Role, effect, and influences of micro and nano-fillers on various properties of polymer matrix composites for microelectronics: A review

Toward Fully Controllable Monomers Sequence: Binary Organocatalyzed Polymerization from Epoxide/Aziridine/Cyclic Anhydride Monomer Mixture

The sequence of monomers within a polymer chain plays a pivotal role in determining the physicochemical properties of the polymer. In the copolymerization of two or more monomers, the arrangement of monomers within the resulting polymer is primarily dictated by the intrinsic reactivity of the monomers. Precisely controlling the monomer sequence in copolymerization, particularly through the manipulation of catalysts, is a subject of intense interest and poses significant challenges. In this study, we report the catalyst-controlled copolymerization of epoxides, N-tosyl aziridine (TAz), and cyclic anhydrides. To achieve this, a binary catalyst system comprising a Lewis acid, triethylborane, and Brønsted base, t-BuP1, was utilized. This system was utilized to regulate the selectivity between two catalytic reactions: ring-opening alternating copolymerization (ROAC) of epoxides/cyclic anhydrides and ROAC of TAz/cyclic anhydrides. Changing the catalyst ratio made it possible to continuously modulate the resulting poly(ester-amide ester) from ABA-type real block copolymers to gradient, random-like, reversed gradient, and reversed BAB-type block-like copolymers. A range of epoxides and anhydrides was investigated, demonstrating the versatility of this polymerization system. Additionally, density functional theory calculations were conducted to enhance our mechanistic understanding of the process. This synthetic method not only provides a versatile means for producing copolymers with comparable chemical compositions but also facilitates the exploration of the intricate relationship between monomer sequences and the resultant polymer properties, offering valuable insights for advancements in polymer science.

Thermal Conductive Polymer Composites: Recent Progress and Applications

As microelectronics technology advances towards miniaturization and higher integration, the imperative for developing high-performance thermal management materials has escalated. Thermal conductive polymer composites (TCPCs), which leverage the benefits of polymer matrices and the unique effects of nano-enhancers, are gaining focus as solutions to overheating due to their low density, ease of processing, and cost-effectiveness. However, these materials often face challenges such as thermal conductivities that are lower than expected, limiting their application in high-performance electronic devices. Despite these issues, TCPCs continue to demonstrate broad potential across various industrial sectors. This review comprehensively presents the progress in this field, detailing the mechanisms of thermal conductivity (TC) in these composites and discussing factors that influence thermal performance, such as the intrinsic properties of polymers, interfacial thermal resistance, and the thermal properties of fillers. Additionally, it categorizes and summarizes methods to enhance the TC of polymer composites. The review also highlights the applications of these materials in emerging areas such as flexible electronic devices, personal thermal management, and aerospace. Ultimately, by analyzing current challenges and opportunities, this review provides clear directions for future research and development.

Temperature Dependence of the Polar and Lewis Acid-Base Properties of Poly Methyl Methacrylate Adsorbed on Silica via Inverse Gas Chromatography

The adsorption of polymers on solid surfaces is common in many industrial applications, such as coatings, paints, catalysis, colloids, and adhesion processes. The properties of absorbed polymers commonly vary with temperature. In this paper, inverse gas chromatography at infinite dilution was used to determine the physicochemical characterization of PMMA adsorbed on silica. A new method based on the London dispersion equation was applied with a new parameter associating the deformation polarizability with the harmonic mean of the ionization energies of the solvent. More accurate values of the dispersive and polar interaction energies of the various organic solvents adsorbed on PMMA in bulk phase and PMMA/silica at different recovery fractions were obtained, as well as the Lewis acid-base parameters and the transition temperatures of the different composites. It was found that the temperature and the recovery fraction have important effects on the various physicochemical and thermodynamic properties. The variations in all the interaction parameters showed the presence of three transition temperatures for the different PMMA composites adsorbed on silica with various coverage rates, with a shift in these temperatures for a recovery fraction of 31%. An important variation in the polar enthalpy and entropy of adsorption, the Lewis acid-base parameters and the intermolecular separation distance was highlighted as a function of the temperature and the recovery fraction of PMMA on silica.

Development of Polylactic Acid Films with Alkali- and Acetylation-Treated Flax and Hemp Fillers via Solution Casting Technique

This study aims to enhance value addition to agricultural byproducts to produce composites by the solution casting technique. It is well known that PLA is moisture-sensitive and deforms at high temperatures, which limits its use in some applications. When blending with plant-based fibers, the weak point is the poor filler-matrix interface. For this reason, surface modification was carried out on hemp and flax fibers via acetylation and alkaline treatments. The fibers were milled to obtain two particle sizes of <75 μm and 149-210 μm and were blended with poly (lactic) acid at different loadings (0, 2.5%, 5%, 10%, 20%, and 30%) to form a composite film The films were characterized for their spectroscopy, physical, and mechanical properties. All the film specimens showed C-O/O-H groups and the π-π interaction in untreated flax fillers showed lignin phenolic rings in the films. It was noticed that the maximum degradation temperature occurred at 362.5 °C. The highest WVPs for untreated, alkali-treated, and acetylation-treated composites were 20 × 10-7 g·m/m2 Pa·s (PLA/hemp30), 7.0 × 10-7 g·m/m2 Pa·s (PLA/hemp30), and 22 × 10-7 g·m/m2 Pa·s (PLA/hemp30), respectively. Increasing the filler content caused an increase in the color difference of the composite film compared with that of the neat PLA. Alkali-treated PLA/flax composites showed significant improvement in their tensile strength, elongation at break, and Young's modulus at a 2.5 or 5% filler loading. An increase in the filler loadings caused a significant increase in the moisture absorbed, whereas the water contact angle decreased with an increasing filler concentration. Flax- and hemp-induced PLA-based composite films with 5 wt.% loadings showed a more stable compromise in all the examined properties and are expected to provide unique industrial applications with satisfactory performance.

Waste chicken feather biofiller reinforced bioepoxy resin based biocomposites - A waste to wealth experimental approach

Utilizing poultry wastes, particularly chicken feathers, in biopolymer composites is seen as an important aspect in lowering the environmental pollution and paving a new path to sustainability. The main objective of this experimental study is to develop polymer composites reinforced with waste chicken feather fillers and evaluate their physical, mechanical, and thermal characteristics. The composites were fabricated through an open mold casting process using bio epoxy (SR-33 Greenpoxy) as the matrix and chicken feather filler as a reinforcement in three distinct weight fractions (2.5, 5, and 7.5 wt%). To evaluate the effects of filler content on the mechanical properties of the fabricated bio-epoxy composites, they were subjected to tensile, flexural, impact, and hardness tests. The findings from the experimental studies demonstrated that the composites containing 2.5 wt% of chicken feather filler had improved mechanical properties, thermal stability, and crystallization behaviour. The thermal attributes of samples included a greater melting point, lower recrystallization temperature, higher glass transition temperature, and quicker crystallization rates. The Scanning Electron Microscope analysis of the fracture surface morphology of the biocomposites showed a better interfacial adhesion between the filler and matrix. It could be concluded from the results that the waste chicken feather can be used as potential filler reinforcements for begetting natural composites for various low- and medium-density structural and non-structural applications.

Review of sustainable, eco-friendly, and conductive polymer nanocomposites for electronic and thermal applications: current status and future prospects

Biodegradable polymer nanocomposites (BPNCs) are advanced materials that have gained significant attention over the past 20 years due to their advantages over conventional polymers. BPNCs are eco-friendly, cost-effective, contamination-resistant, and tailorable for specific applications. Nevertheless, their usage is limited due to their unsatisfactory physical and mechanical properties. To improve these properties, nanofillers are incorporated into natural polymer matrices, to enhance mechanical durability, biodegradability, electrical conductivity, dielectric, and thermal properties. Despite the significant advances in the development of BPNCs over the last decades, our understanding of their dielectric, thermal, and electrical conductivity is still far from complete. This review paper aims to provide comprehensive insights into the fundamental principles behind these properties, the main synthesis, and characterization methods, and their functionality and performance. Moreover, the role of nanofillers in strength, permeability, thermal stability, biodegradability, heat transport, and electrical conductivity is discussed. Additionally, the paper explores the applications, challenges, and opportunities of BPNCs for electronic devices, thermal management, and food packaging. Finally, this paper highlights the benefits of BPNCs as biodegradable and biodecomposable functional materials to replace traditional plastics. Finally, the contemporary industrial advances based on an overview of the main stakeholders and recently commercialized products are addressed.

The Influence of Titanium Dioxide (TiO2) Particle Size and Crystalline Form on the Microstructure and UV Protection Factor of Polyester Substrates

The inclusion of particles in a polymeric substrate to achieve certain properties is a well-known practice. In the case of textile substrates, this practice may deeply affect the structure of the produced yarns, as even a filament with no textile applications can be obtained. In this manuscript, titanium dioxide (TiO2) particles were incorporated into polyester (PET) chips and the influence of these fillers on the properties of yarn and fabric, and the ultraviolet protection factor (UPF) was assessed. For this purpose, rutile and anatase crystalline forms of TiO2, as well as the size of the particles, were evaluated. Moreover, parameters such as mechanical properties, orientation of the macromolecules and thermal behavior were analyzed to ensure that the textile grade is maintained throughout the production process. The results showed that the inclusion of micro- and nanoparticles of TiO2 decreases the molecular weight and tenacity of PET. Also, although orientation and crystallinity varied during the textile process, the resulting heatset fabrics did not present important differences in those parameters. Finally, the attainment of textile-grade PET-TiO2 fabrics with UPF indexes of 50+ with both rutile and anatase and micro- and nano-sized TiO2 forms was demonstrated.

Biodegradable Fiber-Reinforced Gluten Biocomposites for Replacement of Fossil-Based Plastics

Biocomposites based on wheat gluten and reinforced with carbon fibers were produced in line with the strive to replace fossil-based plastics with microplastic-free alternatives with competing mechanical properties. The materials were first extruded/compounded and then successfully injection molded, making the setup adequate for the current industrial processing of composite plastics. Furthermore, the materials were manufactured at very low extrusion and injection temperatures (70 and 140 °C, respectively), saving energy compared to the compounding of commodity plastics. The sole addition of 10 vol % fibers increased yield strength and stiffness by a factor of 2-4 with good adhesion to the protein. The biocomposites were also shown to be biodegradable, lixiviating into innocuous molecules for nature, which is the next step in the development of sustainable bioplastics. The results show that an industrial protein coproduct reinforced with strong fibers can be processed using common plastic processing techniques. The enhanced mechanical performance of the reinforced protein-based matrix herein also contributes to research addressing the production of safe materials with properties matching those of traditional fossil-based plastics.

Unsaturated Polyester Resin Filled with Cementitious Materials: A Comprehensive Study of Filler Loading Impact on Mechanical Properties, Microstructure, and Water Absorption

In recent years, cheaply available cementitious materials (CMs) are increasingly finding useful applications in construction engineering. This manuscript focused on the development and fabrication of unsaturated polyester resin (UPR)/cementitious material composites to be potentially useful in a variety of construction applications. For this purpose, five types of powders from widely available fillers, i.e., black cement (BC), white cement (WC), plaster of Paris (POP), sand (S), and pit sand (PS), were used. Cement polymer composite (CPC) specimens were prepared by a conventional casting process with various filler contents of 10, 20, 30, and 40 wt %. Neat UPR and CPCs were investigated mechanically by testing their tensile, flexural, compressive, and impact properties. Electron microscopy analysis was used to analyze the relation between the microstructure and mechanical properties of CPCs. The assessment of water absorption was conducted. The highest tensile, flexural, compressive upper yield, and impact strength values were recorded for POP/UPR-10, WC/UPR-10, WC/UPR-40, and POP/UPR-20, respectively. The highest percentages of water absorption were found to be 6.202 and 5.07% for UPR/BC-10 and UPR/BC-20, while the lowest percentages were found to be 1.76 and 1.84% for UPR/S-10 and UPR/S-20, respectively. Based on the finding of this study, the properties of CPCs were found to depend on not only the filler content but also the distribution, particle size, and combination between the filler and the polymer.

Effect of carbons' structure and type on AC electrical properties of polymer composites: predicting the percolation threshold of permittivity through different models

The AC electrical properties of EVA- and NBR-based composites filled with different conductive fillers were investigated. Result shows several magnitudes of increment in AC electrical conductivity and dielectric permittivity after the addition of these conductive fillers, indicating that these materials can be used as supercapacitors. The magnitude of increment was varied according to polymer and filler types. Herein, we also have tested the applicability of different sigmoidal models to find out the percolation threshold value of permittivity for these binary polymer composite systems. It is observed that except sigmoidal-Boltzmann and sigmoidal-dose-response models, other sigmoidal models exhibit different values of percolation threshold when considered for any particular polymer composite system. The paper discusses the variation in results of percolation threshold with an emphasis on the advantages, disadvantages and limitations of these models. We also have applied the classical percolation theory to predict the percolation threshold of permittivity and compared with all the reported sigmoidal models. To judge the unanimous acceptability of these models, they tested vis-à-vis the permittivity results of various polymer composites reported in published literature. To comprehend, all the models except the sigmoidal-logistic-1 model were successfully applicable for predicting the percolation threshold of permittivity for polymer composites.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00396-023-05120-2.

Effect of silane coupling agent and concentration on fracture toughness and water sorption behaviour of fibre-reinforced dental composites

OBJECTIVES

This paper presents the effect of silane treatment of S-2 Glass fibres on the fracture toughness and water sorption/solubility behaviour of fibre-reinforced flowable dental composites. The effect of epoxy- and methacrylate-based silane coupling agents (SCAs) on the mechanical strength and hydrolytic properties were investigated. The concentration of the selected SCAs on the mechanical and physical properties were investigated. The influence of molecular structure and concentration in the interfacial adhesion at the fibre-matrix interfaces was also studied.

METHODS

Short S-2 Glass fibres of 250 µm in length and 5 µm in diameter were etched with acid to remove any impurities and roughen the surface. The acid-etched fibres were silane treated with 3MPS, 3GPS, and 8MOTS at different concentrations by weight (%). The silane-treated fibres were incorporated at 5 % into the dental resin mixture. Untreated fibres were added at 5 % to the dental resin mixture and served as the control group. The physical properties such as water sorption, solubility, and desorption along with mechanical properties such as fracture toughness and total fracture work of the fibre-reinforced dental composites grafted with the above-mentioned SCAs were evaluated. The surface morphology of the fractured surface was studied and analysed.

RESULTS

The fracture toughness tests showed that the dental composites grafted with optimum weight per cent (wt. %) concentration of the SCA had a better stress intensity factor (K_IC) when compared to the 2.0 wt. % and 3.0 wt. % concentration. The K_IC value of dental composites grafted with untreated surface etched glass fibres was less than the K_IC values of dental composites grafted with optimum concentrations of 3MPS, 3GPS, and 8MOTS by 81.6 %, 38.6 %, and 110.5 %, respectively. A similar trend was found while investigating the total work of fracture of the dental composites, between optimum concentration, 2.0 wt. % and 3.0 wt. % concentration of respective SCA. The increase in silane concentration also led to an increase in the water sorption/solubility characteristics. The absorption of water was most severe in the fibre-reinforced dental composites without silane treatment (32.9 µg/mm³). The ANOVA results showed that the fibre-reinforced dental composites grafted with 8MOTS at optimum concentration showed an increase in fracture toughness when compared to optimum concentrations of 3GPS and 3MPS by 51.9 % and 15.9 %, respectively. The enhanced mechanical and physical characteristics are due to the increased adhesion between the fibre and silane achieved from the optimum wt. % concentration of 8MOTS. Similarly, dental composites grafted with 8MOTS at optimum concentration showed a decrease in water sorption characteristics when compared to optimum concentrations of 3GPS and 3MPS by 18.2 % and 0.6 %, respectively. The decreased water sorption characteristics at the optimum concentration of 8MOTS could be due to the reduced availability of reactive hydroxyl groups and the hydrophobic characteristics of 8MOTS.

SIGNIFICANCE

Silane coupling agents (SCAs) are important components of dental composites. The type and concentration of SCA have a significant effect on material properties. The current study focuses on understanding the effects of different SCAs and wt. % concentrations on the interfacial fracture behaviour and the influence of different SCAs on the water sorption and solubility behaviour of S-2 Glass fibre-reinforced flowable dental composites.

Interface damage and fracture mechanisms of a ceramic/polymer interface based on atomic-scale simulations

The performance of ceramic/polymer composite materials is significantly affected by their internal interfaces. To reveal the intrinsic interface fracturing mechanism of ceramic/polymer interfaces, an interfacial model composed of SiO₂ and polypropylene (PP) is investigated using the molecular dynamics method. The interface damage is quantified by the increase in the interface free volume and deformation of a single PP chain. As stretching speeds increase, the free volume and outflowing atoms of PP chains decrease with the same interfacial displacement, which results in the increase of the interface strength and fracture energy. At low stretching speeds, the interface damage mechanism is determined by a competition between attractions of the PP single chains from SiO₂ and PP. In contrast, at higher stretching speeds, the interface fracture is more brittle and the interface strength and fracture energy are both higher owing to the smaller cavity ratio. The results of this study contribute to an in depth understanding of the fracture mechanism of ceramic/polymer interfaces in many systems.

Challenges and issues with the performance of boron nitride rooted membrane for gas separation

Various fillers such as zeolites, metal-organic framework, carbon, metal framework, graphene, and covalent organic framework have been incorporated into the polymers. However, these materials are facing issues such as incompatibility with the polymer matrix, which leads to the formation of non-selective voids and thus, reduces the gas separation properties. Recent studies show that hexagonal boron nitride (h-BN) possesses attractive characteristics such as high aspect ratio, good compatibility with polymer materials, enhanced gas barrier performance, and improved mechanical properties, which could make h-BN the potential candidate to replace conventional fillers. The synthesis of materials and membranes is the subject of this review, which focuses on recent developments and ongoing problems. Additionally, a summary of the mathematical models that were utilised to forecast how well polymer composites would perform in gas separation is provided. It was found in the previous studies that tortuosity is the governing factor for the determination of the effectiveness of a nanofiller as a gas barrier enhancer in polymer matrices. The shape of the nanofiller particles and sheets, disorientation and distribution of the nanofillers within the polymer matrix, state of aggregation and rate of reaggregation of the nanofiller particles, as well as the compatibility of the nanofiller with the polymer matrix all played a significant role in determining how well a particular nanofiller will perform in enhancing the gas barrier properties of the nanocomposites. For this purpose, this review has been focused not only on the experimentation work but also on the effect of tortuosity, exfoliation quality, compatibility, disorientation, and reaggregation of nanofillers.

Molecularly Engineered Unparalleled Strength and Supertoughness of Poly(urea-urethane) with Shape Memory and Clusterization-Triggered Emission

To address the challenge of realizing multifunctional polymers simultaneously exhibiting high strength and high toughness through molecular engineering, ultrastrong and supertough shape-memory poly(urea-urethane) (PUU) is fabricated by regulating: i) the reversible cross-links composed of rigid units and multiple hydrogen bonds, and ii) the molecular weight of soft segments. The optimal material exhibits an unparalleled strength of 84.2 MPa at a large elongation at a break of 925.6%, a superior toughness of 322.8 MJ m^-3 , and remarkable fatigue resistance without fracture. The repeated stretching of this material induces an irreversible deformation, which, however, can be rapidly recovered by heating. Moreover, all samples are capable of temporary shape fixation at -40 °C (recovering the original shape at 30 °C) and exhibit blue fluorescence when excited at the optimum wavelength, which is ascribed to clusterization-triggered emission (CTE) due to the formation of microphase-separation structures. Thus, the adopted approach provides a solution to a long-standing problem and paves the way to the realization of intrinsically luminescent shape-memory materials exhibiting both ultrahigh strength and ultrahigh toughness.

Synthesis and Characterization of Polymeric Blends Containing Polysulfone Based on Cyclic Bisphenol

The elaboration of the composition and methods of preparation of new types of materials is an important issue from the plastics industry’s point of view. The paper presents the polysulfone synthesis based on 4,4′-cyclohexylidenebisphenol (bisphenol Z). This compound was used (in an amount of 5 or 10 wt.% sample) for the synthesis and characterization of new polymeric blends based on the two different acrylic resins (EB-150 and EB-600) and the active solvent N-vinyl-2-pyrrolidone (NVP). The weight ratio of the used resin to solvent was 1:2; 1:1 or 2:1. These new materials were obtained applying the photoinitiated free radical polymerization with 2,2-dimethoxy-2-phenyloacetophenone as a photoinitiator used in an amount of 1 wt.%. Six polymeric blends and six copolymers without polysulfone were cured by this method. By means of ATR/FT-IR (Attenuated Total Reflection–Fourier Transform Infrared) spectroscopy the chemical structure of the synthesized polysulfone was proved. The effect of the presence of the polysulfone presence on the thermal properties of the obtained blends was analyzed by means of thermogravimetry and differential thermogravimetry (TG/DTG), as well as differential scanning calorimetry (DSC). Moreover, the dynamic mechanical studies (DMA) of these materials were also carried out, demonstrating which of the materials showed the influence of the percentage of polysulfone on the selected properties in the blended- and parent-copolymers samples.

Anti-Wear and Anti-Erosive Properties of Polymers and Their Hybrid Composites: A Critical Review of Findings and Needs

Erosion caused by the repeated impact of particles on the surface of a substance is a common wear method resulting in the gradual and continual loss of affected objects. It is a crucial problem in several modern industries because the surfaces of various products and materials are frequently subjected to destructively erosive situations. Polymers and their hybrid materials are suitable, in powdered form, for use as coatings in several different applications. This review paper aims to provide extensive information on the erosion behaviors of thermoset and thermoplastic neat resin and their hybrid material composites. Specific attention is paid to the influence of the properties of selected materials and to impingement parameters such as the incident angle of the erodent, the impact velocity of the erodent, the nature of the erodent, and the erosion mechanism. The review further extends the information available about the erosion techniques and numerical simulation methods used for wear studies of surfaces. An investigation was carried out to allow researchers to explore the available selection of materials and methods in terms of the conditions and parameters necessary to meet current and future needs and challenges, in technologically advanced industries, relating to the protection of surfaces. During the review, which was conducted on the findings in the literature of the past fifty years, it was noted that the thermoplastic nature of composites is a key component in determining their anti-wear properties; moreover, composites with lower glass transition, higher ductility, and greater crystallinity provide better protection against erosion in advanced surface applications.

Obtaining Greatly Improved Dielectric Constant in BaTiO3-Epoxy Composites with Low Ceramic Volume Fraction by Enhancing the Connectivity of Ceramic Phase

Ceramic-polymer dielectric composites show promising potential as embedded capacitors, whereas it is a great challenge to obtain a high dielectric constant (ε_r) at a low ceramic volume fraction (V_c). This work demonstrates a strategy for overcoming this challange. By employing a high sintering temperature (T_s) and introducing porogen, BaTiO₃ ceramics with both great connectivity and high porosity are obtained, and the composites with improved ε_r at a low V_c are prepared after curing the epoxy monomer, which is infiltrated into the porous ceramic bodies. For the composite with a T_s of 1300 °C and a V_c of 38.1%, the ε_r is as high as 466.8 at 1 kHz, which is improved by about nine times compared to the 0-3 counterpart with a higher V_c of 60.8%. Furthermore, the composite exhibits low dielectric loss and good frequency and temperature stability of ε_r, indicating the great potential for practical applications. Finite element simulation shows that the enhanced connectivity of BaTiO₃ increases the electric field intensity in high-ε_r BaTiO₃ dramatically and therefore plays a key role in the dielectric response of the composite. This work not only sheds light on the high-ε_r ceramic-polymer composites but also deepens the understanding on the relationship between their properties and microstructures.

ABS/Silicon Dioxide Micro Particulate Composite from 3D Printing Polymeric Waste

In this paper, Acrylonitrile-Butadiene-Styrene matrix composites reinforced with Nano-silica dioxide particles were examined and prepared to study their mechanical properties. The composite sheets were pre-prepared using the hot extrusion process. Due to its wide characteristics, silica dioxide additions can strengthen the usability and mechanical features of composite thermoplastics and polymers. Furthermore, introducing silica dioxide as a filler in various attributes can help to maintain the smooth flow of sufficient powders, reduce caking, and manage viscoelasticity. Despite its advantages, 3D printing generates a significant amount of waste due to limited prints or destroyed support structures. ABS is an ideal material to use because it is a thermoplastic and amorphous polymer with outstanding thermal properties that is also applicable with the FFF (Fused Filament Fabrication) technique. The findings showed that increasing the silica dioxide content reduces the tensile strength to 22.4 MPa at 10 wt%. Toughness, ductility, and yield stress values of ABS/silica dioxide composites at 15 wt% increased, indicating that the composite material reinforced by the silica dioxide particles improved material characteristics. It is essential to consider the impact of recycling in polymer reinforcement with fillers. Furthermore, the improved mechanical qualities of the composite material encourages successful ABS recycling from 3D printing, as well as the possibility of reusing it in a similar application.

Influence of Carbon Nanotubes Concentration on Mechanical and Electrical Properties of Poly(styrene-co-acrylonitrile) Composite Yarns Electrospun

In this work, the influence of carbon nanotubes (CNTs) content on the mechanical and electrical properties of four series of polymeric matrix were made and their cytotoxicity on cells was evaluated to consider their use as a possible artificial muscle. For that, polymer composite yarns were electrospun using polymeric solutions at 10 wt.%. of poly(styrene-co-acrylonitrile) P(S:AN) and P(S:AN-acrylic acid) P(S:AN-AA) at several monomeric concentrations, namely 0:100, 20:80, 40:60, 50:50 (wt.%:wt.%), and 1 wt.% of AA. Carbon nanotubes (CNTs) were added to the polymeric solutions at two concentrations, 0.5 and 1.0 wt.%. PMCs yarns were collected using a blade collector. Mechanical and electrical properties of polymeric yarns indicated a dependence of CNTs content into yarns. Three areas could be found in fibers: CNTs bundles zones, distributed and aligned CNTs zones, and polymer-only zones. PMCs yarns with 0.5 wt.% CNTs concentration were found with a homogenous nanotube dispersion and axial alignment in polymeric yarn, ensuring load transfer on the polymeric matrix to CNTs, increasing the elastic modulus up to 27 MPa, and a maximum electrical current of 1.8 mA due to a good polymer–nanotube interaction.

Silver-doped bioglass modified scaffolds: A sustained antibacterial efficacy

Implant-related bacterial infection is a serious complication, which even causes implant failure. Silver (Ag) nanoparticles are broadly used antibacterial agents due to their excellent antibacterial ability and broad-spectrum bactericidal property. However, the significance of burst release cannot be entirely ignored. In this study, Ag doped mesoporous bioactive glasses (Ag-MBG) nanospheres were synthesized using modified Stöber method, then incorporated into poly L-lactic acid (PLLA) matrix to prepare the composite scaffolds via selective laser sintering (SLS) technology. Herein, Mesoporous bioactive glasses (MBG) sol had many negatively-charged silicon hydroxyl groups, which could adsorb positively-charged Ag ions by electrostatic interaction and eventually form Si-O-Ag bonds into MBG. Moreover, MBG promoted osteoblast colonization due to its continuous release of Si ions. The results showed the Ag-MBG/PLLA scaffold could sustainedly release Ag ions for 28 days, and exhibited significantly antibacterial ability against Escherichia coli, its bacterial inhibition rate was over 80%. In addition, the composite scaffold also showed good cytocompatibility. It may be concluded that the prepared Ag-MBG/PLLA scaffold has great potential to repair implant-associated bone infection.

Voltage-Stabilizer-Grafted SiO2 Increases the Breakdown Voltage of the Cycloaliphatic Epoxy Resin

Cycloaliphatic epoxy (CE) resin plays a vital role in insulation equipment due to its excellent insulation and processability. However, the insufficient ability of CE to confine electrons under high voltage often leads to an electric breakdown, which limits its wide applications in high-voltage insulation equipment. In this work, the interface effect of inorganic nano-SiO2 introduces deep traps to capture electrons, which is synergistic with the inherent ability of the voltage stabilizer m-aminobenzoic acid (m-ABA) to capture high-energy electrons through collision. Therefore, the insulation failure rate is reduced owing to doping of the functionalized nanoparticles of the m-ABA-grafted nano-SiO2 (m-ABA-SiO2) into the CE. It is worth noting that the breakdown field strength of this m-ABA-SiO2/CE reaches 53 kV/mm, which is 40.8% higher than that of pure CE. In addition, the tensile strength and volume resistivity of m-ABA-SiO2/CE are increased by 29.1 and 140%, respectively. Meanwhile, the glass transition temperature was increased by about 25 °C and reached 213 °C. This work proves that the comprehensive performance of CE-based nanocomposites is effectively improved by m-ABA-SiO2 nanoparticles, showing great application potential in high-voltage insulated power equipment.

The Influence of Nano CaCO3 on Nucleation and Interface of PP Nano Composite: Matrix Processability and Impact Resistance

Polypropylene (PP) is a commodity material that has been increasingly used in different industries in the past two decades due to its versatile properties when enhanced with additives. Homo polypropylene, in general, has weak mechanical properties and limited chemical resistance; thus, using a different type of fillers to adjust such properties to fit the required applications opened a large market for this commodity. Understanding the interface constituent between the polymer matrix and the added filler and the nucleation behavior is a key to fine control of the enhancement of PP properties. In this study, PP was incorporated with nano calcium carbonate (CaCO₃) at 2 and 5 wt% in the presence of maleic anhydride (MAH) to overcome the weak interface due to low polymer polarity. The mix was compounded in a twin screws extruder at a temperature range of 180–200 °C ; then, the prepared samples were left to dry for 24 h at 25 °C. Nuclear Magnetic Resonance (NMR) was used to study the interface adhesion of the nanofiller and the curved revealed that at 2% of nano CaCO₃ PP structure remained the same and the nano experienced good adhesion to the polymer matrix. The mechanical impact resistance results showed a real enhancement to the polymer matrix of the nanocomposite by 37%. Moreover, DSC results showed a faster crystallinity rate due to the nanofiller acting as a nucleating agent and rheology tests indicated that low content of nano additive (2%) has better processability behavior, with suitable viscosity complex values at high frequencies.

Polyethersulfone membrane embedded with amine functionalized microcrystalline cellulose

In this investigation, microcrystalline cellulose (MCC) was functionalized with metformin HCl using (3-chloropropyl)triethixysilane (CPTES) as a coupling agent. Polyethersulfone (PES) membranes were incorporated with different concentrations of modified MCC (MMCC) to enhance its affinity for heavy metals during filtration of aqueous solutions. The composite membranes were characterized via fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), atomic force microscopy (AFM), Brunauer-Emmett-Teller (BET) method, porosity and contact angle measurements and mechanical analysis. The presence of MMCC in the host matrix was confirmed by FTIR. Although composites decomposed at lower temperatures, their thermal stability was sufficient to meet their performance requirements. DSC showed enhanced glass transition temperature (T_g) due to the interfacial interactions between membrane constituents which restrict the mobility of polymer chains. Microscopic imaging revealed higher surface roughness of composites compared to neat PES. Inclusion of MMCC increased the porosity and hydrophilicity of the membrane which consequently, higher permeability can be achieved.

Suppressed polarization by epitaxial growth of SrTiO3 on BaTiO3 nanoparticles for high discharged energy density and efficiency nanocomposites

In order to meet the increasing demand of integration and miniaturization of electronic components, capacitors with high energy density are urgently needed. In this work, a strategy of suppressing interfacial polarization for obtaining enhanced energy density and efficiency polymer based nanocomposites is proposed. This strategy is conducted by epitaxial growth of a SrTiO₃ layer with a moderate dielectric constant on the surface of a BaTiO₃ core to form a kind of novel filler and compositing with the P(VDF-HFP) matrix to prepare dielectric nanocomposites. The SrTiO₃ shell could effectively confine the mobility of charge carriers to enhance the dielectric strength of the composites and improve the energy efficiency by reducing the Maxwell-Wagner-Sillars (MWS) interfacial polarization and space charge polarization between the BaTiO₃@SrTiO₃ fillers and the P(VDF-HFP) matrix due to their similar crystal structure and lattice parameter. The nanocomposite containing 1 vol% BaTiO₃@SrTiO₃ nanoparticles achieved a discharged energy density of 13.89 J cm^-3 and an energy efficiency of 63% at 494.7 kV mm^-1, which are superior to 9.96 J cm^-3 and 50% of BaTiO₃/P(VDF-HFP) nanocomposites with the same loading, respectively, and its discharged energy density is 69% higher than 8.2 J cm^-3 of the neat P(VDF-HFP) at 401.5 kV mm^-1. This work provides an effective way for nanocomposite capacitors with high energy density and efficiency.

Interface design for high energy density polymer nanocomposites

This review provides a detailed overview on the latest developments in the design and control of the interface in polymer based composite dielectrics for energy storage applications. The methods employed for interface design in composite systems are described for a variety of filler types and morphologies, along with novel approaches employed to build hierarchical interfaces for multi-scale control of properties. Efforts to achieve a close control of interfacial properties and geometry are then described, which includes the creation of either flexible or rigid polymer interfaces, the use of liquid crystals and developing ceramic and carbon-based interfaces with tailored electrical properties. The impact of the variety of interface structures on composite polarization and energy storage capability are described, along with an overview of existing models to understand the polarization mechanisms and quantitatively assess the potential benefits of different structures for energy storage. The applications and properties of such interface-controlled materials are then explored, along with an overview of existing challenges and practical limitations. Finally, a summary and future perspectives are provided to highlight future directions of research in this growing and important area.