Properties Of Polymer Composites Research Articles

Regulation of Mechanical Properties of Conductive Polymer Composites

Regulation of Mechanical Properties of Conductive Polymer Composites

Comprehensive Study of Mechanical, Electrical and Biological Properties of Conductive Polymer Composites for Medical Applications through Additive Manufacturing

Conductive polymer composites are commonly present in flexible electrodes for neural interfaces, implantable sensors, and aerospace applications. Fused filament fabrication (FFF) is a widely used additive manufacturing technology, where conductive filaments frequently contain carbon-based fillers. In this study, the static and dynamic mechanical properties and the electrical properties (resistance, signal transmission, resistance measurements during cyclic tensile, bending and temperature tests) were investigated for polylactic acid (PLA)-based, acrylonitrile butadiene styrene (ABS)-based, thermoplastic polyurethane (TPU)-based, and polyamide (PA)-based conductive filaments with carbon-based additives. Scanning electron microscopy (SEM) was implemented to evaluate the results. Cytotoxicity measurements were performed. The conductive ABS specimens have a high gauge factor between 0.2% and 1.0% strain. All tested materials, except the PA-based conductive composite, are suitable for low-voltage applications such as 3D-printed EEG and EMG sensors. ABS-based and TPU-based conductive composites are promising raw materials suitable for temperature measuring and medical applications.

Development and properties of bio-based polymer composites using PLA and untreated agro-industrial residues

This research developed a bio-based polymer composite using polylactic acid (PLA) and agro-industrial residues from coffee by-products (without chemical modification and the use of coupling agents or stabilizers). Agro-industrial residues, such as spent coffee ground (SCG) and coffee silver skin (CSS) as filler, were added into the PLA matrix in different percentages by weight, from 0.5 to 10 wt%. The bio-composites were prepared using solvent-cast films and were characterized by various techniques, including FT-IR, TGA, DSC, XRD, SEM and mechanical tests. Bio-composites' formation was verified using FT-IR and SEM; the material showed good interfacial interaction, with percentages between 3 and 5 wt%. XRD and DSC determined the percentage crystallinity in the bio-composites. SEM found that the bio-composites form crystals, showing their limits after mechanical testing. The bio-composites exhibited enhanced thermal and mechanical properties compared to neat PLA.These bio-based composites show great potential for a wide range of applications in the food industry, including disposable and single-use materials, as well as food packaging. Moreover, their use can significantly contribute to the global demand for eco-friendly materials.

Photorheologic Silicone Composites with Adaptive Properties by Utilizing Light‐Degradable Organosilica Nanoparticles as Fillers

AbstractImplementing inorganic filler particles is a powerful method for improving the mechanical properties of polymer composites. The physical properties are determined by the interaction of the filler with the polymer. Thus, factors like the surface‐to‐volume ratio and surface modification are important. Besides the strategies of influencing these physical properties by a prior modification of the filler, this approach applies a post‐treatment of the composite. The present publication focuses on bringing stimuli‐responsive properties to a composite material by changing the chemical composition and structure of the filler particles. Instead of creating a responsive polymer, the concept is to use photo‐degradable organosilica nanoparticles that can change the mechanical properties of a polymer/filler composite after it has been prepared. After the synthesis of nitrobenzyl ether containing organosilica nanoparticles and the investigation of the photochemical processes, the preparation of the composites with silicones is described. Vinyl groups are attached to the surfaces to secure a homogeneous distribution of the filler particles inside the polymer matrix. After light‐induced decomposition, the mechanical properties are investigated. Other than expected, the material becomes stiffer, which is explained by an increase in the surface area of the silica particles, accompanied by the emergence of hydroxy groups that interact with the polysiloxane.

Plasma Treatment of Nanocellulose to Improve the Surface Properties.

Nanocellulose is among the most promising materials for enhancing the mechanical properties of polymer composites. Broad application is, however, limited by inadequate surface properties. A standard technique for tailoring the surface composition and wettability of polymers is a brief treatment with non-equilibrium gaseous plasma, but it often fails when treating materials with a large surface-to-mass ratio, such as cellulose nanofibers. In this paper, the theoretical limitations are explained, the approaches reported by different groups are reviewed, and the results are interpreted. The treatment of dry nanocellulose is limited by the ability of uniform treatment, whereas the plasma treatment of nanocellulose dispersed in liquids is a slow process. The methods for enhancing the treatment efficiency for both dry and water-dispersed nanocellulose are explained.

Investigations on the Mechanical, Morphological, and Thermal Degradation Properties of Alkali-Treated Polymer Composites Reinforced with an Areca Palm Leaf Stalk Fibers

Investigations on the Mechanical, Morphological, and Thermal Degradation Properties of Alkali-Treated Polymer Composites Reinforced with an Areca Palm Leaf Stalk Fibers

Effect of the Glass Fiber Orientation on Mechanical Performance of Epoxy based Composites

Composites are one of the most advanced and adaptable engineering materials. The strength of any composite depends upon volume/weight fraction of reinforcement, orientation angle and other factors. The present work focuses on the determination of the mechanical properties of pure epoxy and unidirectional glass fiber reinforced epoxy. Nowadays, glass fibers are being used in several engineering applications like electronics, aviation, automobile, sport industry etc. Glass fibers are having excellent properties like high strength, flexibility, stiffness, and resistance to chemical attack. With an increase in the content of unidirectional glass fiber volume the properties of unidirectional glass Fiber Reinforcement Polymer (GFRP) composite were improved. It may be used in different forms like chopped, woven mat, short fibers and long fibers etc. Each type of glass fiber has unique properties and is used for different applications. The mechanical and thermal properties of various polymer composites reinforced with glass fibers when subjected to mechanical loading have been studied and reported.

Advanced polymeric matrix utilizing nanostructured bismuth and tungsten oxides for gamma rays shielding

In this study, the shielding properties of novel polymer composites, developed by integrating glycidyl methacrylate with nanoparticles of bismuth oxide (Bi2O3) and tungsten oxide (WO3), were explored. The ability of the composites to attenuate gamma radiation was evaluated by measuring the emissions from Ba-133, Co-60, Cs-137, and Na-22. X-ray diffraction (XRD) spectra were obtained for both the pure polymer glycidyl methacrylate and the samples containing nanostructures of Bi2O3, Bi2O3/WO3, and WO3, and scanning electron microscopy (SEM) was used to analyze the samples. The incorporation of Bi2O3 and WO3 nanoparticles into the polymer glycidyl methacrylate matrix significantly enhanced the composites' ability to attenuate gamma radiation, as demonstrated by the increased linear and mass attenuation coefficients. The results showed good agreement between the experiment and the XCOM database. The composites exhibited significant efficiency in attenuating lower-energy gamma rays, which is particularly advantageous in the medical and nuclear industries.

Study of the effect of void defects on the mechanical properties of fiber reinforced composites

This study is to investigate the mechanical properties of fiber-reinforced polymer (FRP) composites considering void defects by adopting a representative volume element model. The results reveal that initial damage always sprouts at the interface, the void defects affect the location of the initial damage and are the dominant factor in determining the stress required for damage sprouting. In addition, the void defects as well as the neighboring debonding interfaces together determine the direction of the main damage evolution zone. The transverse tensile properties are most affected by the void defects, while the longitudinal tensile properties are least affected. In particular, the strength is more sensitive to void defects than that of elastic constants. In addition, the mechanical properties of high Fiber Volume Fraction (FVF) FRP composites are significantly stronger affected by void defects than those of low FVF FRP composites.

Evaluation of mechanical, thermal, and flammability properties in biochar-infused polymer composites from bael fruit and cashew shells: a comparative study

Evaluation of mechanical, thermal, and flammability properties in biochar-infused polymer composites from bael fruit and cashew shells: a comparative study

In situ growth of silver nanoparticles on carbon fiber by plasma–liquid interaction to improve performance of epoxy composites

Grafting nanomaterials on the carbon fiber (CF) surface is considered an effective strategy for enhancing the interfacial properties of CF-reinforced polymer composites (CFRPs). However, the mechanical properties of the CFs are often compromised during treatment. A new method for in situ growing silver nanoparticles (AgNPs) on the CF surface is proposed in this study. The CFs are first immersed in a low-viscosity silver nitrate solution to form a thin liquid film on the surface. Subsequently, using the abundant active particles in the plasma, the silver ions are reduced to silver atoms and grown into AgNPs on the CF surface. The tensile strength of CF@Ag was 38.74% greater than that of untreated CF, potentially due to the reparative action of AgNPs on defects in CF. The CF showed an evident improvement in surface wettability because of the AgNPs. Furthermore, the interfacial properties were noticeably improved, with the interfacial shear strength of CF@Ag increasing to 91.59 MPa, which was about twice that of pristine CF. Thus, the mechanical properties of composites are significantly improved (flexural strength increased by 190.74%). This study presents a non-destructive and convenient method for growing nanoparticles onto CF to establish a robust interface in CFRPs.

Exploring the influence of fiber orientation on the mechanical characteristics of polymer composites reinforced with banana and corn fibers

In recent decades, the utilization of polymer composites reinforced with natural fibers has seen a significant increase due to their durability, eco-friendliness, and favorable composite properties. This study investigates the influence of unidirectional and cross-directional fiber orientation on the mechanical properties of polymer composites reinforced with banana and corn fibers, fabricated through a hand-lay-up process. The research assesses the impact of fiber orientation on various mechanical properties, including density, porosity, tensile strength, flexural strength, and impact strength. The findings reveal that the higher densities of banana and corn fibers, in comparison to the epoxy matrix, contribute to increased overall weight density in the composites, with cross-directional fiber orientation leading to higher porosity. Moreover, cross-directional reinforcement orientation enhances tensile strength, resulting in a robust bond with the matrix. Composites with cross-directional corn fibers exhibit the highest ultimate tensile strength of 49.57 MPa, marking a significant improvement over other fiber configurations. Notably, unidirectional corn fibers outperform in flexural strength of 14.07 MPa, surpassing banana–corn, and banana–banana configurations by 268.32% and 32.73%, respectively, and cross-directional banana–corn hybrid composites exhibit superior impact strength measuring 5.31 kJ/m2 due to their ability to resist crack propagation. Whereas scanning electron microscopy micrographs of fractured samples reveal debonding, fiber pullout, and fiber scissoring as the root causes of sample failure under tensile load These insights provide valuable guidance for the design and application of composite materials.

Enhancing mechanical properties and tribological performance through boron carbide hybridization in Novolac matrix graphite composites under dry sliding condition

This study extensively investigates the effects of 10 wt% graphite reinforcement and varying B4C content (1 wt%, 2 wt%, 4 wt%) on the properties of Novolac matrix polymer composites prepared by mechanical milling-assisted hot pressing. The microstructures, wear surfaces, wear debris, and fracture surfaces of the produced polymer composites were examined using SEM and EDS. The density measurements were conducted according to the Archimed’s principle. Their tribological behavior was evaluated with a reciprocating ball-on-flat sliding wear test at 50 N, 75 N, and 100 N loads. After the wear tests, surface topography was analyzed in 3D with an optical profilometer. The results indicated that composites with 2 wt% B4C had the lowest specific wear rate and the highest wear resistance.

Tribological behavior of poly(ether ether ketone)/synthetic Eucommia rubber composites

AbstractOur previous study (Polymer Composites 2023, 44: 1252–1263) revealed the positive role of rubber in modifying the tribological properties of polymer composites. This concept was applied here by incorporating synthetic Eucommia rubber (TPI) to 3D printed polyether ether ketone (PEEK) skeletons with different infill densities. The formation of TPI/PEEK composite improved the friction and wear of PEEK matrix with some reduction in mechanical performance. The composite with 70% infill density is recommended in terms of its overall performance. Based on the morphological and chemical analysis, the composite's wear mechanism was discussed. The findings of this present study could pave a new route to modify friction‐reduction and anti‐wear performance of PEEK.Highlights Novel composites were successfully prepared from thermodynamically incompatible synthetic Eucommia rubber (TPI) and polyether ether ketone (PEEK). The tribological properties of TPI/PEEK composites were studied in association with the infill density of PEEK. The TPI rubber helped improve the friction and wear properties of PEEK thanks to its role in enhancing the formation of transfer films on the counter steel surface.

Thermorheological complexity in Nylon12‐Cork composites: Role of interfacial compatibilizer

AbstractHerein, we demonstrate how compatibilizers affect the thermorheological properties and morphology of engineering thermoplastic composites based on nylon and cork. Nylon12 was melt‐mixed with cork treated with four distinct compatibilizers with radically different chemical structures and compositions, respectively: (i) Octadecanamide (ODA), (ii) polyethylene‐graft‐maleic anhydride (PE‐g‐MA), (iii) polypropylene‐graft‐maleic anhydride (PP‐g‐MA), and (iv) (3‐aminopropyl)triethoxysilane (APTS). The rheological behavior was assessed using an oscillatory rheometer and the morphology was visualized using a scanning electron microscope. The rheological data were thoroughly analyzed using different formalisms based on empirical, phenomenological, and molecular origin, including the Carreau‐model, time–temperature superposition (TTS), Han plot, and van Gurp–Palmen (vGP) plot. It is observed that rheological data of neat nylon can be treated as themorheologically simple. However, the inclusion of cork makes the composite thermorheologically complex and increases the relaxation time (τ) by >50‐fold when compared to the neat polymer. As compatibilizers, ODA and PP‐g‐MA significantly lower τ, improve internal flow behavior, and demonstrate good cork distribution and dispersion. However, PE‐g‐MA does not affect the τ of composites significantly. The application of APTS as a compatibilizer enhances the interfacial interaction between Nylon12 and cork most significantly, which leads to a notable rise in τ, and the composite's elastic modulus surges by two orders in magnitude compared to neat Nylon. Additionally, the polymer melt flow becomes elastically dominant. Finally, it is observed that the Han plot offers a better insight into the correlation between changes in the thermorheological behavior and the microstructural modifications to the composites.Highlights Utilizing cork particles as a sustainable raw material for engineering thermoplastics. Quantifying compatibilizer's impact on rheological properties of polymer composite. Illustrating how interfacial interaction affects thermorheological complexity in composites. Visualizing morphological change in nylon‐cork composite with interfacial interaction. Producing lightweight engineering polymer composites using cork as a filler.

The effect of lubrication on the tribological properties of polymer composites for high contact pressure hydropower bearings

Premature failure of polymeric self-lubricating bearings is a limiting factor in the sustainable and continued operation of hydropower plants. In this work, the tribological performance of two novel polymer composites was studied with respect to commercially available materials. The materials were evaluated under dry and lubricated conditions, using water and an environmentally adaptive lubricant (EAL). The two tested commercial materials yielded a low dry sliding friction and wear. Under water lubricated conditions, the in-house developed polyphenylene sulphide (PPS) based composite provided an exceptionally low friction and a wear rate of a factor of 3 lower than the best performing commercial material. Using the EAL wear was reduced for most materials by up to 85%.

Anomalous Conductive Properties of Polymer Composites with Carbon Nanotubes: Why Power Laws Are Not Universal

The conductive properties of CNT/polymer composites have been extensively studied. However, the impact of CNT distribution in the matrix on the composite polarization remains underexplored and poorly understood. Since it is difficult to achieve a uniform distribution of CNTs in polymers, most researchers have focused only on indiscriminately aggregated states. In this article, a new blending method was suggested to prepare a series of epoxy resin-based composite samples with varying levels of CNT uniformity/aggregation and the same filling fractions. Notably, the permittivity values turned out to be inversely related to the composite uniformity: the lowest permittivity values were obtained in the most uniform formulation, and vice versa. With 0.1% CNT, the real part values of the most uniform and aggregated samples were 6.6 and 16.2 at 107 Hz and 11.6 and 370.5 at 101 Hz, respectively. For the filler content of 0.1–0.5%, the conductive properties were largely determined by the distribution of CNTs and not their content. Within the entire frequency range, the uniform sample with 0.2% CNT exhibited significantly lower permittivity than the aggregated sample with 0.1% CNT. These findings emphasize the importance of the aggregation factor and underscore the non-universality and limitations of the percolation theory and power laws. The observed phenomenon is best explained by the micro-capacitor model, or the Maxwell–Wagner polarization, and suggests that a significant portion of the literature in the field needs to be reconsidered.

Advancements in chemical modifications using NaOH to explore the chemical, mechanical and thermal properties of natural fiber polymer composites (NFPC)

Abstract Increasing environmental awareness and concerns about global warming have resulted in a significant demand for sustainable and eco-friendly resources, such as naturally available fibers, that can be suitable alternatives to petroleum/synthetic materials such as glass, carbon and Kevlar in reinforced composites. The exploration of natural fibers as reinforcements in composites is increasing in popularity, particularly in the development of transport and household components. However, natural fibers also have a few limitations that should be addressed appropriately, including lack of compatibility between fiber-matrix, fiber swelling, excess absorption of moisture, resistance to chemicals and fire. Consequently, various processes have been used to improve the fiber surface, to obtain a better fiber–matrix interface. The primary objective of this work is to review the impact that a 5 % NaOH (sodium hydroxide) treatment has on the chemical, mechanical, and thermal properties of natural fiber-reinforced composites (NFRC).

Probing the microstructural properties of metal-reinforced polymer composites

Abstract Microstructural analysis is an important technique to study the extent of interaction between metal fillers and polymers. The aim of this study is to review the investigations on the microstructural properties of metal-reinforced polymer composites. Scanning Electron Microscope (SEM) operating at a magnification range of 2,500× is typically used for examining the microstructure of the composites. Microstructural analysis reveals two key qualitative informations, dispersion and interfacial adhesion. It was observed from the review that flaky metal fillers will maximise dispersion and interfacial adhesion hence leading to improved mechanical, tribological, electrical, and thermal properties of the composites. Utilizing ternary metallic components helps to eliminate aggregation because the cohesion of metal particles is limited. It is important that future microstructural studies evaluate nano-sized fillers as compared to micro-sized ones. Also, it is important to quantitatively correlate the arrangement of the fillers to macro-scale properties and finite element analysis is an important tool that can help achieving this.

Numerical modeling of fiber orientation in multi-layer, isothermal material-extrusion big area additive manufacturing

Fiber orientation is a critical factor in determining the mechanical, electrical, and thermal properties of 3D-printed short-fiber polymer composites. However, the current numerical studies on predicting fiber orientation are limited to straight single-strand configurations, while the actual printed parts are often composed of complex multi-layer structures. To address this issue, we conducted numerical simulations of material extrusion in multi-layer big-area additive manufacturing without any post-deposition strand morphology modification mechanism. By examining the effects of material properties and printing conditions when extruding and depositing strands on a fixed substrate as well as previously deposited layers, it was possible to observe the complex interplay between multiple layers and its impact on fiber orientation. The work and methodology presented in this paper can be used to identify optimal extrusion-to-nozzle speed ratios, material rheology, fiber content, and fiber aspect ratio to achieve the desired performance and thermo/mechanical properties of additively manufactured parts. This work is an important contribution towards the manufacture of high-performance, short-fiber polymer composites as the presented methodology can enable engineers to precisely predict and tailor the fiber orientation in 3D printed parts.