Polymer Composites Research Articles

Enhanced properties of low-density polyethylene composites reinforced with Bridelia ferruginea fibers: effect of low temperature fiber acetylation

In this study, lignocellulosic fibres were extracted from Bridelia ferruginea (BF), a shrub which can be found in sub-Saharan Africa with a view to probing the potential application of the fibres. The chemical properties of the BF were chemically modified by acetylation to evaluate the potential applications of the fibre reinforced polymer composites. The unacetylated and acetylated fibres were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) and Thermogravimetric Analysis (TGA) to compare thermal and crystallographic properties after acetylation over different lengths of time. The acetylated fibres with the most promising properties were used for the fabrication of a polymeric composite. The mechanical properties of the fibre-reinforced polymer composites were studied by hardness and dynamic mechanical measurements. Four types of polymeric samples were prepared for the mechanical measurements: unreinforced polymer (Control) polyester, ATBF/LDPE, ACEBF3/LDPE, ACEBF/LDPE. The SEM micrographs revealed that acetylation led to defibrillation. FTIR peaks at 1250 cm−1 and 1371 cm−1 confirmed that acetylation had occurred. The fibres possessed high crystallinity index of 75% which reduced as time of acetylation increased. Acetylation at mild conditions of 70 °C for 3 h did not result in significant damage to the fibres. For the hardness measurements, the values of the micro-hardness of the composite samples increased from 0.20 GPa to 0.29 GPa. The acetylated fibres tend to further resist deformation due to its dispersion in the polymer matrix providing a stronger cross-linking effect. The properties unearthed show that BF appears to be a promising raw material for the production of polymer composites.

Fabrication and mechanical performance investigation of jute/glass fiber hybridized polymer composites: Effect of stacking sequences

The green, biodegradable, and cost-effective properties of natural fiber-reinforced polymer composite materials have attracted significant interest when compared to synthetic polymer composites. Jute is a naturally occurring bast fiber that is inexpensive, durable, and often utilized. In contrast, glass is a composite material that is frequently used in various applications, despite its high cost and potential environmental risks. Owing to jute's superior mechanical properties, there is a great deal of potential for combining it with glass, which would lower the amount of glass used and the composite's overall cost. This study employed bleached jute fabric and non-woven glass fabric to develop neat jute, neat glass, and hybrid composites by using different stacking sequences. The composites were fabricated utilizing a thermoset polymer matrix by following the hand layup process. Subsequently, an investigation was carried out to examine the mechanical, physical, thermal, and morphological properties of these composites. Out of the developed samples, the neat jute presents the least tensile and bending strength at 31.35 MPa and 41.138 MPa respectively, whereas the neat glass composite demonstrates exceptional tensile and bending strengths at 132.03 MPa and 184.86 MPa respectively. In the case of hybrid samples, they exhibited mechanical capabilities that fell between neat jute and neat glass, which was attributed to the combination of glass with jute fabric and the placement of glass as the outer layer. Apart from that, we observed that the moisture take-up% and thermal conductivity of hybrids composite were within 4–4.3% and 0.28–0.32 Wm−1 K-1 respectively. Moreover, thermogravimetric analysis and morphological behavior were also assessed. However, this study suggested that jute and nonwoven glass fabric with different stacking sequences may be combined to create a reinforced hybrid composite that may have potential use in furniture, interior design, and inner sections of cars.

A comprehensive analysis and risk evaluation of microplastics contamination in Australian commercial plant growth substrates: Unveiling the invisible threat

In Australia, quality standards for composts and potting mixes are defined by AS4454-2012 and AS3743-2012. These standards outline key parameters, including physicochemical properties, nutrient content, and plant toxicity. However, they do not address emerging pollutants like microplastics (< 1mm). This study investigates the prevalence and characteristics of MPs in commercial plant growth substrates (PGS), including nineteen potting mixes and five composts, revealing a significant occurrence of MPs, with concentrations ranging from 233 to 7367 particles Kg-1 and an average of 1869 ± 109 particles Kg-1. MPs categorized by shape, size, and color, with fragments (491 ± 34 particles Kg-1), white colour (3700 ± 917 particles Kg-1), and size 500µm being predominant. The polymer composition was diverse, with polyethylene being the most prevalent, followed by polypropylene and others. Polyterpene, Polyalkene, Pentaerythritol, and Propylene glycol were identified in PGS for the first time. The structural equation model showed that physicochemical properties like pH, EC, TOC, and heavy metals influence MPs abundance and characteristics. The Polymer Risk Index and Pollution Load Index indicated varying risk levels among the samples. These findings highlight the need to address MPs contamination in PGS to ensure ecosystem safety and human health. Environmental ImplicationsThe study reveals significant microplastic contamination in Australian commercial PGS, with compost exhibiting higher levels than potting mixes. Application of these contaminated substrates can lead to microplastic release, which can further alter soil properties, disrupt microbial communities, and leach environmental toxins. Current regulations primarily target larger plastic items, neglecting the issue of microplastics (<1mm). The findings underscore the necessity for updated standards and quality controls for commercial PGS. Enhancing public awareness and improving waste sorting are crucial steps to mitigate contamination. Effective source separation is essential for producing high-quality compost and potting mixes. Collaborative efforts among policymakers, industries, and communities are vital for advancing waste management practices and environmental protection.

Vascular bundle-structured polymeric composites with fire-safe, self-detecting and heat warning capabilities for power batteries thermal management

The trend of miniaturization and integration poses challenges to the thermal management of electronic devices, requiring high thermal conductivity and potential fire safety, etc. In this study, inspired by plant vascular structure, we developed a polymer composite with a vertical vascular bundle structure via a sacrificial template method and subsequent assembly of transition metal carbides/nitrides (MXene) nanosheets and phytic acid (PA) coordinated cobalt ions (Co2+) complex. The embedded MXene and PA@Co exhibit multilayer multiscale structural features, forming heat transfer channels and protective cells within the composite. The resultant composites possess high out-of-plane thermal conductivity (∼1.54 W‧m−1‧k−1) and excellent flame retardancy, including self-extinguishing, and significantly reduced heat and smoke release. Interestingly, the MXene vascular bundle structure imparts heat early warning capabilities and intelligent damage self-detection, suggesting an effective means of preventing early-stage fires and real-time monitoring of composite structural and functional integrity. Such biomimetic strategies enable new insights into the designing of multifunctional, intelligent polymer composites.

Fabrication of core–shell nickel ferrite@polypyrrole composite for broadband and efficient electromagnetic wave absorption

Herein, nickel ferrite@polypyrrole (NiFe2O4@PPy) composite was prepared by a simple two-step route of solvothermal synthesis and in-situ oxidation polymerization reaction. The results of micromorphology analysis showed that the obtained NiFe2O4@PPy composite had a unique core–shell structure, good magnetic performance and electrical conductivity. Furthermore, the as-prepared magnetic/conductive NiFe2O4@PPy composite exhibited notably enhanced electromagnetic wave (EMW) absorption performance than pure NiFe2O4 and PPy. When the filling ratio was 17.5 wt% and the matching thickness was 2.24 mm, the optimal minimum reflection loss (RLmin) of −56.25 dB and a broad effective absorption bandwidth (EAB) of 5.2 GHz were achieved for NiFe2O4@PPy composite. With slightly increasing the matching thickness to 2.6 mm, the maximum EAB of 7.12 GHz could be reached. Additionally, the probable EMW absorption mechanism was elucidated. Therefore, this work could provide a valuable reference for the preparation of magnetic ferrite/conductive polymer composites as broadband and high-efficiency EMW absorbers.

Effect of chitosan and natural materials on properties of polyvinylchloride for blood bags applications

Abstract Polyvinyl chloride is the most common material used in the manufacture of blood bags, and chitosan and wheat extract were used to improve the biological, physical, mechanical and optical properties of the manufactured blood bag. Chitosan was added at three concentrations (1, 2, and 3%) to the PVC matrix sample, and the wheat extract was supplemented to the sample having the highest properties to study its effect. It was found that the addition of chitosan led to an increase in tensile strength, as well as a significant increase in inhibition against the bacterial activity of two types of bacteria (S. aureus and C. albicans), and the ability to absorb water, but the addition of wheat extract led to a very small decrease in absorbency. Also, the supplement of chitosan and wheat extract reduced the transparency of the manufactured blood bag. All samples were characterized as not having the ability to non-hemolytic in the hemolysis test. All the results of polymer blends and polymer composite were compared with the pure PVC and commercial blood bags as reference samples.

Enhancement of the thermal, electrical properties and mechanical properties of graphene doped novel copolymers bearing coumarin side groups

In this study, a new monomer 3-acetyl coumarin-7-ylacrylate (Ac-Kum) was synthesized. A series of copolymer were prepared by using (Ac-Kum) and methyl methacrylate (MMA) in different ratios. The structure characterization of the compounds was carried out by FT-IR, 1H-NMR and 13C-NMR spectroscopic techniques. Graphene doped polymer composites were prepared at different rates (1%, 2% and 5%). The thermal behavior of the polymer composites were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) methods. Thermal stability of 1%, 2% and 5% graphene composites of homopolymer was determined as 324 °C, 345 °C and 350 °C, respectively. The dielectric properties of the polymer composites were investigated as a function of frequency. Dielectric constant, dielectric loss and ac conductivity values of homopolymer were determined as 6.13, 0.11, 1.02×10−09 S/cm and 5% graphene composite were determined 49.30, 7259, 9.26×10−07, respectively. Microhardness tests were carried out under a load of 100 g and in 10 seconds. The microhardness values were calculated by taking the average of the microhardness values taken from the surface of the samples from five different points. The highest microhardness value is the 5% graphene added P(Ac-Kum) sample. Wear tests were carried out with a pin-on-disc wear tester under single load (10N) and in dry conditions with a total sliding distance of 10 meters and a sliding speed of 5 mm/sec. Disc samples with a diameter of 13 mm were placed in the sample holder part of the test device. The highest wear resistance sample is the P(Ac-Kum) 5% graphene composite.

Rate-dependent mechanical and self-monitoring behaviors of 3D printed continuous carbon fiber composites

3D printed continuous carbon fiber reinforced polymer (CFRP) composites offer great advantages in structural health monitoring (SHM) owing to their flexibility in complex structure fabrication. Considering the many prospective aerospace applications, tensile experiments were designed to study their mechanical and self-sensing behaviors under a wide range of strain rates. The turning points in the resistance vs strain curves reveal the damage evolution of the specimens and divide the deformations into linear straining and damage evolution regions. Fiber elongation and fiber contact reduction dominate the resistance increase in the linear straining region and the resistance curve behaves linearly. But fiber breakage is the predominant factor in the damage evolution region, yielding a concave resistance curve. Strength, fracture strain, and resistance variation are found to display significant strain rate dependencies that increase with increasing strain rate. Numerous microcracks are formed and evolved into secondary cracks under dynamic loading. This process absorbs more strain energy and produces more carbon fiber breaks, sustaining a higher fracture strain and resistance variations. A model is developed to describe the strain- and strain rate- dependent resistance behaviors, and the predicted results agree well with experimental data. The outcomes of this work contribute to the application of 3D printed continuous CFRP composites in SHM.

Stress-strain behaviour of pre-damaged concrete confined with natural fibre reinforced polymer

In recent years, using environmentally friendly construction materials has become a new trend in structural engineering. This research presents the application of natural fibre reinforced polymer (NFRP) composites for repairing damaged structural concrete members. The compressive behaviour of pre-peak damaged concrete confined with two types of NFRP composites was investigated. The tensile properties of jute fibre reinforced polymer (JFRP) and sisal fibre reinforced polymer (SFRP) were examined and compared with those of carbon fibre reinforced polymer (CFRP) using coupon tests. Subsequently, a series of pre-damaged concrete cylinders, confined with JFRP, SFRP, and CFRP, were subjected to uniaxial compression tests. The results showed that JFRP and SFRP are effective in providing confinement to pre-peak damaged concrete. The strength and ductility of pre-peak damaged concrete confined with NFRP increased with the number of NFRP layers. The cost-effectiveness of FRP-confined concrete was also evaluated, with JFRP being the most economically efficient. The eco-strength efficiency (ESE), defined as the increased compressive strength per unit of CO2 emissions, shows that JFRP is the most effective. This highlights JFRP's potential for sustainable construction. Finally, the compressive strength models were proposed. The models demonstrate improved accuracy in predicting the peak compressive strength of pre-peak damaged concrete confined with NFRP compared to existing models.

Numerical investigation on machining of additively manufactured CFRP composite with different build orientations and layer widths

Additive manufacturing (AM) is now a widely researched manufacturing technology in the past two decades to adopt in industry for its added advantage of customization and adopting complex geometries with comparatively low buy-to-fly ratio. Carbon fiber reinforced polymer (CFRP) composite has found applications in different high-performance industries for its greatest benefit of high strength-to-weight ratio. Additive manufacturing of CFRP composite (AM-CFRP) opens up the possibility of enhancing mechanical strength using different printing orientations and enables producing complex shapes maintaining sustainable manufacturing perspective. However, Limitation of AM parts of having surface irregularities and questionable dimensional accuracies. To use AM-CFRP parts in high precision assembly or industrial applications, post processing machining is often required to meet the customers’ specification of geometrical tolerances and acceptable surface finish. In this study, the influence of AM parameters on machinability of AM-CFRP composite has been evaluated using finite element analysis (FEA) based numerical simulation. The slot milling operation was simulated with a tungsten carbide end milling tool and AM-CFRP workpiece with four different printing directions, i.e., 0°-90°, 45°-135°, 0°-90°-45°-135°, two different layer widths, i.e., 50 µm and 100 µm, and two in-fill patterns, i.e., solid and perforated structures. The machinability of the 3D printed CFRP has been analyzed based on cutting forces, stress at first contact and maximum stress generation, and temperature increases at the interface during slot milling of AM-CFRP under different AM parameters. Evolution of failure mechanisms of AM-CFRPs under various machining conditions, such as, delamination, matrix rupture etc., have been discussed and chip and burr formation mechanisms have been analyzed. Finite Element analysis (FEA) package ABAQUS/Explicit was used to model 3D micro slot milling operation of AM-CFRP workpiece with appropriate damage and constitutive models, such as, damage initiation, progression and cohesion in adjacent passes and layers.

Long-term investigation on the daily variability of microplastic concentration and composition - Monitoring in the effluent of a wastewater treatment plant

The discharge of treated wastewater into receiving waters by wastewater treatment plants (WWTPs) is considered as one of the main pathways for microplastics (MPs) to enter the environment. To gain a better understanding of the temporal variability of MPs in WWTP effluents, this study investigated the concentration and composition (size, shape and polymer type) of MPs in the effluent of a German WWTP over the course of one month. 24-hour mixed samples were collected daily by a custom built automated sampling unit for MPs. Particles and fibers ≥11 μm were analyzed using Fourier transform infrared microspectroscopy. The MP concentration showed large daily fluctuations and ranged between 9.64 103 m−3 and 8.44 104 m−3 MPs over the study period. However, there was no significant correlation between the MP concentration and the precipitation or discharge from the WWTP. In contrast to the MP concentration, the MP composition in terms of size and shape was consistent over the study period. There were strong correlations between the time series of the polymer types polypropylene, polyethylene, polystyrene, polyester, ethylene-vinyl-acetate, cellulose artificially modified as well as the polymer cluster acrylates/polyurethanes/varnish. The time series of polyamide showed no significant correlation with the time series of any other polymer type. This study established a one month long high-resolution time series of MP concentration and composition, and thus provides a valuable basis for future research on the temporal variability of MP inputs into the environment from WWTP effluents.

Comparison of mechanical properties of bagasse fiber reinforced styrenic polymer composites

Comparison of mechanical properties of bagasse fiber reinforced styrenic polymer composites

Ar[formula omitted]i-Textile composites: Role of weave architecture on mode-I fracture energy in woven composites

This paper investigates the impact of weave architectures on the mechanics of crack propagation in fiber-reinforced woven polymer composites under quasi-static loading. Woven composites consist of fabrics/textiles containing fibers interwoven at 0 degrees (warp) and 90 degrees (weft) bound by a polymer matrix. The mechanical properties can be tuned by weaving fiber bundles with single or multiple materials in various patterns or architectures. Although the effects of uniform weave architectures, like plain, twill, satin, etc. on in-plane modulus and fracture energy have been studied, the influence of patterned weaves consisting of a combination of sub-patterns, that is, architected weaves, on these behaviors is not understood. We focus on identifying the mechanisms affecting crack path tortuosity and propagation rate in composites with architected woven textiles containing various sub-patterns, hence, Arχi(ar.kee)-Textile Composites. Through compact tension tests, we determine how architected weave patterns compared to uniform weaves influence mode-I fracture energy of woven composites due to interactions of different failure modes. Results show that fracture energy increases at transition regions between sub-patterns in architected weave composites, with more tortuous crack propagation and higher resistance to crack growth than uniform weave composites. We also introduce three geometrical parameters — transition, area, and skewness factors — to characterize sub-patterns and their effects on in-plane fracture energy. This knowledge can be exploited to design and fabricate safer lightweight structures for marine and aerospace sectors with enhanced damage tolerance under extreme loads.

Experimental studies of absorption properties of polymer composites based on core–shell fillers with hybrid shells

Microwave absorbing properties of polymer composites based on core-shell fillers with ultra-high molecular weight polyethylene core and GNP-carbonyl iron, GNP-cobalt oxide Co3O4, GNP-micro-sized MoS2, and GNP-barium hexaferrite BaFe12O19 hybrid shells were investigated in the frequency range of 40–60 GHz. Scanning electron microscopy sizing of the constituent particles in the composites showed the characteristic dimension of micron for Fe particles while Co3O4 and BaFe12O19 particles are found to be much smaller (nanometer-sized); MoS2 particles mostly form agglomerates and have diverse shapes and varying from 70 nm to 3–4 μm sizes. The shielding properties of composite materials (CMs) with 30 wt % Fe (Co3O4,MoS2, BaFe12O19) + C wt. % GNP/PEwith the GNP concentration c in the range of 1–5 wt% of nanocarbon are weakly frequency dependent. But the analyzed composites interaction with the electromagnetic radiation reveals significant influence of both the nanocarbon content and the additional dielectric or magnetic component type in the shell materials on the shielding parameters. The calculated values of the effective absorption coefficients Aeff for the investigated composites with different hybrid shells have shown that at 3 wt % GNP in the composite with 30 % Co3O4Aeff increases greatly and reaches 0.75, exceeding the correspondent values for the 30%BaFe12O19+GNP system. The primary contribution of absorption to the shielding characteristics of the investigated polymer CMs based on core-shell fillers with hybrid shells constitutes good prospects of applications.

Durability of carbon- and glass- fiber reinforced thermoplastic polymer composites: A literature review

Durability of carbon- and glass- fiber reinforced thermoplastic polymer composites: A literature review

Enhancing interfacial locking of the CF and PBPESK resin by in-situ electrochemical deposition of MOF nanoparticles

The interfacial bonding of carbon fiber reinforced polymer composites plays a critical role in the overall performance of the composites. Poor interfacial bonding leads to catastrophic damage of composites when subjected to external loads. In this study, three-dimensional (3D) NH2-UiO-66 nanoparticles in-situ synthesis on the carbon fiber (CF) surface using an electrochemical method was achieved facilely and efficiently to enhance the interfacial adhesion of CF/PBPESK composites. The influence of incorporating 3D NH2-UiO-66 nanoparticles into the interphase on the interfacial and mechanical properties of carbon fiber reinforced composites was systematically investigated. The NH2-UiO-66 nanoparticles significantly increased the carbon fibers surface energy. The flexural, interlaminar shear and interfacial shear strength of the N–CF–6min/PBPESK composite were improved by 19 %, 31 %, and 93 %, respectively, compared to the D-CF/PBPESK composite. Furthermore, the interfacial failure mechanism of the composites was investigated. This approach offered a simple and efficient strategy for the in-situ synthesis of interfacial phase characterized by robust mechanical locking effects.

Prediction of Tensile Properties of Natural Fiber Reinforced PP Hybrid Composites by Facca-Kortschot-Yan (FKY) and Palsule Equations

Abstract Natural fiber reinforced polymer hybrid composites are advanced materials for commercial and engineering applications. Rule of hybrid mixtures has been applied to develop Facca-Kortschot-Yan (FKY) Equation and Palsule equation for predicting tensile strength and modulus of these hybrid polymer composites. This study predicts the values of tensile strength and modulus of a few natural fibers reinforced polypropylene hybrid composites by these two equations and compares them with the reported experimental values.

Digital Image Correlation Analysis of Fatigue Degradation of Layered Polymer Composites (Polyetheretherketone/Polyetherimide, PEEK/PEI) with Carbon-Fiber Fabric Prepreg

In this work, the relationship was considered between the structure and cyclic loading resistance of a layered composite consisting of PEI (PEEK) plate/PEI (PEEK) film/PEI-impregnated carbon-fiber fabric prepreg/PEI (PEEK) film/PEI (PEEK) plate by analyzing the time variation in the parameters of mechanical hysteresis loops calculated using digital image correlation. It was shown that the polyetherimide-based layered composite has low fatigue life under cyclic loading (0.8 of the yield strength), resulting from incompatible deformation between the PEI plates and the prepreg due to a layer interface formed by low-melting TecaPEI film. In the PEEK layered composite, the layer interface was formed by neat PEEK energy director and therefore had a little amount of defects, due to which the load was well transferred from the PEEK plates to the middle reinforcement layer. As a result, the fatigue life at a load level of 0.8 of the yield strength corresponded to high-cycle fatigue (more than 86000 cycles).

Hybridization and its transformative role in bamboo fiber reinforced polymer composites: a review

Hybridization and its transformative role in bamboo fiber reinforced polymer composites: a review

Studying the Spectral Properties of Luminescent Polymer Composites Doped with Boron Difluoride Curcuminoids

Studying the Spectral Properties of Luminescent Polymer Composites Doped with Boron Difluoride Curcuminoids