A comparative study of PMMA/PEG polymer nanocomposites doped with different oxides nanoparticles for potential optoelectronic applications

PMMA/PEG and PMMA/PEG doped with SiO2, TiO2, and Al2O3 were fabricated using the solution-casting technique. The composites were characterized by X-ray diffraction and scanning electron microscopy (FE-SEM), which revealed that the amorphous nature of PMMA/PEG blend doped with Al2O3 was hindered by the crystalline nature of those doped with SiO2 and TiO2. The absorption of PMMA/PEG blend doped with Al2O3 is higher, band gap energies were decreased from 4.90 eV for PMMA/PEG blend to 4.03 eV, 3.09 eV, and 2.09 eV for SiO2, TiO2, and Al2O3 doped PMMA/PEG blend, respectively. The dielectric constant, ε' has a high value (2 × 104) for samples PMMA/PEG and SiO2/PMMA/PEG. While dielectric lossε ″ -values decreased to < 100 for TiO2/PMMA/PEG and Al2O3/PMMA/PEG. Further, the fabricated composite SiO2/PMMA/PEG led to improvement the optical and dielectric properties compared with PMMA/PEG for optoelectronic such as manufacturing of optical fiber cables application. The results show TiO2/PMMA/PEG and Al2O3/PMMA/PEG are multifunctional can be used as low-permittivity nanodielectric and substrates to design the next generation of flexible electronic devices.

Influence of Pressing Temperatures on Physical-Mechanical Properties of Wood Particleboards Made with Urea-Formaldehyde Adhesive Containing Al2O3 and CuO Nanoparticles

Particleboards have gained attention in the global market. Understanding their physical-mechanical behavior in the current technological context is essential due to adhesive polymerization, which depends on variables such as pressing time and temperature. Today, the use of nanoparticles has become a plausible option for improving the properties of polymers used in wood-based composites. This study evaluates the influences of the addition of non-commercial 0.5% aluminum oxide (Al2O3) and aluminum oxide copper (CuO) nanoparticles using a greener route with a lower environmental impact obtaining a urea-formaldehyde (UF)-based polymeric adhesive to manufacture particle composites of Eucalyptus urophylla var. grandis wood. Regarding characterizations, the resin properties analyzed were viscosity, gel time, and pH, as well as panel properties, including density, moisture content, thickness swelling, modulus of elasticity, modulus of rupture, and thermal conductivity. The results were compared with scientific publications and standards. The addition of nanoparticles interfered with viscosity, and all treatments indicated a basic pH. It was not possible to determine the gel time after 10 min. Nanoparticles added to the polymers in the internal layer did not cause an improvement in the swelling properties in terms of thickness, with no significant statistical difference for density and moisture content. The increase from 150 °C to 180 °C may have caused an improvement in all physical-mechanical properties, indicating that the higher temperature positively influenced the polymerization of the formaldehyde-based adhesive. Therefore, the additions of both nanoparticles (0.5% in each condition) led to a limitation in the material influence with respect to physical-mechanical performance.

Atomistic to Mesoscopic Modelling of Thermophysical Properties of Graphene-Reinforced Epoxy Nanocomposites

This research addresses the need for a multiscale model for the determination of the thermophysical properties of nanofiller-enhanced thermoset polymer composites. Specifically, we analyzed the thermophysical properties of an epoxy resin containing bisphenol-A diglyceryl ether (DGEBA) as an epoxy monomer and dicyandiamide (DICY) and diethylene triamine (DETA) as cross-linking agents. The cross-linking process occurs at the atomistic scale through the formation of bonds among the reactive particles within the epoxy and hardener molecules. To derive the interatomic coarse-grained potential for the mesoscopic model and match the density of the material studied through atomic simulations, we employed the iterative Boltzmann inversion method. The newly developed coarse-grained molecular dynamics model effectively reproduces various thermophysical properties of the DGEBA-DICY-DETA resin system. Furthermore, we simulated nanocomposites made of the considered epoxy additivated with graphene nanofillers at the mesoscopic level and verified them against continuum approaches. Our results demonstrate that a moderate amount of nanofillers (up to 2 wt.%) increases the elastic modulus and thermal conductivity of the epoxy resin while decreasing the Poisson's ratio. For the first time, we present a coarse-grained model of DGEBA-DICY-DETA/graphene materials, which can facilitate the design and development of composites with tunable thermophysical properties for a potentially wide range of applications, e.g., automotive, aerospace, biomedical, or energy ones.

Effects of graphene, alumina, and their hybrid on dynamic mechanical behavior of epoxy-based nanocomposites

Graphene has excellent mechanical and thermal properties, while alumina has inexpensive and strong thermal stability, making it ideal for electronic packaging applications. The current work examines the effects of modest loadings of reduced graphene oxide (rGO), alumina (Ala), and their hybrids on the dynamic mechanical characteristics and thermal transitions of epoxy-based nanocomposites. The rGO was made using a modified Hummers’ method. Alumina nanoparticles were used as received. Various epoxy nanocomposite samples with 1 wt% of rGO, 1 wt% of Ala, and 0.5 wt% each of rGO and Ala were created. Then, Raman spectroscopy, XRD, FTIR, XPS, TEM, AFM, and SEM were used to analyze the fillers and their hybrid and epoxy-based nanocomposites. Dynamic mechanical analysis was used to examine the hybrid epoxy-based nanocomposites’ dynamic mechanical behavior. It has been demonstrated that different epoxy nanocomposites with 1 wt% Ala and 1 wt% rGO have higher elastic moduli than those with 0.5 wt% rGO and 0.5 wt% Ala. The rGO-Ala hybrid nanocomposites, on the other hand, exhibit moderate damping and glass transition temperatures. The reason for that may be because Ala filler increases the contact area between the rGO sheets and serves as a bridge between the two fillers, decreasing the resistance to deformation. This may enhance the possibility that these stress concentrations will weaken the composites.

Simultaneously Enhanced Thermal Conductivity and Dielectric Breakdown Strength in Sandwich AlN/Epoxy Composites

Polymer-based composites with high thermal conductivity and dielectric breakdown strength have gained increasing attention due to their significant application potential in both power electronic devices and power equipment. In this study, we successfully prepared novel sandwich AlN/epoxy composites with various layer thicknesses, showing simultaneously and remarkably enhanced dielectric breakdown strength and thermal conductivity. The most optimized sandwich composite, with an outer layer thickness of 120 μm and an inner layer thickness of 60 μm (abbreviated as 120-60) exhibits a high through-plane thermal conductivity of 0.754 W/(m·K) (4.1 times of epoxy) and has a dielectric breakdown strength of 69.7 kV/mm, 8.1% higher compared to that of epoxy. The sandwich composites also have higher in-plane thermal conductivity (1.88 W/(m·K) for 120-60) based on the novel parallel models. The sandwich composites with desirable thermal and electrical properties are very promising for application in power electronic devices and power equipment.

Hyperbranched aromatic polyamide modified magnetic nanoparticles for the extraction of benzoylurea insecticides

Herein, a novel hyperbranched aromatic polyamide-coated magnetic sorbent was prepared by in situ polymerization on the surface of amino-functionalized Fe₃ O₄ nanoparticles. The magnetic sorbent was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, elemental analysis, Brunauer-Emmett-Teller measurement, and X-ray photoelectron spectroscopy, etc. The new magnetic sorbent was used in the magnetic solid-phase extraction for the detection of seven benzoylurea insecticides. Under optimum conditions, low method detection limits (0.56-1.20 ng/mL), acceptable coefficient of determination (0.9967-0.9996), wide linear ranges (2.5-500.0 ng/mL), and good repeatability (intraday: 2.0-7.3%; interday: 1.9-9.2%) were achieved. The magnetic solid-phase extraction method based on the new magnetic sorbent showed good reliability in the analysis of seven benzoylurea insecticides in real water samples, as the relative recoveries were in the range from 80.1 to 116.3% with satisfactory RSDs (0.1-9.8%). By means of density functional theory and semiempirical quantum mechanical, the binding configuration and interaction energy of hyperbranched aromatic polyamide and benzoylurea insecticides were calculated. The result of theoretical calculation revealed that the adsorption of benzoylurea insecticides by hyperbranched aromatic polyamide was derived from hydrogen bonding and π-π stacking. The contribution of π-π stacking was greater than that of hydrogen bond, which was confirmed by energy decomposition analysis.

Curing Behavior, Rheological, and Thermal Properties of DGEBA Modified with Synthesized BPA/PEG Hyperbranched Epoxy after Their Photo-Initiated Cationic Polymerization

This paper investigates the photo-initiated cationic polymerization of diglycidyl ether of bisphenol A (DGEBA) modified with bisphenol A (BPA)/polyethylene glycol (PEG) hyperbranched epoxy resin. The relationship between curing behavior, rheological, and thermal properties of the modified DGEBA is investigated using photo-differential scanning calorimetry (DSC) and photo-rheometer techniques. It is seen that the addition of the hyperbranched epoxy resin can increase UV conversion (αUV) and reduce gelation time (tgel). After photo-initiation polymerization (dark reaction) occurred, a second exothermic peak in the DSC thermogram takes place: namely, the occurrence of curing reaction owing to the activated monomer (AM) mechanism. Consequently, the glass transition temperature decreased, and at the same time, UV intensity increased which was due to the molecular weight between crosslinking points (Mc). Furthermore, the radius of gyration (Rg) of the network segment is determined via small-angle X-ray scattering (SAXS). It is noted that the higher the Mc, the larger the radius of gyration proves to be, resulting in low glass transition temperature.

Efficient Thermal Transport Highway Construction Within Epoxy Matrix via Hybrid Carbon Fibers and Alumina Particles

Polymer composites with excellent thermal conductivity and superior mechanical strength are in high demand in the electrical engineering systems. However, achieving superior thermal conductivity and mechanical properties simultaneously at high loading of fillers will still be a challenging issue. In this work, a facile method was proposed to prepare the epoxy composite with carbon fibers (CFs) and alumina (Al₂O₃). This CF and Al₂O₃ hybrid structure can effectively reduce the interfacial thermal resistance between the matrix and the CFs. The thermal conductivity of epoxy composite with 6.4 wt % CFs and 74 wt % Al₂O₃ hybrid filler reaches 3.84 W/(m K), which is increasing by 2096% compared with that of pure epoxy. Meanwhile, the epoxy composite still retains outstanding thermal stability and mechanical performance at high filler loading. A cost-effective avenue to prepare highly thermally conductive and superior mechanical properties of polymer-based composites may enable some prospective application in advanced thermal management.

Synthesis, Thermal Properties and Curing Kinetics of Hyperbranched BPA/PEG Epoxy Resin

The hyperbranched epoxy resins (HBE) composed of bisphenol A (BPA) and polyethylene glycol (PEG) as reactants and pentaerythritol as branching point were successfully synthesized via A₂ + B₄ polycondensation reaction at various BPA/PEG ratios. The ¹³C NMR spectra revealed that the synthesized HBE mainly had a dendritic structure as confirmed by the high degree of branching (DB). The addition of PEG in the resin enhanced degree of branching (DB) (from 0.82 to 0.90), epoxy equivalent weight (EEW) (from 697 g eq⁻¹ to 468 g eq⁻¹) as well as curing reaction. Adding 5–10 wt.% PEG in the resin decreased the onset and peak curing temperatures and glass transition temperature; however, adding 15 wt.% PEG in the resin have increased these thermal properties due to the lowest EEW. The curing kinetics were evaluated by fitting the experimental data of the curing behavior of all resins with the Šesták–Berggren equation. The activation energy increased with the increase of PEG in the resins due to HBE’s steric hindrance, whereas the activation energy of HBE15P decreased due to a large amount of equivalent active epoxy group per mass sample. The curing behavior and thermal properties of obtained hyperbranched BPA/PEG epoxy resin would be suitable for using in electronics application.

Enhanced Thermal Conductivity of Epoxy Composites Filled with 2D Transition Metal Carbides (MXenes) with Ultralow Loading

With the development of electronic devices such as integrated circuits toward the continual increase in power density and consumption, the efficient heat dissipation and low thermal expansion of materials become one of the most important issue. However, conventional polymers have the problem of poor thermal dissipation performance, which hinder application for electronic devices. In this work, the two-dimensional material, MXene (Ti₃C₂), is used as the reinforcement additive to optimize the thermal properties of polymers. We reported the preparation of multilayer Ti₃C₂ MXene by HF etching method and obtained few-layer Ti₃C₂ MXene by simple ultrasonication. Meanwhile, Ti₃C₂/epoxy composites were prepared by a solution blending method. The results show that the thermal properties of the composites are improved in comparison with the neat epoxy. Thermal conductivity value (0.587 W/mK) of epoxy composite with only 1.0 wt% Ti₃C₂ MXene fillers, is increased by 141.3% compared with that of neat epoxy. In addition, the composite presents an increased glass transition temperature, high thermal stability and lower coefficient of thermal expansion. This work is of great significance for the research of high-performance composite materials.

Highly Thermally Conductive Composite Films Based on Nanofibrillated Cellulose in Situ Coated with a Small Amount of Silver Nanoparticles

In this paper, a freestanding flexible nanofibrillated cellulose (NFC)/silver (Ag) composite film with high thermal conductivity (TC) was prepared using the NFC that was in situ coated with a small amount of Ag nanoparticles through mussel-inspired chemistry of dopamine. The results demonstrated that Ag nanoparticles were homogeneously coated on the surface of NFC nanofibers and their incorporation had little influence on the film-forming ability of NFC. The NFC decorated with Ag nanoparticles could easily form thermally conductive pathways in the composite films, and the resultant films containing only 2.0 vol % of Ag showed a high in-plane TC value of 6.0 W/(m·K), which was 4 times that of pure NFC film. Moreover, the composite films exhibited relatively high strength and flexibility. The highly thermally conductive NFC/Ag composite films possess potential applications as lateral heat spreaders in flexible electronic equipment.

Significantly Enhanced Dielectric Performances and High Thermal Conductivity in Poly(vinylidene fluoride)-Based Composites Enabled by SiC@SiO2 Core-Shell Whiskers Alignment

Design of composites with ordered fillers arrangement results in anisotropic performances with greatly enhanced properties along a specific direction, which is a powerful tool to optimize physical properties of composites. Well-aligned core-shell SiC@SiO₂ whiskers in poly(vinylidene fluoride) (PVDF) matrix has been achieved via a modified spinning approach. Because of the high aspect ratio of SiC whiskers, strong anisotropy and significant enhancement in dielectric constant were observed with permittivity 854 along the parallel direction versus 71 along the perpendicular direction at 20 vol % SiC@SiO₂ loading, while little increase in dielectric loss was found due to the highly insulating SiO₂ shell. The anisotropic dielectric behavior of the composite is perfectly understood macroscopically to have originated from anisotropic intensity of interfacial polarization based on an equivalent circuit model of two parallel RC circuits connected in series. Furthermore, finite element simulations on the three-dimensional distribution of local electric field, polarization, and leakage current density in oriented SiC@SiO₂/PVDF composites under different applied electrical field directions unambiguously revealed that aligned core-shell SiC@SiO₂ whiskers with a high aspect ratio significantly improved dielectric performances. Importantly, the thermal conductivity of the composite was synchronously enhanced over 7 times as compared to that of PVDF matrix along the parallel direction at 20 vol % SiC@SiO₂ whiskers loading. This study highlights an effective strategy to achieve excellent comprehensive properties for high-k dielectrics.

Functional Aromatic Polyamides

We describe herein the state of the art following the last 8 years of research into aromatic polyamides, wholly aromatic polyamides or aramids. These polymers belong to the family of high performance materials because of their exceptional thermal and mechanical behavior. Commercially, they have been transformed into fibers mainly for production of advanced composites, paper, and cut and fire protective garments. Huge research efforts have been carried out to take advantage of the mentioned characteristics in advanced fields related to transport applications, optically active materials, electroactive materials, smart materials, or materials with even better mechanical and thermal behavior.

Development and characterization of tetraglycidyl epoxy reinforced inorganic hybrid nanomaterials for high performance applications

In the present work, tetraglycidyl 1,4′-bis (4-amine-phenoxy) benzene (TGBAPB) epoxy resin has been developed using 1,4′-bis (4-amine-phenoxy) benzene and epichlorohydrin. The amine-functionalized nanoalumina (F-nAl) was prepared using 3-aminopropyltriethoxysilane. TGBAPB epoxy resin was further reinforced with different weight percentages (1–5 wt%) of F-nAl and were cured with 4,4′-diaminodiphenylmethane. Thermal and thermomechanical behavior of TGBAPB epoxy matrix and nanocomposites were studied using thermogravimetric and differential scanning calorimetric analyses. The surface morphology of epoxy nanocomposites was examined using transmission electron microscopic, scanning electron microscopic, and atomic force microscopic studies respectively.

Data obtained from mechanical and thermal studies/analysis indicate that these nanocomposites could be used as high-performance materials for varied advanced industrial and engineering applications.

Preparation and property of epoxy resins-penetrated aligned carbon nanotube bundle hybrid microcapsules for self-healing polymers

The epoxy resins-penetrated aligned carbon nanotube bundle (ACNTsB) hybrid system (epoxy@ACNTsB) was prepared by soaking ACNTsB in the acetone solution of epoxy resins. Epoxy@ACNTsB was encapsulated in aqueous solution containing an amine curing agent to prepare hybrid microcapsules (MCs). The structure and morphology of MCs were characterized by Fourier transform infrared spectroscopy, scanning electronic microscopy, transmission electron microscopy, and laser scanning confocal microscopy. The thermal properties of MCs were carried out by differential scanning calorimetry and thermogravimetric analysis. The solvent resistance of MCs in acetone was also investigated. The results show that MCs exhibit high initial decomposition of temperatures (266°C). The content of epoxy resin in MCs is about 74% and the polymer film thickness of MCs is from 1 to 2 μm. MCs show high thermal and chemical stability below 200°C and excellent solvent resistance. MCs embedded in cyanate ester (CE) resins can significantly toughen the matrix. The fracture MCs can release the epoxy resins under heating condition, and the released epoxy resins can react with the reactive –OCN group/triazine rings in the CE matrix to rebond the crack surfaces. When the temperature schedule of 100°C/1 h + 200°C/2 h is applied, 10–15 wt% MCs can recover from 82.7% to 99.8% of the original fracture toughness of CE matrix.

Enhanced thermal conductivity for poly(vinylidene fluoride) composites with nano-carbon fillers

The GS filler provides stronger enhancement of the thermal conductivity (up to 2.06 W m⁻¹ K⁻¹) in comparison with SF and CNTs, which is approximately 10-fold enhancement in comparison to that of the neat PVDF.

Effects of h-BN on the thermal and mechanical properties of PBT/PC/ABS blend based composites

H-BNMPs were shown to have an obvious effect on the thermal conductivity of the blend. The addition of h-BN hybrids enhanced the mechanical properties of composites with remarkably improvement of the thermal conductivity.

Ultralow dielectric, high performing hyperbranched epoxy thermosets: synthesis, characterization and property evaluation

The present work addresses the major drawbacks, such as low toughness character and high dielectric constant, of conventional epoxy thermosets through macromolecular engineering.

Enhanced thermal properties in a hybrid graphene–alumina filler for epoxy composites

The inclusion of hybrid LCPBI/RGO and Al₂O₃-APS fillers into a polymer matrix with formation of composites has proven to be an efficient way to improve thermal properties of the composites.

Effect of Modifying Prosthetic Socket Base Materials by Adding Nanodiamonds

The curing process of prosthetic socket base materials requires attention owing to a series of associated problems that are yet to be addressed and solved. However, to date, few relevant studies have been reported. In this paper, nanodiamonds modified with a silane coupling agent were dispersed into a prosthetic socket base material, and the performance of the modified base materials was investigated. Adding a predetermined amount of nanodiamonds to the prosthetic socket base material increased the glass transition temperature, improved the mechanical properties of the cured base material, and reduced the influence of the volatile gas formed during the curing process on the environment. With increasing nanodiamond contents, the glass transition temperature increased and the mechanical properties improved slightly. Owing to the high thermal conductivity of the nanodiamonds, the localized heat, as a result of the curing process, could be dissipated and released. Thus, adding nanodiamonds led to a more uniform temperature field forming in the curing system. This improved the curing process and reduced the formation of volatile monomers, thereby decreasing the adverse impact of the generated volatile gases on the environment. All of these provide a potential strategy for modifying prosthetic socket base materials.

Studies on mechanical, thermal and dynamic mechanical properties of functionalized nanoalumina reinforced sulphone ether linked tetraglycidyl epoxy nanocomposites

The objective of the present work is to synthesize 1,4′-bis (4-amine-phenoxy) sulphone benzene epoxy resin (TGBAPSB) via 1,4′-bis (4-amine-phenoxy) sulphone benzene (BAPSB) and epichlorohydrin in order to obtain tetra functional epoxy with improved properties.

Nano–micro structure of functionalized boron nitride and aluminum oxide for epoxy composites with enhanced thermal conductivity and breakdown strength

Nano-micro structure of modified 2-D and 0-D ceramic fillers is designed for epoxy with high thermal conductivity and breakdown strength.

Core-shell structured hyperbranched aromatic polyamide/BaTiO3 hybrid filler for poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) nanocomposites with the dielectric constant comparable to that of percolative composites

Polymer nanocomposites with the dielectric constant comparable to that of percolative composites are successfully prepared by using core-shell structured hyperbranched aromatic polyamide grafted barium titanate (BT-HBP) hybrid nanofiller. Poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (PVDF-TrFE-CFE) was used as the polymer matrix because of its high intrinsic dielectric constant and easy processability. The BT-HBP hybrid nanofiller were prepared by a solution polymerization of diaminobenzoic acid on the surface of amino-funcationalized BT nanoparticles. Nuclear magnetic resonance ((1)H NMR) and transmission electron microscopy (TEM) were used to verify the chemical structure of the hyperbranched aromatic polyamide and core-shell structure of the hybrid filler, respectively. It was found that the nanocomposite with 40 vol % BaTiO3-HBP had a dielectric constant of 1485.5 at 1000 Hz, whereas the corresponding nanocomposite sample with untreated BaTiO3 only showed a dielectric constant of 206.3. Compared with classic percolative composites, the advantage of the PVDF-TrFE-CFE/BaTiO3-HBP nanocomposites is that the composites show high enough breakdown strength and high dielectric constant simultaneously. An enhanced interfacial polarization mechanism between the BT-HBP and the polymer matrix was suggested for understanding the observed unusually high dielectric constant.