this treatment on the morphology and properties of flax fibers are reported. Treatment in scCO2 successfully resulted in higher fiber modulus and strength by 33% and 40%, respectively. Fiber porosity was reduced by 50% and morphological changes to the fibers were observed. Specifically, fiber lumen collapsed during treatment and micro/mesoporosity was reduced by 27%. Treated flax fibers were used to create 30 vol% unidirectional flax-epoxy composites. ScCO2 treatment raised composite modulus and strength by 33% and 25%, respectively. Because of the dependence between technical fiber size and mechanical properties, the relationship between fiber modulus and fiber size were created and applied to the rule-of-mixtures. This relationship were found to be viable representations of the fiber performance within each composite. Overall, the treatment developed in this study has the potential to significantly improve natural fiber properties, enabling their consideration for use in lightweight, semi-structural composites.

A molecular dynamics assisted insight on damping enhancement in carbon fiber reinforced polymer composites with oriented multilayer graphene oxide coatings

A molecular dynamics assisted insight on damping enhancement in carbon fiber reinforced polymer composites with oriented multilayer graphene oxide coatings

Sustainable repurpose of end-of-life fiber reinforced polymer composites: A new circular pedestrian bridge concept

In response to global challenges in resource supply, many industries are adopting the principles of the Circular Economy (CE) to improve their resource acquisition strategies. This paper introduces an innovative approach to address the environmental impact of waste Glass Fiber Reinforced-Polymer (GFRP) pipes and panels by repurposing them to manufacture structural components for new bicycle and pedestrian bridges. The study covers the entire process, including conceptualization, analysis, design, and testing of a deck system, with a focus on the manufacturing process for a 7-m-long prototype bridge. The study shows promising results in the concept of a sandwich structure utilizing discarded GFRP pipes and panels, which has the flexibility to account for variabilities in dimensions of incoming products while still meeting mechanical requirements. The LCA analysis shows that the transportation of materials is the governing contributing factor. It was concluded that further development of this concept should be accompanied by a business model that considers the importance of the contributions from the whole value chain.

Construction of porous graphene and network carbon nanotubes to develop high-performance and multifunctional carbon fiber composites

Structurally and functionally integrated carbon fiber reinforced polymer composites (CP) are indispensable in electronic devices, where the combination of brilliant mechanical properties, electromagnetic shielding properties and thermal management capabilities are required. Designing and optimizing the interface structure is an effective solution to the above problems. In this work, porous graphene and network carbon nanotubes were successfully integrated into CP. Graphene and carbon nanotubes form a crosslinked structure in which graphene improve the fiber/matrix interfacial bonding and carbon nanotubes enhance the matrix cohesion. Due to their synergistic enhancement, the tensile strength (183.00 ± 5.66 MPa) of graphene and carbon nanotubes reinforced CP (CG-CP) is increased by 65.85 % and the wear rate (1.19 × 10–13 ± 0.05 × 10−13 m3(N·m)−1) is reduced by 74.52 %. Further, the crosslinked structure of graphene and carbon nanotubes creates a high-conductivity and heat-conductive transmission channel, enabling CG-CP to achieve an electromagnetic interference shielding efficiency of up to 48.94 dB in the X-band and 52.62 dB in the Ku-band at a thickness of 0.3 mm, and a 20.98 % improvement of thermal conductivity (0.767 ± 0.002 W(m·K)−1), which simultaneously achieves excellent electromagnetic shielding performance and thermal management capability. The high-performance and multifunctional CG-CP offers a broad prospect regarding the application of advanced electronic devices.

Eco‐Friendly Chemical Modification of Agave Americana Fibers for Biocomposite Properties Enhancement

AbstractChemical treatments are used to remove hydrophilic OH groups and surface particles from the fiber surface for increasing aspect ratio of fibers and subsequently, mechanical properties. In this paper, the effect of two eco‐friendly chemical treatments on morphology, chemical structure, and thermal stability of Agave Americana fibers (AAFs) is investigated. The first chemical treatment of AAF is based on citric acid (C6H8O7) to substitute OH groups contained in AAF by ester groups, while the second one involves sodium bicarbonate (NaHCO3) to remove the lignin and hemicellulose components with the aim to promote good fiber‐matrix adhesion. Attenuated total reflectance‐Fourier transform infrared spectroscopy (ATR‐FTIR) data shows that both treatments are efficient to remove hemicelluloses and a part of lignin contained in AAF resulting in a rough and clean fiber surface. Thermal stability of AAF has clearly increased by NaHCO3 treatment compared to untreated one, unlike C6H8O7, which reduces this property. The study highlights the possibility of substituting conventional polluting chemical treatments with environmentally friendly ones to modify the surface of plant fibers for polymer composites reinforcement.

Carbon fibre detection in polymer composites reinforced by chopped carbon fibres through digital image processing and machine learning

Mechanical and thermodynamical properties and thus machinability of carbon fibre reinforced polymer composites significantly depend on the fibre orientation relative to the load direction. However, the orientations of the fibre groups in polymer composites reinforced by chopped carbon fibres are stochastic; therefore, the properties and machinability of such composites are challenging to plan, predict and optimise. We developed four different and novel approaches for fibre detection in polymer composites reinforced by chopped carbon fibres: (i) detecting the fibres through naked eye supported manual drawing, (ii) digital image processing of optical images, (iii) machine learning-based fibre detection, and (iv) rectangle fitting on the outputs of the automated processes using the Chaudhuri and Samal method. The applicability of the novel approaches was tested through optically captured images of polymer composites reinforced by chopped carbon fibres. The developed methods are each capable of detecting fibre groups at the top and bottom of the composite plate with certain limitations. The rectangle fitting approaches performed the best from the point of view of correctly identifying of fibre groups, followed by the machine learning-based and the conventional digital image processed, respectively. As a result of this study, the machining process planning and condition monitoring of polymer composites reinforced by chopped carbon fibres is more deeply supported.

Influence of Montmorillonite Organoclay Fillers on Hygrothermal Response of Pultruded E-Glass/Vinylester Composites.

Pultruded fiber reinforced polymer composites used in civil, power, and offshore/marine applications use fillers as resin extenders and for process efficiency. Although the primary use of fillers is in the form of an extender and processing aid, the appropriate selection of filler can result in enhancing mechanical performance characteristics, durability, and multifunctionality. This is of special interest in structural and high voltage applications where the previous use of specific fillers has been at levels that are too low to provide these enhancements. This study investigates the use of montmorillonite organoclay fillers of three different particle sizes as substitutes for conventional CaCO3 fillers with the intent of enhancing mechanical performance and hygrothermal durability. The study investigates moisture uptake and kinetics and reveals that uptake is well described by a two-stage process that incorporates both a diffusion dominated initial phase and a second slower phase representing relaxation and deterioration. The incorporation of the organoclay particles substantially decreases uptake levels in comparison to the use of CaCO3 fillers while also enhancing stage I, diffusion, dominated stability, with the use of the 1.5 mm organoclay fillers showing as much as a 41.5% reduction in peak uptake as compared to the CaCO3 fillers at the same 20% loading level (by weight of resin). The mechanical performance was characterized using tension, flexure, and short beam shear tests. The organoclay fillers showed a significant improvement in each, albeit with differences due to particle size. Overall, the best performance after exposure to four different temperatures of immersion in deionized water was shown by the 4.8 mm organoclay filler-based E-glass/vinylester composite system, which was the only one to have less than a 50% deterioration over all characteristics after immersion for a year in deionized water at the highest temperature investigated (70 °C). The fillers not only enhance resistance to uptake but also increase tortuosity in the path, thereby decreasing the overall effect of uptake. The observations demonstrate that the use of the exfoliated organoclay particles with intercalation, which have been previously used in very low amounts, and which are known to be beneficial in relation to enhanced thermal stability, flame retardancy, and decreased flammability, provide enhanced mechanical characteristics, decreased moisture uptake, and increased hygrothermal durability when used at particle loading levels comparable to those of conventional fillers, suggesting that these novel systems could be considered for critical structural applications.

Kenaf/glass fiber‐reinforced polymer composites: Pioneering sustainable materials with enhanced mechanical and tribological properties

AbstractHybrid kenaf/glass fiber reinforced polymer composites have emerged as promising structural materials, garnering significant attention due to their unique blend of natural kenaf fibers and synthetic glass fibers. However, despite their potential, there remains a gap in the comprehensive understanding of their quasi‐static mechanical behavior, creep resistance, and fatigue performance. This paper addresses this gap by presenting recent advancements in studying these key properties of hybrid composites. Studies reveal that the combination of kenaf and glass fibers results in enhanced tensile, flexural, and impact strengths compared to individual fiber composites. Additionally, the hybridization offers improved creep resistance, with the glass fibers reinforcing the polymer matrix against deformation under sustained loads. Furthermore, investigations into fatigue properties demonstrate the resilience of hybrid composites to cyclic loading, contributing to prolonged service life in high‐stress environments. By elucidating the interplay between kenaf and glass fibers, this review underscores the potential of hybrid composites in various structural applications. The synergistic effects between natural and synthetic fibers offer a balance between sustainability, performance, and durability, making hybrid kenaf/glass fiber reinforced polymer composites a compelling choice for industries seeking lightweight, high‐performance materials in which aligns with the sustainable development goals (SDGs) especially on Goal 12.Highlights In composite engineering, combining glass and kenaf fibers could cut production costs, yield high‐performance materials, and promote green technology. Substituting part of the glass fiber with kenaf can enhance the strength‐to‐weight ratio and promote greater biodegradability in current synthetic composites. Quasi‐mechanical properties of hybrid kenaf/glass‐based composites was enhanced by optimal stacking sequences, filler addition, and fiber treatment. Failures due to fatigue and creep can be reduced by hybridizing kenaf/glass fiber composites can prevent in polymer composite due to enhance elastic modulus. Enhanced tribological performance of hybrid kenaf/glass‐based composites due to less damage in microstructure via good interlocking of kenaf and glass in matrix.

Influence of varying matrix/fiber concentration on mechanical properties of bi-directional carbon fiber reinforced polymer composite

The polymer composites comprising bi-directional carbon fabric incorporated in the epoxy matrix have been developed for various advanced applications in the field of automobile and aerospace sectors. The distinct advantages of using epoxy material with hardener are good adhesion, high tensile, compression and bending strengths, good corrosion, and heat resistance properties. Using carbon fiber enhances the stiffness, reduces the weight, and improves the chemical resistance apart from possessing high thermal conductivity and low coefficient of thermal expansion. Considering all the above aspects, the present work proposes to investigate the mechanical properties of carbon-reinforced epoxy composites with fiber matrix ratios of 40:60, 50:50, and 60:40 by wt% as these particular combinations have been limitedly addressed so far. The well-known hand lay-up technique has produced the laminates and the test samples prepared from the laminate are subjected to tensile, flexural, hardness, and impact strength properties. Based on the experimental work of the composites made in the laboratory, the fiber matrix ratio of 60:40 has revealed the best attributes in terms of higher mechanical strengths compared to the composites with fiber matrix ratio of 40:60 and 50:50 and the data obtained have been substantiated using scanning electron microscope analysis.

Damage and failure mechanisms of hybrid carbon fiber and steel fiber reinforced polymer composites

Fiber-reinforced plastics (FRPs) are widely used due to their superior properties but often suffer from brittle failure and poor structural integrity under impact loads. Metal fiber hybrids (MFH) offer a solution, but understanding their structure–property relationships remains challenging. This research provides a comprehensive mechanical characterization of a stainless steel-carbon fiber hybrid (SCFRP) embedded in epoxy resin, with a particular focus on the failure mechanisms and their influences. Therefore, the mechanical properties of the material, as well as the propagation and damage of the fracture, are investigated. In addition, three main failure mechanisms are identified and analyzed. The failure mode of a SCFRP laminate can be influenced by its composition, architecture, and specimen size and result from a combination of the blast effect of the brittle failing carbon fibers, the magnitude of the associated damage, and the movement of the fracture gap formation initiated by the carbon fiber failure.

Compressive failure mechanisms in unidirectional fiber reinforced polymer composites with embedded wrinkles

The present study examines how wrinkles affect a composite material’s compressive failure behavior. Uni-directional carbon fiber-reinforced polymer (UD-CFRP) composites with artificially induced wrinkles were fabricated by placing laminate strips in specific positions. The geometry and placement of these strips were varied, resulting in 18 different wrinkle configurations. Through extensive experimental testing, it was observed that the compressive strength decreased significantly, ranging from 20% to 73%, depending on the specific wrinkle configuration. The experimental results were found to align well with existing analytical models. Additionally, the study examined how the wrinkle characteristics affected the final kink bandwidth, angle, and inclination. Fractographic studies on the failed specimens revealed various damage modes at different length scales, including kinking, delamination, buckle delamination, crushing, fiber pullout, matrix cracking/failure, and fiber failure. Based on these findings, it is emphasized that the geometry of the wrinkles and the aforementioned damage modes at different length scales must be accounted for while developing a numerical model to predict the compressive behavior of the composite accurately.

Multifunctional basalt fiber reinforced polymer composites with in-situ damage self-sensing and temperature-sensitive behavior

In this work, a multifunctional basalt fiber reinforced polymer composite (BFRP) with damage self-sensing and temperature-sensitive behavior was developed. Firstly, carbon nanotubes (CNTs) were deposited on basalt fibers (BF) by electrostatic self-assembly. Then, strong shear forces were applied during melt mixing with polyarylene ether nitrile (PEN) to construct a structure of CNTs surrounding the BF (CSB). This CSB structure endowed the composite with a low percolation threshold (0.82 wt% CNTs), a high conductivity (1.53 × 10−2 S/m at 1.12 wt% CNTs) and enhanced mechanical properties. The combination of resistance and acoustic emission real-time measurements confirmed that the composite achieved an excellent damage self-sensing capability with a maximum gauge factor (GF) of 7.68. Moreover, the composite exhibited a temperature-sensitive behavior with a temperature coefficient of resistance (TCR) of 0.542 %/°C. This study provides a significant guidance for the development of multifunctional BFRP with damage self-sensing and temperature sensitive behavior.