Properties Of Polymer Nanocomposites Research Articles

Analyzing Tribological and Mechanical Properties of Polymer Nanocomposite for Brake Pad Applications - A Critical Review

A brake pad is an integral component of a vehicle's braking system, designed to impart controlled friction and, ultimately, assist in slowing or stopping a vehicle. Their constituents include binder, filler, abrasive, lubricant, and reinforcing fiber. Materials for brake pads must have excellent wear resistance, increased heat dissipation, a consistent coefficient of friction, low noise and vibration, durability, compatibility, minimal environmental impact, and cost-effectiveness. This paper aims to examine the various materials used in brake pad applications. They are composed of matrix, ceramic, and polymer composites, and are manufactured using various processes. In addition to mechanical and tribological testing, there are various methods for testing the mechanical and tribological properties of brake pads. Various instruments, such as SEM, TEM, AFM, and XRD, were surveyed in order to analyse the morphology and crystal structure of nanoscale brake pads. Various applications such as automobiles, railroads, and aerospace utilise brake pads. The study reveals that integrating nano-fillers into polymer composites significantly enhances the mechanical and tribological properties of automotive brake pads, offering a promising route toward more durable, efficient, and safer braking systems. Through this analysis, researchers will gain a deeper understanding of the materials used in brake pads and their adaptability for various applications.

Suppression of Segmental Chain Dynamics on a Particle's Surface in Well-Dispersed Polymer Nanocomposites.

The Rouse dynamics of polymer chains in model nanocomposite polyethylene oxide/silica nanoparticles (NPs) was investigated using quasielastic neutron scattering. The apparent Rouse rate of the polymer chains decreases as the particle loading increases. However, there is no evidence of an immobile segment population on the probed time scale of tens of ps. The slowing down of the dynamics is interpreted in terms of modified Rouse models for the chains in the NP interphase region. Thus, two chain populations, one bulk-like and the other characterized by a suppression of Rouse modes, are identified. The spatial extent of the interphase region is estimated to be about twice the adsorbed layer thickness, or ≈2 nm. These findings provide a detailed description of the suppression of the chain dynamics on the surface of NPs. These results are relevant insights on surface effects and confinement and provide a foundation for the understanding of the rheological properties of polymer nanocomposites with well-dispersed NPs.

Influence of MXene Composition on Triboelectricity of MXene-Alginate Nanocomposites.

MXenes are highly versatile and conductive 2D materials that can significantly enhance the triboelectric properties of polymer nanocomposites. Despite the growing interest in the tunable chemistry of MXenes for energy applications, the effect of their chemical composition on triboelectric power generation has yet to be thoroughly studied. Here, we investigate the impact of the chemical composition of MXenes, specifically the Ti3CNTx carbonitride vs the most studied carbide, Ti3C2Tx, on their interactions with sodium alginate biopolymer and, ultimately, the performance of a triboelectric nanogenerator (TENG) device. Our results show that adding 2 wt % of Ti3CNTx to alginate produces a synergistic effect that generates a higher triboelectric output than the Ti3C2Tx system. Spectroscopic analyses suggest that a higher oxygen and fluorine content on the surface of Ti3CNTx enhances hydrogen bonding with the alginate matrix, thereby increasing the surface charge density of the alginate oxygen atoms. This was further supported by Kelvin probe force microscopy, which revealed a more negative surface potential on Ti3CNTx-alginate, facilitating high charge transfer between the TENG electrodes. The optimized Ti3CNTx-alginate nanogenerator delivered an output of 670 V, 15 μA, and 0.28 W/m2. Additionally, we demonstrate that plasma oxidation of the MXene surface further enhances triboelectric performance. Due to the diverse surface terminations of MXene, we show that Ti3CNTx-alginate can function as either tribopositive or tribonegative material, depending on the counter-contacting material. Our findings provide a deeper understanding of how MXene composition affects their interaction with biopolymers and resulting tunable triboelectrification behavior. This opens up new avenues for developing flexible and efficient MXene-based TENG devices.

Mechanical and viscoelastic characterization of Al2O3 based polymer nanocomposites: An experimental and molecular dynamics simulation approach

Polymer nanocomposites (PNCs) being revolutionary materials, comprises polymer matrix phase and nanoparticles (NPs) phase. This study focuses on incorporating alumina (Al2O3) into poly-dimethyl siloxane (PDMS) matrix to analyze viscoelastic behavior and damping in response to dynamic mechanical loading. The experiments were performed using nano-DMA for comparing how Al2O3 reinforcement influences structural conformations and dynamic properties of PNCs. At 100 Hz, the storage modulus (E′) increases by 150%, 20%, and 74% for 1.0 wt% NPs with average particle sizes of 25 nm, 80 nm, and 200 nm, respectively. The significant changes in storage modulus and hardness values occur during variable frequencies (10 to 50 Hz) for 1.0 wt%, 9.0 wt%, and 7.0 wt% with reinforcements of 25 nm, 80 nm, and 200 nm, respectively. Adhesion factor and reinforcement efficiency factor highlight complementary effects of reinforcements at different frequencies. Further, an all-atom MD simulation method characterizes static and dynamic properties, predicting comprehensive dynamical and structural–property relationships. This quantifies damping capacity and reveals insights into how Al2O3 alters the material’s behavior. In summary, the study provides a precise comparative analysis of overall PNC performance, emphasizing the intrinsic effect on mechanical properties. It recognizes deformation mechanisms driving energy storage and dissipation for developing PNCs with enhanced mechanical performance.

Modeling the Interface Between Phases in Dense Polymer‐Carbon Black Nanoparticle Composites by Dielectric Spectroscopy: Where Are We Now and What are the Opportunities?

AbstractThe macroscopic properties of polymer nanocomposites (PNC) rely largely on the interphase between the polymer chains and the filler particles. One significant difficulty to solve this issue is to quantitatively model the structure‐property correlations due to the interfacial region in these complex materials. While dielectric spectroscopy (DS) measurements are routinely used to characterize the effective permittivity of filled polymers, fitting standard effective medium models and mixing equations to these data remains notoriously difficult to interpret. This is due to the absence of explicit reference to internal length scales characterizing the interfaces in the PNC. As an illustrative example, a two‐level homogenization framework is proposed which enables the extraction of useful information on the impact of a thin interphase confined on a nanometer length scale based on broadband DS data. This model leads to new ways of tuning the interphase so as to optimize the material's response to electric field, a situation relevant for electromagnetic shielding. This approach provides guidance on how to observe directly and experimentally the actual properties of the interface between the phases (as opposed to model‐based inference). Aside from its secure physical foundation in the theory of effective medium, a significant advantage of this approach is that a genetic algorithm (GA) technique applied to this physics‐based model enables the uniqueness of the fit parameters to be considered, as the GA method is robust in terms of finding globally optimum solutions, therefore placing confidence in non‐universal values of the percolation exponents. Recent work in physics‐informed machine learning indicates that the effective dielectric properties of PNC with many degrees of freedom due to their complex morphology can be described by considering only a few degrees of freedom describing the interface features between the phases in these composites.

The effects of interfacial layers on dielectric properties of an acrylic co-polymer containing polymer-grafted reduced graphene oxide

In this study, the influence of interfacial layers, in addition to other effective parameters, on the dielectric efficiency of polymer nanocomposites in the rubbery state is presented. For this purpose, reduced graphene oxide (rGO) was grafted by poly (butyl acrylate) chains (rGO-PBA) via surface-initiated atom transfer radical polymerization (SI-ATRP) and incorporated into an acrylic co-polymer matrix with the glass-transition temperature (Tg) well below room temperature. The rGO exhibited poor dispersion and uneven distribution in acrylic co-polymer, whereas polymer grafted-rGO showed excellent dispersion. The grafted chains can penetrate and form entropic interactions with the matrix chains, which results in a strong interfacial region. The immobilized interfacial layer was characterized by DSC and dielectric measurements. The dielectric measurements in different temperatures provided the means to evaluate the contribution of the interfacial layers on dielectric properties. The findings confirmed that there exists an optimum chain mobility in which the chain polarization shows a major contribution to the dielectric properties of polymer nanocomposites. Reduction of temperature to a certain degree exhibited more rise in the dielectric properties of polymer/rGO-PBA nanocomposites than pure matrix which can be correlated to the interfacial region.

Nanocomposite Material Based on Polyvinyl Alcohol Modified with Carbon Nanotubes: Mechanism of Formation and Electronic Energy Structure

The physical chemistry of surface phenomena in polymers is an important issue when studying the interaction of polymers with solid surfaces. This is due to the fact that most of the modern polymer materials are heterogeneous systems with highly developed phase separation surfaces. An example of such materials can be reinforced plastic, filled thermoplastics, reinforced rubber, paint coatings, etc. Polymer adsorption at the boundary of the phase separation process in solids plays an important role in the reinforcing effect of fillers, adhesion, gluing and obtaining composite materials with high strength properties. Compositions based on polyvinyl alcohol (PVA) modified with carbon nanotubes (CNTs) can be used as an interesting and informative system for studying the structure and properties of polymer nanocomposites, especially in a highly oriented state. PVA has one of the simplest chemical structure among the polymers, containing a functional (hydroxyl) group capable of participating in interphase interactions. In turn, carbon nanotubes with unique strength properties are currently products of industrial production, which makes it possible to control and modify their properties. To prove the possibility of creating new composite materials with improved strength characteristics, the mechanisms of interaction between PVA and CNTs are studied by modeling the adsorption processes of a polymer fragment on the outer surface of single-layer carbon nanotubes of different chirality, performed within the framework of the modern DFT calculation method. The main adsorption characteristics of the process and the features of the electron energy structure of the resulting composite systems are determined.

Application-Driven High-Thermal-Conductivity Polymer Nanocomposites.

Polymer nanocomposites combine the merits of polymer matrices and the unusual effects of nanoscale reinforcements and have been recognized as important members of the material family. Being a fundamental material property, thermal conductivity directly affects the molding and processing of materials as well as the design and performance of devices and systems. Polymer nanocomposites have been used in numerous industrial fields; thus, high demands are placed on the thermal conductivity feature of polymer nanocomposites. In this Perspective, we first provide roadmaps for the development of polymer nanocomposites with isotropic, in-plane, and through-plane high thermal conductivities, demonstrating the great effect of nanoscale reinforcements on thermal conductivity enhancement of polymer nanocomposites. Then the significance of the thermal conductivity of polymer nanocomposites in different application fields, including wearable electronics, thermal interface materials, battery thermal management, dielectric capacitors, electrical equipment, solar thermal energy storage, biomedical applications, carbon dioxide capture, and radiative cooling, are highlighted. In future research, we should continue to focus on methods that can further improve the thermal conductivity of polymer nanocomposites. On the other hand, we should pay more attention to the synergistic improvement of the thermal conductivity and other properties of polymer nanocomposites. Emerging polymer nanocomposites with high thermal conductivity should be based on application-oriented research.

Enhanced dielectric properties of poly(vinylidene fluoride) matrix nanocomposites incorporated with one–dimensional structure of titanate nanotubes

The dielectric properties of polymer nanocomposites based on a poly(vinylidene fluoride) (PVDF) matrix, filled with a one–dimensional nanostructure of titanate nanotubes (TNTs), were investigated. These studies demonstrated significant improvements in the energy storage capability of the application. The TNTs were synthesized through an alkali hydrothermal treatment method at 130 °C for 24 h, using a 10 M NaOH solution. The TNTs exhibited a large dielectric permittivity of approximately 1.2 × 104 with a low loss tangent of approximately 0.12 at 1 kHz and 25 °C. TNTs/PVDF polymer nanocomposites were studied and fabricated using liquid phase–assisted dispersion and hot–pressing methods. By introducing TNTs into the PVDF polymer, both the dielectric permittivity and loss tangent increased. Notably, the polymer nanocomposite containing 50 wt. % TNTs exhibited a dielectric permittivity of 5.3 × 103 at 1 kHz, which is ∼530 times greater than that of pure PVDF (10.78), while the loss tangent remained at 0.572. The low–frequency dielectric permittivity increased with an increase in relative humidity from 50 to 95 % due to enhanced interfacial polarization at the surface and electrode interface. However, at frequencies greater than 1 kHz, the dielectric permittivity was independent of relative humidity. The improvement in the enhanced dielectric permittivity of polymer–based nanocomposites with incorporated TNTs was ascribed to these factors.

Optical, conductivity, dielectric, and magnetic properties of polymer nanocomposite based on PAM/cs matrix and ZnFe2O4 NPs for use in magneto-electronic and energy storage capacitor devices

In this study, a cast synthesis approach was used to create flexible nanocomposite films made of polyacrylamide (PAM), chitosan (Cs), and zinc ferrite nanoparticles (ZnFe2O4 NPs). XRD analysis was used to examine the composite structure. They demonstrated the effective interaction between ZnFe2O4 NPs and PAM/Cs blend. As the concentration of nanomaterial in the host polymer matrix grew, it was observed that the PAM/Cs matrix's direct and indirect energy band gaps decreased while its absorbance of ultraviolet–visible radiations increased. The nanocomposite's AC conductivity was significantly higher than that of the blend, and 2.5 wt percent of the nanocomposite showed the highest electrical conductivity. It was observed that as frequency raised, the ε′ and ε″ declined though the concentration of nanoparticles enhanced these characteristics. Because of the high dielectric permittivity of ZnFe2O4, the values of ε′ and ε″ raised as ZnFe2O4 were higher. The outcome of the vibrating sample magnetometer (VSM) demonstrated the ferromagnetic property of the produced nanocomposites. Furthermore, the VSM study shows that as the nanoparticles content increases, the PAM/Cs/ZnFe2O4 nanocomposites' Ms, Hc, and Mr also increase. These PAM/Cs/ZnFe2O4 films were shown by the experimental results to be promising candidates for bandgap-regulated materials, electromagnetic interference shielders, frequency tunable nanodielectric, and flexible dielectric substrates for future microelectronic, optoelectronic technologies, and capacitive energy storage.

Polymer nanocomposite dielectrics for capacitive energy storage.

Owing to their excellent discharged energy density over a broad temperature range, polymer nanocomposites offer immense potential as dielectric materials in advanced electrical and electronic systems, such as intelligent electric vehicles, smart grids and renewable energy generation. In recent years, various nanoscale approaches have been developed to induce appreciable enhancement in discharged energy density. In this Review, we discuss the state-of-the-art polymer nanocomposites with improved energy density from three key aspects: dipole activity, breakdown resistance and heat tolerance. We also describe the physical properties of polymer nanocomposite interfaces, showing how the electrical, mechanical and thermal characteristics impact energy storage performances and how they are interrelated. Further, we discuss multi-level nanotechnologies including monomer design, crosslinking, polymer blending, nanofiller incorporation and multilayer fabrication. We conclude by presenting the current challenges and future opportunities in this field.

Synergistic effect of carbon nanotube/graphene nanoplatelet hybrids on the elastic and viscoelastic properties of polymer nanocomposites: finite element micromechanical modeling

Synergistic effect of carbon nanotube/graphene nanoplatelet hybrids on the elastic and viscoelastic properties of polymer nanocomposites: finite element micromechanical modeling

Comprehensive 3-D homogenization approach for predicting mechanical properties and creep behavior of polymer nanocomposites reinforced with graphene nanoplatelets

The aim of this study is to provide a comprehensive 3-D homogenization approach based on the high-fidelity generalized method of cells method to predict the mechanical properties and creep behavior of polymer nanocomposite reinforced with graphene nanoplatelets. Several fundamental experimental aspects including the volume fraction, size, and random orientation of graphene nanoplatelets, the interphase region, and the aggregation state of nanofillers of graphene are taken into account. The present study introduces two novel perspectives. At first, the aggregation of graphene nanoplatelets is formulated as dependent on volume fraction. Then the size of graphene is formulated as an important factor affecting the interphase region and the mechanical properties of polymer nanocomposite. Micromechanical tests conducted using the proposed method illustrate the good agreement with experimental data. The results of the parametric study on different experimental aspects revealed important findings. (i) For a specific value of graphene nanoplatelet volume fraction, the mechanical properties of polymer nanocomposite are at the best state. By increasing the graphene content beyond the specified graphene content value, the effective properties of graphene are decreased. (ii) The size of graphene nanoplatelets and the characteristics of the graphene/polymer interphase region have a direct effect on the properties of the nanocomposite.

ОГЛЯД МЕХАНІЧНИХ ВЛАСТИВОСТЕЙ НАНОКОМПОЗИТІВ НА ПРЕДМЕТ ЇХ ВИКОРИСТАННЯ У ПАРАХ КОВЗАННЯ МЕХАНІЗМІВ АВІАТЕХНІКИ

The object of the review is polymer nanocomposites (PNC), which are used to increase the wear resistance and durability of mechanical contacting surfaces of parts of machines and mechanisms. The goal is to analyze the production and mechanical properties of PNC when they are used in aircraft and helicopter structural units operating in sliding pairs with a large resource. The analysis of existing research and publications on the use of PNC showed that the use of nanocomposites with a plastic base can be recommended for the manufacture of tribological pairs of aircraft parts. It was established that most authors among the considered nanoadditives give preference to nanodiamonds with a concentration in the range of 1...3%, which, in comparison with all other nanomaterials, give a consistently positive result and also have good environmental indicators.It was found that for parts of friction pairs it is possible to provide a friction coefficient of about 0.1 due to the use of composite polymers with ND. The following results were obtained. The performed review will allow to create a regulatory base of nanomaterials, necessary for solving structural and technological solutions in sliding pairs of aviation equipment. According to the analysis of the existing current and actual PNC and their preparation, it was established that a friction coefficient of 0.12 can be ensured for the titanium nanocomposite Ti/ND with a content of 0.35% of ND. It is shown that the galvanic application of nanocoatings on steel with a concentration of nanodiamonds in the solution of 8.0 g/l and a current density of 3.0 A/dm2 can provide the hardness of the composite coating with a maximum value of 5.302 GPa and an average grain size of 4 nm. The scientific novelty of the obtained results is as follows: the production technologies and main mechanical properties of PNC when used in sliding pairs of aircraft parts are analyzed. It was found that the existing publications do not provide enough information about the important parameters of the obtained materials, such as heat resistance, moisture resistance, environmental friendliness, and others. Conclusions. It is recommended to test ND with a concentration in the range of 1...3% on tribological parts of aircraft, as well as in sliding pairs with a long life. However, despite the unique mechanical properties of nanocomposites, the regulatory framework for the design of sliding pairs requires additional research and experiments. The given materials can be useful in carrying out theoretical and experimental studies on extending the resource, operation and repair of aircraft and helicopter parts.

Insights into nanomechanical and nanotribological characterization of cross-linked polymer nanocomposites via molecular dynamics simulation

Polymer nanocomposites (PNCs) representing the cutting-edge domain of research have been exploited through indentation with experimentation and simulation. However, comprehending the underlying deformation mechanism via indentation in PNCs is still an open question. The present study emphasis on the influence of incorporating different sizes of nanoparticles (NPs) with varied volume fraction to regulate and improve mechanical and tribological properties of PNCs through molecular dynamics (MD) simulations. The coarse-grained MD simulations for nanoindentation and nanoscratching of crosslinked polymer network without and with NPs are performed. The identification of static and dynamic properties reveals the domains of dispersion and agglomeration with structural conformations in the PNCs. The NPs act as promising reinforcements that significantly strengthen the polymer system through improvement in mechanical and tribological properties. Further the analysis of curing percentage and bond breakage play vital role in locating stress induced sites during indentation. From MD simulations, the prominent improvement in deformation resistance is shown with particles exhibiting least radius of 1.5σ and 2.5σ which enhances with increase in volume fraction of NPs. The observations evoke the fact that presence of NPs reduce coefficient of friction (cof) and diminishes the resistance against scratch which generates higher shear strain in polymer chains. The main aim of this study is to provide design rule for incorporation of NPs coordinated towards tuning mechanical and tribological performance of PNCs. Additionally, insights into the deformation and nanoscratching mechanisms are highlighted providing directions to confer multi-functionalities to advanced PNCs.

Strain-Sensitive Properties of Polymer Nanocomposites Based on Island Films

Strain-Sensitive Properties of Polymer Nanocomposites Based on Island Films

The Influence of Aging on the Structure and Properties of Composite Materials Based on Polyurethane and Silver Nanoparticles

The aging processes and their influence on structure, thermophysical and antimicrobial properties of polymer nanocomposites based on segmented polyurethane and silver nanoparticles were studied. It was established that an increase in the intensity of intermolecular interactions of polyurethane occurred regardless of the concentration of silver in the silver nanoparticles due to a change in the packing of macromolecules. It was shown that in the process of aging of composites, the effective size of crystallites of polymer matrix decreases and varies in the range of 1.35–1.50 nm. The most pronounced effect of aging is manifested on the melting temperatures of the crystalline phase of polyurethane and the degree of crystallinity. It was found that polyurethane–silver nanoparticle composites exhibit a very high inhibitory capacity against Staphylococcus aureus, Escherichia coli, and Candida albicans. It is shown that aging processes do not affect the antimicrobial characteristics of the studied materials, which indicates their stability. Due to their unique characteristics, synthesized nanocomposite films can be promising for use as antimicrobial coatings in various applications.

Modulating polarization and carrier migration characteristics via constructing sandwich-structured heterojunction interfaces for achieving excellent high-temperature energy storage properties in polymer nanocomposites

Dielectric polymer nanocomposites are ideal choices for electrostatic energy storage due to their high power density and reliability, but they cannot operate efficiently at high temperature. To solve this issue, herein, we designed and developed sandwich-structured montmorillonite (MMT)/polyetherimide (PEI)-(Pb,La)(Zr,Sn,Ti)O3 (PLZST) antiferroelectrics (AFEs)@dopamine (DA)-MMT/PEI nanocomposites. On one hand, compared to current wide-band gap fillers, i.e., TiO2, Al2O3, ZrO2, and MgO, two-dimensional MMT nanosheets possess unique electrically insulating performances along the thickness direction, and thus can effectively stop charges injecting and migrating, causing low conduction loss, and large breakdown strength (Eb). On the other hand, PLZST AFEs with orthorhombic structure can exhibit high maximum electric displacement (Dmax) and small remnant electric displacement (Dr) at high temperature, which is beneficial for achieving large Dmax-Dr in the nanocomposites. In addition, large dielectric constant differences between MMT/PEI and PLZST@DA/PEI layers can inhibit electrical tree growth, resulting in further raised Eb. Finite element simulations on electrical tree evolving confirm experimental breakdown results. The sandwich-structured nanocomposite displays impressive high-temperature (150 °C) capacitive performances possessing meanwhile a high Eb of 5265.9 kV/cm, large discharged energy density (Ue) of 7.1 J/cm3, being about 6 times that of the commercial biaxially oriented polypropylene, and large charge-discharge efficiency (η) of 81.6 %, which exceeds obviously latest polymer and polymer composites in terms of overall energy storage performances. More encouragingly, it displays an ultrahigh power density of 15.63 MW/cm3 and ultrafast discharge rate of 19.2 ns at 150 °C, indicate its excellent application potential in high-temperature pulse power systems.

Effect of melt blending processing on mechanical properties of polymer nanocomposites: a review

Effect of melt blending processing on mechanical properties of polymer nanocomposites: a review

Unraveling bilayer interfacial features and their effects in polar polymer nanocomposites

Polymer nanocomposites with nanoparticles dispersed in polymer matrices have attracted extensive attention due to their significantly improved overall performance, in which the nanoparticle-polymer interface plays a key role. Understanding the structures and properties of the interfacial region, however, remains a major challenge for polymer nanocomposites. Here, we directly observe the presence of two interfacial polymer layers around a nanoparticle in polar polymers, i.e., an inner bound polar layer (~10 nm thick) with aligned dipoles and an outer polar layer (over 100 nm thick) with randomly orientated dipoles. Our results reveal that the impacts of the local nanoparticle surface potential and interparticle distance on molecular dipoles induce interfacial polymer layers with different polar molecular conformations from the bulk polymer. The bilayer interfacial features lead to an exceptional enhancement in polarity-related properties of polymer nanocomposites at ultralow nanoparticle loadings. By maximizing the contribution of inner bound polar layer via a nanolamination design, we achieve an ultrahigh dielectric energy storage density of 86 J/cm3, far superior to state-of-the-art polymers and nanocomposites.