Polymer Matrix Composites Research Articles

Exploring the influence of specimen types on the intralaminar fracture behavior of fiber-reinforced polymer matrix composites

The accurate determination of fracture toughness of fiber-reinforced composites is critical for the assessment of structural integrity. Although there have been many studies on the intralaminar fracture behavior of composites, satisfactory results have not yet been obtained regarding the influence of specimen types. In this paper, commonly used fracture specimens (DCT, CT, ESET, pin-loaded SENT and clamped SENT specimen) are applied to study their applicability in the fracture behaviors of composites with different orientations. And the impact of data processing methods for the area method, GC-compliance and GC-stress intensity factors on fracture performance was analyzed. The results showed that the above three data processing methods have obtained relatively consistent fracture properties. Different specimens obtained significantly various results, showing a gradually decreasing trend from clamped SENT, ESET, pin-loaded SENT, CT to DCT. Furthermore, considering that the clamped SENT specimen is closest to the Mode-I fracture toughness obtained from the DCB specimen, and there is no compression damage in the experiments under different orientations, this specimen type is the most recommended specimen. Finally, the failure mechanisms of carbon fiber-reinforced composite under different specimen types and orientations were revealed. As the orientation angle increases (β from 0° to 90°), the failure mode gradually transitions from matrix cracking and interface debonding to matrix shear and fiber fracture. The above achievements will contribute to a deeper understanding of the intralaminar fracture process and failure mechanism of fiber-reinforced composites.

Quantification of delamination resistance data of FRP composites and its limits

Quantitative delamination resistance data of fibre-reinforced polymer-matrix (FRP) composites for quasi-static or cyclic fatigue loads are determined under different loading modes and load rates, respectively. Such data find use, e.g., in FRP materials’ development, materials’ selection, assessment of durability, or structural design. Round robins during test development yielded repeatability and reproducibility (coefficients of variation) of roughly 10 to 25%. This scatter has several different sources. Intrinsic material variability amounts to a few percent at best, at least for advanced manufacturing processes. This intrinsic scatter is essential for material comparisons and structural design. Measurement resolution specified in standardised test procedures yields a maximum of 4–5% variability. Most of the remaining scatter comes from other, extrinsic sources. Test operator actions, e.g., choice of test set-up, manual data acquisition or data analysis can yield extrinsic scatter. Damage mechanisms during delamination initiation and propagation act on the micro- and meso-scale, typically a few micrometer to a few hundred micrometer in size, with corresponding time-scales estimated to between a few tens of nanoseconds and a few microseconds. Defect size-scales are hence several orders of magnitudes lower than test specimen and structural scales, respectively. Predictive capability of models using such test data for structures are, therefore, limited. Major issues are up-scaling from straight beam-like specimens to larger shell-like structures, possibly with complex shape and varying thickness as well as from unidirectional fibre orientation to multidirectional lay-ups.

The effect of nanocellulose and silica filler on the mechanical properties of natural fiber polymer matrix composites

Natural fiber-reinforced polymer matrix composites recently got great attention in biomedical applications due to their inherent characteristics such as biocompatibility, lightweight, and biodegradability. However, natural fiber composites suffer from poor mechanical properties and weak interfacial adhesion. It is well documented that the addition of nanofiller has improved the mechanical properties of different synthetic fibers such as glass and carbon composites. The main objective of this paper is to study nanofillers' effect on the mechanical properties of unidirectional false banana fibers reinforced polymer composites. The filler materials, crystalline nanocellulose fibrils, and crystalline nanosilica particles were extracted from sugarcane bagasse and its byproducts. The composite samples were fabricated by adding the nanofillers in unidirectional natural fibers arranged in four fiber orientations (0°, 0o/90o ±45o, and quasi-isotropic), and their tensile, flexural, compression strength, thermal stability, and void content were measured following ASTM standards. The results revealed that adding nanofillers increased the tensile, flexural, and compressive strengths by 16 % (98.83 Mpa), 11 % (161.60 Mpa), and 23 % (114.62 Mpa), respectively. Similarly, at 0° orientation, the addition of nanoparticles enhances the tensile, bending, and compressive modulus by 30 % (15.43 Gpa), 12 % (13.52 Gpa), and 60 % (42.6 Gpa), respectively. On the other hand, the void content was reduced with the addition of nanofillers. The results also revealed that composites with crystalline nanosilica particle fillers had superior thermal stability compared to crystalline nanocellulose fibril fillers. The overall results of this research give the confidence that nano particle-filled natural fiber composites can be used for bio-based engineering applications, such as prosthetic sockets.

Structure and tribological behavior of a polyetherimide/polytetrafluoroethylene matrix filled with negative thermal expansion zirconium tungstate particles

Thermal expansion mismatch stresses may be a reason for premature failure of sealing and bearing components made of polymer composites that are rubbed against metallic surfaces at elevated temperatures. It is of particular importance for polymer matrix composites loaded with anti-friction inclusions of polytetrafluoroethylene (PTFE) that possesses high coefficient of thermal expansion. In this regard, a study was undertaken to elucidate the effect of the thermal mismatch on wear and friction of amorphous polyetherimide (PEI) matrix loaded with either polytetrafluoroethylene (PTFE) particles (i) or PTFE particles covered with negative thermal expansion zirconium tungstate (ZT) α-ZrW2O8 (ii) at temperatures 23 °C, 120 °C and 180 °C. The ball-on-disk testing scheme was used according to standard with AISI 52100 steel balls rubbed against a polymer composite disks at normal force P = 5 N and sliding velocity V = 0.3 m/s. The PEI/PTFE/ZT composite demonstrated a tendency for wear rate (WR) reduction in sliding at 120 °C and 180 °C as compared to corresponding WR enhancement on the PEI/PTFE. The rationale is provided that the ZT additive effectively reduced thermal expansion of the PTFE in the PEI matrix and thus improved wear resistance of the composite. New thermal expansion-controlled wear and friction instability mechanism has been proposed and discussed.

Damage assessment in composite plates using extended non-destructive self-heating based vibrothermography technique

Self-heating based vibrothermography (SHVT) is a promising non-destructive technique for inspecting polymer-matrix composites (PMCs) in circumstances with limited external heating feasibility, functioning under the resonant frequency excitation. This study broadened the applicability of SHVT technique for two-dimensional (2D) PMCs by examining its sensitivity and effectiveness in detecting and quantifying damage within 2D laminated composites across nine different scenarios. Atwo-step algorithm based on the concepts of the boundary of effective thermograms, and the maximal temperature ratio was proposed to methodically choose the optimal raw thermogram from a large set of registered thermograms for each scenario. The issues linked to blurred damage signatures in the raw infrared (IR) images adversely affected the overall sensitivity and accuracy of SHVT. Implementing the algorithm based on central moments improved the overall damage detectability using this technique. Additionally, the introduced hit/miss metric enabled the damage identification and quantification for all scenarios.

Impact response and compression-after-impact properties of foam-core sandwich composites incorporating scrap tyre rubber particles

Integrating scrap rubber particles as fillers into polymer matrix composites offers a cost effective and environmentally sustainable pathway to manage tyre waste through the creation of value-added products. This research explores the low-velocity impact (LVI) response and compression after impact (CAI) properties of rubberised foam-core glass fibre-reinforced epoxy (GFRE) sandwich composites. Syntactic foam cores integrated with rubber particles were manufactured using vacuum-assisted resin transfer moulding (VARTM). The compression properties of rubberised foam core, vital for resisting impact damage during LVI, were examined. Results show more than 40% reduction in compression strength and modulus of the syntactic foam upon the inclusion of 33 wt.% rubber particles. The LVI response and residual compression properties of rubberised foam-core composites were also evaluated. Rubberised foam cores caused a marginal reduction in the peak impact force and led to approximately 60% reduction in the delamination area. The pre-impact compression strength was unaffected by rubber particles within the core as the GFRE face sheets carried most of the compression load. Post-impact compression strength was slightly higher in rubberised foam-core composites due to reduced delamination. Digital Image Correlation (DIC) analysis tracking of the strain evolution during CAI experiments revealed the stress-raising effect of the impact damaged region. This study showcases sustainable scrap tyre management through the inclusion of rubber particles into foam-core composites without substantially reducing in-plane compression properties before or after low-velocity impact.

Determination of elastic moduli of polymeric materials using microhardness indentation

Young's modulus of elasticity (or stiffness, E) is an important material property for many applications of polymers and polymer-matrix composites. The common methods of measuring E are by measuring the velocity of ultrasonic pulses through the material or by resistance to flexure, but it is difficult for ultrasound to penetrate polymers that contain filler particles, and flexural measurements require large specimens that may not mimic the clinical case. Thus, it may be difficult to determine E using conventional techniques. It would be useful to have a relatively rapid technique that could be applied to small specimens, highly filled materials, and even specimens cured in situ. We suggest using a microhardness indentation technique that was originally developed for ceramic materials. We tested two unfilled rigid polymers, four resin composites, and four unfilled polymers with lesser hardness for this study. The study found that greater Vickers hardness loads yielded more consistent results than lesser loads. We developed a modified equation for E based on Knoop microhardness indentations. We concluded that laboratories may use a microhardness indenter to estimate the elastic moduli of polymers and resin composites. The results support our initial hypotheses that the slope of the equation relating the indentation parameter and the hardness/elastic modulus ratio was different for polymers and resin composites than for ceramics; however, the intercept is the same irrespective of the material tested.

Fabrication and characterization of a composite material from polymer matrix using citrus limetta fiber

Natural fibers, known for their excellent mechanical properties, non-abrasiveness, affordability, high specific strength, environmental friendliness, and biodegradability, are increasingly being considered as potential replacements for synthetic fibers like glass and carbon. This study investigates the use of Citrus limetta peel fibers to develop and characterize a polymer matrix composite. The fibers were extracted, purified, and coated with epoxy resin, then developed into composites using the hand layup method and cured in an oven. Mechanical tests, including hardness, impact, tensile strength, and compression strength, were conducted to assess the composites. The results showed that fiber reinforcement significantly enhanced mechanical stability, with compression strength and ultimate tensile strength reaching 231.39 MPa and 22.68 MPa, respectively. Microstructural analysis using scanning electron microscopy (SEM) and moisture absorption tests were also performed. Additionally, Ansys workbench software was utilized for further analysis. The study concludes that Citrus limetta peel fibers are a viable reinforcement material for polymer matrix composites, offering enhanced mechanical properties. This research is relevant for applications in industries seeking sustainable and high-performance composite materials.

Tough, high-strength, flame-retardant and recyclable polyurethane elastomers based on dynamic borate acid esters

With the wide application of polyurethane elastomers, it is necessary to develop recyclable, fire-retardant polyurethane elastomers with great mechanical properties to comply with industrial requirements. Herein, we fabricated a flame-retardant, recyclable, strong yet tough polyurethane elastomer (PIDB-1) based on dynamic borate acid esters. The introduction of phosphaphenanthrene and boron-containing groups endow PIDB-1 with great flame retardancy, as reflected by it achieving the vertical burning (UL-94) V-0 rating. The PIDB-1 film shows high visible light transmittance, and its transmittance reaches 90 % at the wavelength of 800 to 900 nm. The tensile strength of PIDB-1 is 54.9 MPa, and its toughness reaches 207.8 kJ/m3, indicative of superior mechanical properties. Meanwhile, the dynamic borate acid esters allow the PIDB-1 elastomer to possess physical and chemical recyclability. When using PIDB-1 as a polymer matrix for carbon fiber-reinforced polymer composites, the carbon fibers can be fully recycled. This work provides an integrated design strategy for creating transparent, flame-retardant, recyclable polyurethane elastomers combining high strength and toughness based on dynamic borate ester bonds, which is expected to find wide applications in different industries.

Evaluation of the mechanical properties of hybrid composites reinforced with plant fibers

The incorporation of plant fibers into the matrix plays an interesting role. Natural fibers have been widely used as reinforcements in polymer matrix composites. Among all reinforcing fibers, natural fiber-based hybrid composites have attracted the attention of researchers as high-potential reinforcing materials for composite materials. These fibers are easily available in the form of agricultural products. Natural fibers are inexpensive, durable and lightweight materials for composite applications. In this experimental work, sisal fibers and date palm fibers were used as reinforcement in different ratios to fabricate hybrid composites by compression molding technique while maintaining a total fiber loading of 20 % by weight. Tensile tests, flexural tests, and impact tests were carried out, water absorption was also determined. The results obtained show that the composite composed of a combination of 16% sisal fibers and 8% date palm fibers has better tensile properties with a stress value of 6.88 N/mm2 and a value of Izod impact of 43.218 J/m. As well as both composites showed a better bending stress value of 67.29 N/mm2, the water absorption test was carried out for four days with 120 hours analysis. This research focuses on the fact that specimen-2 containing 16% sisal and 8% date palm fibers absorbs less water than other composites.

Efficient 3D temperature field prediction and visualization for AFP process analysis in composite structures

AbstractProcess modeling is an indispensable tool for establishing a foundation for process optimization and enhancing the quality of products. Analyzing the thermoforming process of polymer matrix composites presupposes the acquisition of accurate thermal histories. This paper introduces a numerical solution based on the finite difference (FD) model to predict the temperature field of angle‐ply composite structures during automated fiber placement (AFP) process along the machining trajectory. The proposed method incorporates three‐dimensional hybrid boundary conditions and considers temperature‐dependent material properties, significantly improving efficiency compared to the finite element (FE) model and overcoming challenges related to complex boundary conditions and anisotropic heat transfer in analytical solutions. Real‐time temperature measurement experiments were conducted to validate predictions, and further a specific temperature control strategy that meets process requirements was explored. In summary, the paper introduces a novel approach to address the temperature field in complex composite structure manufacturing processes.Highlights A novel 3D finite difference model predicts the temperature field in automated fiber placement. Improved prediction accuracy by managing complex boundary conditions. Effectively handled anisotropic heat transfer in complex composite structures. Superior efficiency over existing numerical methods. Developed a model‐based strategy for optimal temperature control within ±5°C.

Sensor-Enhanced Thick Laminated Composite Beams: Manufacturing, Testing, and Numerical Analysis.

This study investigates the manufacturing, testing, and analysis of ultra-thick laminated polymer matrix composite (PMC) beams with the aim of developing high-performance PMC leaf springs for automotive applications. An innovative aspect of this study is the integration of Fiber Bragg Grating (FBG) sensors and thermocouples (TCs) to monitor residual strain and exothermic reactions in composite structures during curing and post-curing manufacturing cycles. Additionally, the Calibration Coefficients (CCs) are calculated using Strain Gauge measurement results under static three-point bending tests. A major part of the study focuses on developing a properly correlated Finite Element (FE) model with large deflection (LD) effects using geometrical nonlinear analysis (GNA) to understand the deformation behavior of ultra thick composite beam (ComBeam) samples, advancing the understanding of large deformation behavior and filling critical research gaps in composite materials. This model will help assess the internal strain distribution, which is verified by correlating data from FBG sensors, Strain Gauges (SGs), and FE analysis. In addition, this research focuses on the application of FBG sensors in structural health monitoring (SHM) in fatigue tests under three-point bending with the support of load-deflection sensors: a new approach for composites at this scale. This study revealed that the fatigue performance of ComBeam samples drastically decreased with increasing displacement ranges, even at the same maximum level, underscoring the potential of FBG sensors to enhance SHM capabilities linked to smart maintenance.

Orientation of Chitin Nanofibers Dispersed in a Thermoplastic Polymer Matrix Through Dry Thermal Stretching

AbstractNanostructures derived from structural polysaccharides, such as cellulose and chitin, are notable for their sustainability, lightweight properties, and superior mechanical attributes. The macroscopic performance of these materials largely depends on the orientation of nanostructures. This study explores the preferential orientation of chitinous nanofibers (NFs) within a thermoplastic polymer matrix (PM) comprising poly(N‐vinylpyrrolidone) and glycerol, achieved through dry thermal stretching techniques. Altering the PM composition enables the modulation of the system's glass transition temperature (Tg). Chitin NFs are effectively dispersed within the PM, with their orientation enhanced by stretching at temperatures ≈30 °C above the Tg of the composites, resulting in an elongation at rupture (ε) of 105%. Under similar temperature conditions, composites with chitosan NFs show strong interactions with the PM, hindering the stretching process (ε = 10%). In contrast, composites with acetylated chitin NFs demonstrate increased stretchability (ε = 170%) but have insufficient interactions to stabilize their orientation. These interactions, identified as hydrogen bonds through FTIR, vary significantly based on the functional groups present on the NF surfaces. This variation is supported by DSC and dynamic mechanical analysis. Oriented ChNFs hold potential for bioactive applications.

Development of a sustainable polymer composite: enhancing properties of waste plastic with ground tire rubber reinforcement

The growing interest in utilizing waste for composite development has prompted investigations across social, economic, and environmental domains. This study focuses on utilizing recyclable waste plastic materials and micro-sized ground tire rubber (GTR) of varying sizes (600 μm, 300 μm, and 150 μm) to create a polymer matrix composite (PMC). Employing a thermal blending technique, the manufacturing process adjusts the composition ratios of polymer and GTR from 90:10 to 50:50. Subsequently, Energy Dispersive Spectroscopy (EDS) is utilized to analyze the PMC composition, while Fourier-transform infrared spectroscopy confirms functional group and chemical structure. The study demonstrates significant improvements in various properties upon adding GTR to High-Density Polyethylene (HDPE) and Low-Density Polyethylene (LDPE) composite materials. For HDPE-GTR composites, the melting temperature (Tm) ranged from 120.29 °C to 138.53 °C, crystallization temperature (Tc) from 102.84 °C to 127.14 °C, and enthalpy of melting (ΔHm) from 70.96 to 139.67 J g−1. Crystallinity (Xc) varied from 48.43% to 52.96%. In LDPE-GTR composites, Tm ranged from 106.08 °C to 129.57 °C, Tc from 90.27 °C to 112.20 °C, ΔHm from 75.59 to 142.53 J g−1, and Xc from 51.59% to 54.05%. Moreover, mechanical properties such as tensile strength, flexural modulus, and impact strength exhibited enhancements with GTR addition to the polymer matrix. These findings underscore the potential of sustainable waste utilization, advancing environmentally friendly and resource-efficient composite materials.

Advances in the structure and preparation of electromagnetic shielding composites with carbon-based filler polymers

The growth of electronic equipment applications, such as aerospace weaponry, wireless base stations, and 5G communication technologies, has led to serious electromagnetic interference (EMI) and pollution problems. These issues can cause equipment overload and damage. Carbon-based fillers are commonly used as conductive fillers in EMI shielding materials due to their low cost, lightweight and flexible nature, high thermal and electrical conductivity, corrosion resistance, and ease of processing and molding. This paper aims to provide theoretical support for future research by identifying the major trends in the recent advancements of carbon-based filler polymer composites for electromagnetic shielding from the years 2020 to 2024, specifically in filler selection, multifunctional interface design, and preparation methods. Furthermore, this paper discusses the shielding principle of EMI shielding materials, the influence of different kinds of carbon-based fillers on the EMI shielding effect of polymer matrix composites, and the challenges and progress of their preparation methods. In the end, it concludes by proposing future research directions to overcome current technological barriers and further develop EMI shielding materials for industrial applications.

Self-Lubrication Mechanism of Surface-Textured Polymer-Matrix Composites under the Induction of Frictional Stress.

Polymer-matrix composites have been widely used in the manufacture of seals, bearings, electrical insulators, and self-lubricating films as engineering applications move toward lighter weight, higher strength, and corrosion resistance. However, the high-speed shear effect of the friction pairs in relative motion leads to localized heating of the polymer surface, resulting in deformation or softening of the device. Herein, acer mono maple and canna leaves were used as templates to construct polymer-matrix sulfonated polyether-etherketone/polytetrafluoro-wax (SPEEK/PFW) composites with a surface-textured structure. As the bionic texture reduces the level of direct contact between the friction pairs, the frictional thermosoftening of SPEEK occurs in the localized areas of the bumps and leads to the release of PFW stored in textures, resulting in the formation of a soft polymer sliding layer in the worn area and greatly enhancing the frictional stability. By investigation of the tribological properties of textured SPEEK/PFW composites under different loads and sliding speeds, the mechanisms from surface wear to matrix softening and spontaneous construction of a slipping layer are summarized. The results of scanning electron microscopy and three-dimensional profilometer characterization of the wear scars show the surface state of SPEEK/PFW after friction, revealing the friction-thermotropic deformation of the surface texture. The results of this study not only improve our understanding of the frictional heat-induced surface self-lubrication mechanism of textured polymer composites but also provide a reference for the development of multiphase hybrid polymer-matrix composites with excellent self-lubrication properties.

Verification and validation of dielectric mapping technique for non‐destructive evaluation of polymer matrix composites

Verification and validation of dielectric mapping technique for non‐destructive evaluation of polymer matrix composites

Stabilization of polyacrylonitrile-based fiber with a quasi-traveling microwave applicator

This study introduces a novel microwave applicator and optimized processing conditions to enhance the stability of Polyacrylonitrile (PAN)-based precursor fiber (PF). The innovative microwave applicator facilitates the propagation of the electromagnetic (EM) field akin to a quasi-traveling wave, thus circumventing standing wave nodes. This ensures a uniform thermal distribution and broadens the heating zone. Utilizing this applicator, the PF undergoes thermal stabilization in a streamlined two-step process, completing in just 13 min, a significant improvement over the conventional 90-min process. This not only saves manufacturing time, promoting energy efficient manufacturing but also aligns with the global trend towards green energy and lightweight carbon fiber-reinforced polymer matrix composites, potentially catalyzing rapid economic growth. Fiber characterization through Raman spectroscopy (RS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and complex permittivity measurements reveals that the microwave-processed fiber meets the standard of commercial stabilization fiber (SF).

A Comprehensive Review of Recent Developments on the Natural Fiber Reinforced Polymer Matrix Composites for Automotive and Sports Application: Materials, Processes and Properties

Now a days, the world has been evolving and adapting to advance technology; as a result, the development and expansion of Composite materials have been growing day by day.. Natural fibres are a feasible and eco-friendly alternative to synthetic fibres for polymer composite reinforcing. Materials are attractive because they are economical, environmentally friendly, abundant in nature, and have mechanical properties[60]. Natural fibres are given first priority above all other types of fibres due to their appealing qualities include biodegradability, minimum cost, environmental friendliness, high strength-to-weight ratio in engineering goods, and low health risks. An overview of recent trends in physio mechanical characteristics, thermal properties, morphological behaviour, surface treatment, design optimisation with the ANOVA technique, the effect of Mercerization and SEM analysis, microstructural interfacial adhesion, and the various methodologies used to measure these properties. Keywords: Natural fiber polymer composites, Physio mechanical properties, SEM Analysis, Thermal properties, ANOVA technique, Applications.

A review on integration of carbon fiber and polymer matrix composites in 3D printing technology

Three-dimensional (3D) printing applications obtained by combining the lightness, high strength, and durability of carbon fiber with polymer matrix composites provide various industrial advantages. These advantages offer new design and production opportunities for automotive, aviation, space, medical devices, and many other industrial fields. This review article discusses material innovations in 3D printing technology with a focus on the integration of carbon fiber and polymer matrix composites. After examining the current state and future potential of 3D printing technology, the properties and advantages of carbon fiber and polymer matrix composites and the difficulties encountered with their integration into the 3D printing process were examined. In conclusion, this review article comprehensively discusses the current status, advantages, challenges, and future directions on the integration of carbon fiber and polymer matrix composites in 3D printing technology. This article can be an important resource for industry professionals and researchers in materials science and engineering.