Polymer Composites Research Articles

Thermomechanical Assessment of Recovered PA12 Powders with Basalt Filler for Automotive Components

Additive manufacturing processes allow for precise and efficient production, but it is estimated that one-third of the materials used results in waste. Further improvement in a sustainable perspective could come from the ability to manage these scraps and from the exploration of different routes for recovery and reuse. The Selective Laser Sintering process is particularly sensitive to this issue due to the waste ratio which can reach a very high quantity of not-sintered virgin powders. In this research study, recovered PA12 powders, preliminarily characterized through thermal and mechanical analysis, were mixed with 15% basalt powder to improve their aspect and thermomechanical resistance. The influence of basalt powder (BP) on mechanical properties as well as on the thermal stability of polyamide12 (PA12) powder composites was investigated. A study conducted on mechanical properties showed that polymeric composites’ stiffness and hardness were influenced by adding filler, thus improving mechanical parameters. On the other hand, the application of thermogravimetric analysis allowed us to determine the composite’s thermal stability. The objective is to obtain a recovered fully biobased material that could be used to substitute the petroleum-derived polymeric ones currently employed in the production of interiors and shells in the automotive sector.

Integrating the in vitro antioxidant activity of Polyacrylonitrile/Polyindole composites

AbstractIn this study, five compounds belonging to the Polymer composites (PCs) family, have been prepared with different amounts of polyacrylonitrile and polyindole in the composite. The PCs have inherently bactericidal activity, owing to the nitrile and indole groups. Antioxidant activity was assessed by using reducing power activity, superoxide radical scavenging activity and hydroxyl radical scavenging activity. In our study, butylated hydroxy toluene (BHT), ascorbic acid and α‐tocopherol, which are considered synthetic standard antioxidants, were used to compare antioxidant activity. In addition, since it is known that the MDA levels resulting from the oxidation of fats in Saccharomyces cerevisiae yeast cells are inversely proportional to the antioxidant properties, it gave an idea about the in vitro antioxidant properties of the new synthesized PCs. Reducing force capacity, superoxide radical scavenging activity and hydroxyl radical scavenging activity were found to be higher at 100 μg mL−1 concentration compared to 50 μg mL−1 concentration.

Factors affecting flexural and impact strength of natural fiber reinforced polymer composites: a review

The surging demand for energy-efficient products and their environmental implications are important propelling factors contributing to the growing popularity of natural fiber-reinforced polymer composites (NFRPCs) in several domains. NFRP composites diversification significantly influenced the study and their development in recent years. The intrinsic characteristics of natural fibers have posed difficulties in the growth and use of NFRPCs. A significant amount of study has recently been performed to solve these sorts of problems in order to enhance the performance of NFRPCs and their uses. This review article aims to provide a comprehensive overview of the chemical composition of natural fibers, their physical and mechanical characteristics, and factors affecting the flexural and impact strength of NFRPCs, such as type of fiber, weight percentage of fiber, fiber geometry, surface treatments, stacking, hybridization, orientation, fillers, and information accomplished with them. The product life-cycle evaluation and sustainability development of plant-based NFRCs and the growing uses of NFRPCs, focusing on the automobile sector, are also explored. Finally, multiple perceptions were concluded with the expectation that this study may contribute to future improvements in the flexural and impact strength of NFRPCs.

Occurrence, characteristics and distribution of microplastics in commercial marine fishes of the Bay of Bengal

The study aimed to assess and characterize microplastics (MPs) in muscles, guts, and gills of six commercially important marine fish from the Bay of Bengal. FTIR was utilized to identify MP's polymer compositions. A total 7085 MPs identified, where tuna exhibited the highest count and Bombay duck had the lowest. MPs abundance (MPs/g) was ranged from 1.56 ± 0.39 to 7.16 ± 1.36 in muscles, 1.91 ± 0.32 to 4.46 ± 0.75 in guts, and 2.36 ± 0.24 to 6.53 ± 1.58 in gills. The predominant MPs were 1–5 mm size (33.33–62.78 %), white/transparent color (18.45–54.63 %), filament shapes (75.00–94.71), and fiber types (73.21–94.71 %). FTIR revealed MPs 58.89 % polyethylene, 21.67 % polypropylene, 17.22 % polyester, and 2.22 % non-plastic compositions. Cluster analysis grouped two species with 50 % similarity, while PCA indicated significant variations among principal components (14–69.4 %) highlighting the dominance of fiber, particles, and 0.5–1.0 mm MPs in the fish tissues. The prevalence of MPs in seafood underscores measures to safeguard both the marine ecosystem and human health.

Smart Carbon Fiber-Reinforced Polymer Composites for Damage Sensing and On-Line Structural Health Monitoring Applications.

High electrical conductivity, along with high piezoresistive sensitivity and stretchability, are crucial for designing and developing nanocomposite strain sensors for damage sensing and on-line structural health monitoring of smart carbon fiber-reinforced polymer (CFRP) composites. In this study, the influence of the geometric features and loadings of carbon-based nanomaterials, including reduced graphene oxide (rGO) or carbon nanofibers (CNFs), on the tunable strain-sensing capabilities of epoxy-based nanocomposites was investigated. This work revealed distinct strain-sensing behavior and sensitivities (gauge factor, GF) depending on both factors. The highest GF values were attained with 0.13 wt.% of rGO at various strains. The stability and reproducibility of the most promising self-sensing nanocomposites were also evaluated through ten stretching/relaxing cycles, and a distinct behavior was observed. While the deformation of the conductive network formed by rGO proved to be predominantly elastic and reversible, nanocomposite sensors containing 0.714 wt.% of CNFs showed that new conductive pathways were established between neighboring CNFs. Based on the best results, formulations were selected for the manufacturing of pre-impregnated materials and related smart CFRP composites. Digital image correlation was synchronized with electrical resistance variation to study the strain-sensing capabilities of modified CFRP composites (at 90° orientation). Promising results were achieved through the incorporation of CNFs since they are able to form new conductive pathways and penetrate between micrometer-sized fibers.

Environmental sustainability and waste conversion of Prosopis juliflora fibre-reinforced ZnO nanofiller particulates PLA composite- mechanical and thermal analysis

The presence of large quantities of Prosopis juliflora (PJ) fibers in natural habitats presents substantial threats to the environment and economies of numerous developing countries. Utilizing natural fibers in polymer composites can effectively enhance their characteristics. The primary objective of this study is to create a composite material by combining Prosopis Juliflora (PJ) fiber with a polylactic matrix that has been combined with zinc oxide nanofillers. The fabrication process will involve the hand layup technique. In order to have a comprehensive understanding of the mechanical characteristics, thermal behavior, and thermal stability of the PJ composite, it is necessary to undertake additional investigations. The results showed that the inclusion of zinc oxide filler enhanced the tensile strength (67.29 MPa), flexural strength (64.27 MPa), compressive strength (56.79 MPa), and impact energy (34 J) in sample S5. Additionally, the thermal properties, including thermal conductivity, thermal expansion, and short-term heat resistant capacity, were also improved by the addition of zinc oxide filler in sample S5. The deterioration temperature of the PJ composite was determined to be between 312 and 342 °C using thermogravimetric analysis. The failure mode of the PJ composite was investigated using scanning electron microscopy.

Self-Healing Composites: A Path to Redefining Material Resilience—A Comprehensive Recent Review

Polymeric composites are prone to undergoing damage, such as microcracks, during their operation, which can ultimately lead to catastrophic failure. To contradict such a problem, efforts have been carried out, by the scientific community, towards developing self-healing composites that, by mimicking biological systems, can autonomously and prematurely repair flaws, extending the durability and improving the security of materials. The present review explores the progress made in this area, focusing on extrinsic self-healing methods, as these can be employed to a variety of materials. Reservoir-based techniques, which resort to capsules, hollow fibers or microvascular networks, and thermoplastic-based ones are overviewed, prioritizing innovative approaches made in recent years. At last, promising practical applications for self-healing composites are highlighted and future challenges and opportunities are pointed out.

Precise tailoring of thermoresponsive characteristics: Revealing ATRP opportunities for controlled poly(ethylene glycol)-based monomers composition in cyclodextrin-containing polymers

Star-shaped copolymers consisting of centrally located β-cyclodextrin and fifteen side chains containing di(ethylene glycol) methyl ether methacrylate (DEGMA) and poly(ethylene glycol) methyl ether methacrylate (OEGMA500) distributed statistically were synthesized using three different atom transfer radical polymerization (ATRP) techniques. For the first time, the use of β-cyclodextrin as a naturally-derived core for thermoresponsive polymeric drug delivery systems was thoroughly investigated depending on the chosen ATRP concept, focusing on precise control of the lower critical solution temperature (LCST) modulating the monomer content. The thermoresponsive properties of the received copolymers were investigated by UV–Vis and dynamic light scattering (DLS) measurement to determine the transmittance of solutions containing polymers with different monomer compositions and hydrodynamic diameter of prepared macromolecules upon temperature changes. The developed method allows for fine-tuning of the LCST by adjusting only the composition of the monomers. Synthesized copolymers were subsequently tested for residual copper catalyst content using atomic absorption spectrometry (AAS) to ensure compliance with the daily intake framework. The attained results showed negligible copper concentration in the purified products. Encouraged by these findings, cytotoxicity tests were conducted on normal fibroblast, cancer liver, and cancer breast cells, revealing no significant reduction in cell viability even at high polymer concentrations.

Seismic Performance Evaluation of Pipelines Buried in Sandy Soils Reinforced with FRP Micropiles: A Numerical Study

Unstable sandy soil poses significant challenges for buried pipelines, particularly due to the increased risk of displacement and stress-induced fractures resulting from soil settlement and earthquake-induced ground deformation. These concerns are especially critical in seismically active regions where underground infrastructure is at higher risk. Fiber-reinforced polymer (FRP) composites present a promising and sustainable alternative for deep foundations, offering durability and reduced maintenance costs compared to conventional materials. This study introduces a novel approach to enhancing the seismic performance of pipelines buried in sandy soils by numerically investigating a three-dimensional (3D) multipipe grouting micro anti-slide pile system, utilizing a polyurethane polymer slurry as the grouting material. Key parameters such as pile spacing, diameter, and length, along with the effects of soil wetting and various earthquake intensities, were examined under the influence of surface loads exerted by a fully loaded truck. The results demonstrate that using polymer micropiles significantly reduces soil and pipeline settlement by 15% to 50%, with larger pile diameters and lengths further decreasing settlement and strain on pipelines. While seismic excitation increases settlement, polymer grouting effectively mitigates this impact, leading to substantial reductions in settlement.

Optimizing the dielectric properties of polymer composites by constructing multi-dimensional fillers

The construction of multidimensional fillers provides new ideas for the development of composite materials. In this study, one-dimensional (La0.5Nb0.5)xTi1-xO2 ceramic nanorods (x-LNTO NRs) and 1-LNTO ceramic materials with three-dimensional fiber structure network (3D-1-LNTO) were prepared by electrospinning. These materials were used as fillers to prepare x-LNTO NRs/PVDF composites and 3D-1-LNTO/PVDF composites. Compared with the 1-LNTO NPs/PVDF composites, the 1-LNTO NRs/PVDF composites showed better dielectric properties, with a dielectric constant of 40 and a dielectric loss of 0.12 at a fill content of 60 wt%. The 3D-1-LNTO/PVDF composites achieved a high dielectric constant at a low filler content, the composite achieved a dielectric constant of 25 at a fill content of only 10 wt%, which is 2.5 times higher than that of pure PVDF. Compared with x-LNTO NRs, 3D-1-LNTO is more obvious for improving the dielectric properties of composites. The construction of continuous fiber network is the main reason for the enhancement of dielectric constant, and this study provides a new experimental idea for the construction of multi-dimensional high dielectric fillers.

Green hybrid materials from biomass waste: Distiller’s grains/epoxy vitrimer—Green synthesis, superior properties, and potential application in solar-thermal-electric generator

Distiller’s grains (DG) are a major biomass waste product in the ethanol and brewing industries, and have shown great potential as fillers for polymer composites. However, combining DG with polymer matrixes using traditional method often involves tedious pre-modification of DG and/or the use of costly coupling agents, significantly increasing the preparation cost of the final composite materials. In this study, we present an environmentally friendly approach for preparing a new type of green composite, termed distiller’s grains/epoxy vitrimer hybrid materials (EV@DG). This method eliminates the need for laborious pre-modifications of DG, as well as the use of solvents and coupling agents. The resulting EV@DG hybrid materials exhibit superior mechanical properties—approximately 90 % increase in tensile strength and 400 % increase in Young’s modulus—along with high thermal stability (Td,max of 357.63°C) and excellent reprocessability. Moreover, the EV@DGs demonstrate impressive photothermal conversion capabilities, positioning them as promising candidates for the fabrication of solar-thermal-electric generator.

Investigation of Gnetum Gnemon and Ramie Natural Fiber on the Mechanical Properties of Composites with the Combination of Aramid and Carbon Fiber as Reinforcement for Military Personnel Applications

Every equipment infrastructure in a TNI unit will be needed to support an operation in the defence system to maintain the integrity of the Unitary State of the Republic of Indonesia. Personal protective equipment is needed for a war operation’s safety or continuity. Protective components made from composite fibers have the advantage of being resistant to corrosion caused by the environment. The natural and carbon fibers will be mixed/reinforced with epoxy resin to become composite materials. This study aims to identify Gnetum Gnemon fiber composites with carbon fiber and aramid fiber to determine the mechanical properties of the composite material resulting from a collision. Natural fiber Gnetum gnemon has not been widely studied as a reinforcing material for polymer composites. Gnetum gnemon fiber chemical composition is hemicellulose approx. 25%, 40% alpha cellulose, 10% lignin and 3-5% benzene extractive. Its density is quite light, 1.2087 g/cm³ - 1.8069 g/cm³. Because this fiber has a continuous fiber structure and a strong natural weave, its use is still minimal. Special treatment such as alkali treatment on Gnetum gnemon, can increase the strength of natural fibers. Due to its exceptional mechanical properties, Kevlar or aramid fibre are extensively used in industrial and military applications. The aramid fiber exhibited a transversely anisotropic nature in a small strain range, with its stress-strain behavior as linear and elastic. The anisotropic nature of the aramid fiber was due to its high tensile-to-shear modulus ratio. The high strength and modulus were also found to be scattered due to the larger distribution of defects in the longer fiber. Epoxy resin is a type of polymer characterized often by one or more epoxide functional groups, with at least one of the epoxide functional groups acting as a monomer and terminal unit of the polymer within the structural chain.

Enhanced energy harvesting of fibrous composite membranes via plasma-piezopolymer interaction

Electroactive sites and crystallinity play a key role to improve the energy conversion performance of piezoelectric polymeric composites. However, these characteristics are attained through time-consuming thermal annealing (TA), which limits the practicality of flexible piezoelectric harvesters (f-PEHs). Here, a short-time plasma annealing (PA) technique was introduced to piezoelectric composite fibers (PCFs) for rapid crystallization and enhanced electroactive β-phase of polymer. The percentage of change in crystallinity of 10-minute PA treated PCF is 20 % compared to TA-treated PCF (annealing time = 2 h), which results in a higher voltage of 2.4 times and current of 3.8 times than the TA-based f-PEH. Finite element analysis confirmed the optimal PA treatment duration and superior performance of PA-treated PCFs. Further PA treated f-PEH was tested for vibration sensor by attaching it to a circulator pipe, confirming its high potential for accurately detecting variations in flow velocity (8–28 L/min). These results demonstrate that PA is an efficient technique for producing high-performance f-PEHs with an increased crystallinity (Xc =22.81 %) in a short time (10 minutes), offering a practical solution for consumer electronic devices and wireless sensors.

Highly Interconnected Thermal Conduction Highway for Highly Thermally Conductive and Mechanically Strong Polymeric Composites.

Industrial implementation of highly thermally conductive polymeric composites has been hindered by several hurdles, such as the low intrinsic thermal conductivity (TC) of polymers, the use of expensive thermally conductive fillers, and difficulty in processing composites with high filler loading. In this study, we introduce a straightforward fabrication method for a high TC polymeric composite with a programmed internal structure of a highly interconnected thermal conduction highway (HITCH) by the simple addition of partially cured resin fragments into the conventional filler/resin combination. Critical variables, such as the concentration of the added resin fragments and the local concentration of hexagonal boron nitride (hBN) in the HITCH, as well as the packing density of the fragments, were systematically tuned to maximize the TC with the use of the least amount of the filler. Careful choice of the compositions enabled a significant TC enhancement of the composite by 2.6 times (6.5 W/mK) compared to the value of the conventional composite at the same overall concentration of hBN (∼2.5 W/mK). Finally, a composite with high TC (∼12 W/mK) and strong tensile strength (∼22.6 MPa), which is good enough for most practical thermal management applications, could be successfully fabricated with the use of the least amount of the filler (∼34 wt %). The comprehensive study of the HITCH composite here can be easily extended to other combinations with various fillers and matrices and may provide a library to researchers looking for advanced materials for future thermal management systems.

Enhancing fiber/matrix interface adhesion in polymer composites: Mechanical characterization methods and progress in interface modification

The interface between the fiber and polymer matrix is a crucial region that plays a major role in the mechanical performance of fiber reinforced polymer composites (FRPCs) materials. The properties of this zone are recognized to have a significant influence on the fracture and failure of FRPCs. As a result, strong adhesion at the interface is required for effective stress transfer and load distribution within the composite material. In light of this, the aim of this work is to provide an up-to-date review of test methods for assessing fiber/matrix interface adhesion in FRPCs under static and dynamic loadings, along with advancements in interface modification techniques. At the outset, we give an overview of the different modification treatments used thus far, alongside interface testing methods, in order to optimize fiber/matrix compatibility, improve interfacial bonding and scrutinize their impact on interfacial adhesion properties. Particular attention is then focused on the description of the main mechanical characterization techniques used to assess the fiber/matrix interfacial properties. In the final outlook, we highlight the key findings and discuss potential directions for characterization of the fiber/matrix interface.

Process parameter interaction study for mechanical strength of r-HDPE filled calcium carbonate composites

Abstract The increasing issue of plastic waste disposal has drawn attention to the urgent requirement for sustainable solutions. At the heart of this problem is polyethylene, a crucial industrial resin that has significant implications for recycling. This study aims to explore the feasibility of using recycled high-density polyethylene (rHDPE) derived from waste carpet as a sustainable alternative material for structural applications that undergo mechanical loads. The primary focus of this research is to incorporate calcium carbonate an easily obtainable and cost-effective inorganic mineral filler into the rHDPE. This will enhance mechanical strength. Calcium carbonate (CaCO3) is widely recognized for their reinforcing properties in various polymer composites, and in addition not only improves the mechanical strength of the blend but also reduces the environmental impact associated with plastic and waste carpet disposal. Our experimental approach involves preparing samples with varying compositions of rHDPE and calcium carbonate. This includes carefully considering extrusion process parameters such as screw speed and melting temperature. Mechanical testing was performed using a universal testing machine following the ASTM standard. The findings of this research are expected to open up new avenues for innovative strategies in reducing plastic waste and promoting the sustainable utilization of waste carpets thereby contributing to the broader field of environmental sustainability

Higher-order sensitivity analyses to understand the role of FE input parameters on the simulation of composites in progressive fracture tests

With the rise of data-driven engineering methods, such as machine learning, a comprehensive understanding of the underlying data fed into these algorithms is required for effectively applying these methods. This study presents two highly efficient Finite Element (FE) models that operate at different length scales, based on Continuum Damage Mechanics (CDM). The combination with Random Sampling-High Dimensional Model Representation (RS-HDMR) enables the determination of influential FE input parameters and their correlations to simulate Fibre Reinforced Polymer (FRP) composites subjected to a variety of progressive fracture tests in tension and compression. The results indicate that laminate-based models utilise the FE input parameters efficiently where all parameters are found to be influential. On the other hand, only fibre-related properties are relevant in ply-based FE models, with all input parameters related to transverse properties deemed to be non-influential. The findings of this study aid in identifying suitable fracture tests for a meaningful calibration and validation of CDM-based FE models. Moreover, the study lays the foundation for understanding the role of input parameters within data-driven methods, and for developing efficient reduced-order models or surrogates for uncertainty quantification on the damage tolerance of FRP composites.

Improved interfacial properties of carbon fiber reinforced epoxy resin composite by in‐situ self‐assembled mental‐phenolic networks

AbstractThe chemical modification of carbon fiber surface often uses toxic reagents and harsh reaction conditions, while the preparation process of metal‐phenol networks (MPNs) is simple, rapid, non‐toxic and harmless, which provides a direction for alleviating environmental problems. In this study, tannic acid (TA) was coordinated with Fe3+ to form MPNs, which was coated on the surface of carbon fibers through π‐π interaction. The results indicated that oxygen functionalities on the surface of the MPN coating can facilitate better adhesion between the carbon fiber and the epoxy resin, when the molar ratio of TA to Fe3+ is 1:3 and the pH is 4, the interlaminar shear strength (ILSS) performance of the composite material reaches its optimal level. In addition, a green and non‐destructive method is provided for the surface modification of carbon fiber, which can effectively optimize the interfacial properties of carbon fiber reinforced polymer (CFRP) composites.

The interface dewetting process of particulate filled polymer composite

AbstractDewetting is one of the most common damage modes in particulate filled polymer composite, which greatly damages the structural integrity of the composite and leads to the deterioration of its mechanical properties. Studying the dewetting evolution process of composite is of great significance for evaluating the meso damage degree of composite and suppressing the development of dewetting damage. This article constructs an axisymmetric cylindrical cell model of a single particle inclusion matrix, derives the interface dewetting evolution process of the model under uniaxial tensile loading condition, and analyzes the influence of model geometric parameters and external loading conditions on the dewetting process. Subsequently, numerical models were constructed at both micro and meso scales, and dynamic tensile calculations were performed to analyze the correlation between the dewetting rate, porosity, and mechanical performance. Finally, a cylindrical cell specimen was designed to observe the interface dewetting evolution under uniaxial tensile conditions, confirming the conclusions of theoretical analysis and numerical simulation.Highlights Constructed a theoretical model for the dewetting process of interface. Conducted numerical analysis of dewetting process at both meso and micro scales. Designed interface dewetting experiment and analyzed the dewetting process.

Evaluation of Different ZX Tensile Coupon Designs in Additive Manufacturing of Amorphous and Semi-Crystalline Polymer Composites

The layer-by-layer deposition of molten polymer filament in fused deposition modeling (FDM) has evolved as a disruptive technology for building complex parts. This technology has drawbacks such as the anisotropic property of the printed parts resulting in lower strength for parts printed in the vertical Z direction compared with the other two planes. In this manuscript, we attempt to address these challenges as well as the lack of standardization in sample preparation and mechanical testing of the printed parts. The paper focuses on process parameters and design optimization of the ZX build orientation. Type I tensile bars in ZX orientation were printed as per the ASTM D638 standard using two (2B) and four (4B) tensile bar designs. The proposed design reduces material loss and post-processing to extract the test coupons. Printing a type I tensile bar in the ZX orientation is more challenging than type IV and type V due to the increased length of the specimen and changes in additional heat buildup during layer-by-layer deposition. Three different polymer composite systems were studied: fast-crystallizing nanofiller-based high-temperature nylon (HTN), slow-crystallizing nanofiller-based polycyclohexylene diethylene terephthalate glycol-modified (PCTG), and amorphous carbon fiber-filled polyetherimide (PEI-CF). For all the polymer composite systems, the 2B showed the highest strength properties due to the shorter layer time aiding the diffusion in the interlayers. Further, rheological studies and SEM imaging were carried out to understand the influence of the two designs on fracture mechanics and interlayer bonding, providing valuable insights for the field of additive manufacturing and material science.