Filler Matrix Research Articles

Flexible and lead-free polymer composites for X-ray shielding: comparison of polyvinyl chloride matrix filled with nanoparticles of tungsten oxides.

Polymer nanocomposites have been investigated as lightweight and suitable alternatives to lead-based clothing. The present study aims to fabricate flexible, lead-free, X-ray-shielding composites using a polyvinyl chloride (PVC) matrix and different nanostructures. Four different nanostructures containing impure tungsten oxide, tungsten oxide (WO3), barium tungstate (BaWO4), and bismuth tungstate (Bi2WO6) were synthesized through various methods. Subsequently, their morphological characteristics were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Also, energy-dispersive X-ray spectroscopy (EDS) analysis was performed to establish the presence of the filler in the PVC matrix. Two different weight ratios of these nanostructures (20% wt and 50% wt) were used to produce the PVC composites. To investigate attenuation parameters, the prepared composites were irradiated with X-rays at tube voltages of 40, 80, and 120kV. The results showed that the PVC composites containing 20% wt Bi2WO6 had the highest linear attenuation coefficient (µ) at all three voltages. Furthermore, they had the lowest half-value layer (HVL), tenth-value layer (TVL), and 0.5mm equivalent lead thickness values at each of the three voltages. The PVC composites containing 50% wt Bi2WO6 had attenuation coefficients greater than those reported for PbO at all three X-ray voltages. Among the studied tungsten nanostructures, bismuth tungstate had the best attenuation performance for X-ray protection. Additionally, this composite is light, flexible, and non-toxic, making it a promising alternative to lead aprons.

Boron nitride–Ag NWs/polyvinyl alcohol films with high thermal conductivity and excellent mechanical properties prepared via air/water interfacial assembly

Boron nitride–Ag NWs/polyvinyl alcohol films with high thermal conductivity and excellent mechanical properties as thermal management materials were prepared via air/water interfacial assembly.

Recent Advances in Creating 3D-interconnected Networks within Thermally Conductive Aluminum Nitride Polymer Composites: A Review

Abstract: The demand for efficient heat dissipation in advanced electronic devices necessitates the development of polymer composites with exceptional thermal conductivity. Over the course of the last few years, a great deal of research has been conducted to augment the thermal management of polymer composites through the incorporation of fillers possessing exceptionally high thermal conductivity. Among these fillers, aluminum nitride (AlN) has emerged as an exemplary choice for enhancing the thermal conductivity properties of polymer composites. Nevertheless, the substantial thermal resistance that exists at the interface of the filler and polymer matrix, as well as between fillers themselves, significantly impedes heat conduction, thereby limiting the improvement in thermal conductivity. The concise review endeavors to illustrate the recent advancements in the production techniques of polymer/AlN composites that exhibit high thermal conductivity by creating a three-dimensional interconnected filler network. The review begins with an introduction to the proposed mechanisms of heat conductivity in polymer composites, followed by a brief discussion of the various factors influencing the thermal conductivity of these composites. Subsequently, the different methods for fabricating three-dimensional interconnected AlN networks in polymer/AlN composites, all aimed at enhancing thermal conductivity, are presented. The review aims to present novel methods for improving the thermal conductivity of polymer composites by building complex three-dimensional filler networks.

Analysis of Interfacial Adhesion Properties Between PBT Azide Propellant Matrix and Defective AP Fillers Using Molecular Dynamics Simulations.

Filler defects and matrix crosslinking degree are the main factors affecting the interfacial adhesion properties of propellants. Improving adhesion can significantly enhance debonding resistance. In this study, all-atom molecular dynamics (MD) simulations are employed to investigate the interfacial adsorption behavior and mechanisms between ammonium perchlorate (AP) fillers and a poly(3,3-bis-azidomethyl oxetane)-tetrahydrofuran (PBT) matrix. This study focuses on matrix crosslinking degree (70-90%), AP defects (width 20-40 Å), and temperature effects (200-1000 K) to analyze microscopic interfacial adsorption behavior, binding energy, and radial distribution function (RDF). The simulation results indicate that higher crosslinking of the PBT matrix enhances interfacial adsorption strength, but incomplete crosslinking reduces this strength. Defects on the AP surface affect interfacial adsorption by altering the contact area, and defects of 30 Å width can enhance adsorption. The analysis of temperature effects on binding energy and interface RDF reveals that binding energy and interface RDF fluctuate as the temperature increases. This study provides a microscopic perspective on the PBT matrix-AP interfacial adsorption mechanism and provides insights into the design of PBT azide propellant fuels.

Dielectric properties of polymer mixtures with CaTiO3 perovskite: conventional and plasma-treated ceramic powders

ABSTRACT We studied dielectric properties of a composite consisting of organic matrix and ceramic filler based on a high-permittivity CaTiO3. This very stable ceramic dielectric material was added into Dentacryl polymer in various proportions up to 32 vol.%. Besides crushed powder, a plasma-treated powder of a hollow character was applied. The ceramics contributed to a markedly enhanced permittivity of the composite, whereas the losses remained rather low and the DC resistivity high (εr = 30, tan δ = 0.05, ρv = 1013 Ωm). The system followed the mathematical model – the mixing rules concerning the frequency-dependent response to the electric field, whereas rather low concentrations of the CaTiO3 admixture were high enough to increase the dielectric characteristics over the mean values predicted by the mixing rules. This behaviour was typical mainly for the hollow powder, which enhanced the dielectric performance stronger than the ordinary form of CaTiO3 powder. However, because of less lossy character, the crushed powder of a traditional technology origin is more universal for making dielectric composites.

Effect of chairside polishing systems on the surface roughness of different CAD-CAM denture base materials

Adjusting and polishing a denture base affects surface roughness and, consequently, microbial adhesion. Since various computer-aided design and computer-aided manufacturing (CAD-CAM) denture base materials are available, the efficiency of chairside polishing systems to achieve a proper surface roughness should be investigated. The purpose of this in vitro study was to compare the surface roughness of milled and 3-dimensional (3D) printed denture base materials with that of heat-polymerized acrylic resin after the use of 2 different chairside polishing systems. Heat-polymerized (control), milled, and 3D printed denture base materials were tested. Laboratory polished and unpolished denture bases served as positive and negative controls. Specimens were divided into 2 chairside silicone polishing systems (AcryPoint system and Exa technique). Surface roughness was measured before and after polishing. Surface morphology of the unpolished and polished specimens was observed via scanning electron microscopy. The surface hardness of unpolished specimens was measured using a Vickers hardness tester. Stress-strain behavior of the silicone matrix and abrasive filler size of each polisher was assessed. The effects of denture base materials and polishing systems on surface roughness and hardness were evaluated using 1-way, 2-way, and repeated measures analyses of variance (ANOVA) (α=.05), along with Weibull proportional hazards regression to assess the likelihood of achieving clinically acceptable surface roughness. The Spearman correlation assessed the relationship between the hardness of unpolished denture bases and final surface roughness. The surface roughness of all denture bases decreased with increased polishing duration, reaching a plateau after 60 seconds. For the heat-polymerized and milled dentures, the Exa technique consistently yielded lower roughness than the AcryPoint system (P<.001). Conversely, both polishing systems produced comparable surface roughness on the 3D printed denture base. The Vickers hardness of the unpolished milled denture was significantly higher than of the others (P=.010). The stress-strain behavior of the polisher matrix revealed distinct characteristics between coarse or medium and fine polishers within each polishing system. The abrasive filler size of the AcryPoint coarse polisher was relatively larger than that of the Exa technique. Regardless of polishing protocols, the 3D printed denture base exhibited the highest surface roughness, followed by heat-polymerized and milled denture bases. The surface roughness of the polished denture was not related with the material hardness. For heat-polymerized and milled dentures, a chairside silicone polishing system can be used to attain a level of surface roughness similar to that of laboratory polishing, depending on the properties of the chairside silicone polishing system. The data that support the findings of this study are available upon request from the corresponding author.

Hybrid Alumina-Silica Filler for Thermally Conductive Epoxidized Natural Rubber.

Thermally conductive composites were prepared based on epoxidized natural rubber (ENR) filled with alumina, silica, and hybrid alumina and silica. The thermal conductivity and mechanical properties were assessed. It was observed that the interactions of polar functional groups in the fillers and epoxy group in ENR supported a fine dispersion of filler in the ENR matrix. The mechanical properties were improved with alumina, silica, and hybrid alumina/silica loadings. The ENR/Silica composite at 50 phr of silica provided the highest 60 shore A hardness, a maximum 100% modulus up to 0.37 MPa, and the highest tensile strength of 27.3 MPa, while ENR/Alumina with 50 phr alumina gave the best thermal conductivity. The hybrid alumina/silica filler at 25/25 phr significantly improved the mechanical properties and thermal conductivity in an ENR composite. That is, the thermal conductivity of the ENR/Hybrid filler was 2.23 W/mK, much higher than that of gum ENR (1.16 W/mK). The experimental results were further analyzed using ANOVA and it was found that the ENR/Hybrid filler showed significant increases in mechanical and thermal properties compared to gum ENR. Moreover, silica in the hybrid composites contributed to higher strength when compared to both gum ENR and ENR/Alumina composites. The hybrid filler system also favors process ability with energy savings. As a result, ENR filled with hybrid alumina/silica is an alternative thermally conductive elastomeric material to expensive silicone rubber, and it could have commercial applications in the fabrication of electronic devices, solar energy conversion, rechargeable batteries, and sensors.

Tensile, Flexural, and Fatigue Responses of Lightweight Pumice-Reinforced Magnesium Composite: Experimentation Followed by an Analytical Modeling

Abstract Featherweight material to sustain mountainous loads is an extreme contrast. Still, in reality, the automobile and aerospace industries seek very light materials with high specific strength to survive in global competition. This study offers a timely answer to the problems faced by those sectors. Through the use of a stir-assisted squeeze casting method, the current investigation aims to generate a lightweight magnesium composite that is reinforced with porous low-density pumice particles at weight percentages of 5%, 10%, and 15%. An examination of the density indicates that there is a downward tendency in conjunction with the growing reinforcement. In comparison to the magnesium alloy in its natural state, the Pumice 15 coupon achieves a tensile strength increment of 47%, flexural strength increment of 35%, and a 10-time increment in service cycle at fatigue increase. The micromechanics model is implemented to justify the strengthening process in terms of the adhesion between the filler matrix and the interface shear strength. The property plots that were drafted provide evidence that the suggested material is lightweight while exhibiting a significant amount of strength in tensile, flexural, and fatigue. Post-fracture surface morphology analysis exhibits distinct tensile, flexural, and fatigue patterns.

Cellulose-Based Crosslinked and Reinforced Sulfonated Poly(ether ether ketone) Membranes for Robust Proton Exchange Membranes in Fuel Cells

Proton exchange membrane fuel cells (PEMFCs) are a promising clean energy solution due to their high efficiency and eco-friendly operation. Central to their function is the proton exchange membrane (PEM), typically composed of perfluorosulfonic acid (PFSA) ionomers like Nafion and Aquivion. However, challenges such as cost, gas crossover, and limited temperature range persist. To address these, researchers explore hydrocarbon (HC)-based polymers like sulfonated poly(ether ether ketone) (SPEEK), prized for cost-effectiveness and stability. However, HC-based polymers suffer from issues like unstable mechanical behavior and reduced proton conductivity under low humidity, necessitating further development for practical application.In this study, we propose two approaches to overcome these drawbacks of HC-based PEMs. Firstly, we prepare crosslinked SPEEK membranes with cellulose acetate to enhance proton conduction under low RH conditions and stabilize membrane properties. The crosslinked structure of SPEEK/cellulose membranes is investigated using small-angle X-ray scattering, atomic force microscopy, and transmission electron microscopy. Additionally, we incorporate cellulose-based nanofibers obtained by electrospinning as a reinforcing substrate, enhancing the interaction between the SPEEK matrix and cellulose nanofiber filler. This results in a dense membrane without voids, effectively preventing gas crossover and improving membrane robustness. These investigations using cellulose-containing SPEEK membranes lead to enhanced power density and durable operation of fuel cells, particularly at low RH conditions.

Composite Solid-State Electrolyte with Vertical Ion Transport Channels for All-Solid-State Lithium Metal Batteries.

Composite solid electrolytes (CSEs) consisting of polymers and fast ionic conductors are considered a promising strategy for realizing safe rechargeable batteries with high energy density. However, randomly distributed fast ionic conductor fillers in the polymer matrix result in tortuous and discontinuous ion channels, which severely constrains the ion transport capacity and restricts its practical application. Here, CSEs with highly loaded vertical ion transport channels are fabricated by magnetically manipulating the alignment of Li0.35La0.55TiO3 nanowires. The construction of densely packed, vertically aligned ion transport channels can effectively enhance the ion transport capacity of the electrolyte, thereby significantly increasing ionic conductivity. At room temperature (RT), the presented CSE exhibits a remarkable ionic conductivity of up to 2.5 × 10-4 S cm-1. The assembled LiFePO4/Li cell delivers high capacities of 118 mAh g-1 at 5 C at 60°C and a RT capacity of 115 mAh g-1 can be achieved at a charging rate of 0.5 C. This work paves an encouraging avenue for further development of advanced CSEs that favor lithium metal batteries with high energy density and electrochemical performance.

Remarkable improvement in radiation shielding efficiency, thermal insulation performance and compressive strength of rigid polyurethane foam composites by synergetic effect of PbO and colemanite fillers

Developing radiation shielding materials is a critical phenomenon for protecting people and the environment with the increment in usage of nuclear technology in today's world. With this sense, PbO/colemanite-filled rigid polyurethane foams were fabricated by one-shut free rise method, and their performances were investigated via the advanced characterization techniques such as ATR-FTIR, SEM-EDS, TGA as well as thermal conductivity, universal mechanical and radiation shielding tests. The characteristic properties of the samples were evaluated in detail depending on the variation in the filler contents. The ATR-FTIR analysis illustrated that RPUF matrices exhibited good compatibility with the fillers by forming the secondary chemical bonds. Furthermore, SEM analysis revealed that the samples with low PbO/colemanite fillers exhibited fairly uniform and regular cellular morphology with anisotropic elliptical apparition thanks to synergetic catalytic effect of the filler particles, whereas, at high content, some local distortions with slightly chaotic appearance were observed accompanied by viewing the little ruptures and bursts in cell face and collapsed in cell plateau borders. TGA measurement indicated that the inclusion of the fillers into RPUF got worse the samples with comparison of neat RPUF due to the reduction in crosslinking density of the foam. Remarkable improvement (about 25 %) was also obtained in thermal insulation performance at the foam composites containing the fillers due to highly augmentation in number of closed cells and presence of more immobile CO2 gas inside the cells. Furthermore, high inclusion of the fillers in RPUF matrix improved compressive strength of the foams by nearly 15 % by enhancing the bending moment and rigidity of RPUF matrices via contributing to the overall stress dispersion. According to linear and mass attenuation coefficients results, the foam composites displayed excellent X-ray radiation shielding performance with increasing of PbO/colemanite content thanks to the density increment and presence of the atoms with high atomic number. Furthermore, at low photon energy levels, better shielding against X-ray radiation was obtained, while vice versa at high energy levels.

Production of a Wood–Plastic Composite with Wastes from Disposable Masks and Corrugated Cardboard: A Sustainable Post-Pandemic Approach

The increasing demand for disposable textile products, personal care items, and electronic commerce has led to a substantial rise in waste generation, particularly from nonwoven fabric masks (wNWFs) and corrugated cardboard (wCC). This study assessed the feasibility of utilizing these waste materials, which were produced in significant amounts during the COVID-19 pandemic, as both a matrix and reinforcement filler in wood–plastic composites (WPCs). The WPC was fabricated using either two extrusion cycles or thermokinetic homogenization, with both processes being followed by hot pressing. The formulations consisted of virgin polypropylene (vPP), wNWF, and wCC in proportions of 45, 45, and 10 wt %, respectively. The results demonstrated that the composites produced via two extrusion cycles exhibited a tensile strength that was 85% higher and three-point flexural strength three times greater than those produced through thermokinetic homogenization. These findings contribute to advancements in scientific and technological knowledge and offer an efficient solution for managing these types of waste, which continue to be generated post-pandemic.

Molecular Mechanism of Physical and Mechanical Improvement in Graphene/Graphene Oxide-Epoxy Composite Materials.

The performance provided by graphene (Gr) and graphene oxide (GO) additives can be improved by achieving strong adhesion and uniform dispersion in the epoxy resin matrix. In this study, molecular modeling and simulation of DGEBA/DETA based epoxy nanocomposites containing Gr and GO additives were performed. Density functional theory and molecular dynamics simulations were used to investigate interfacial interaction energies and Young's Modulus. Improvement in the interaction energies was studied by controlling the epoxy:hardener ratio, type and the number of oxygen-containing functional groups on the GO, the mass percentage of Gr/GO filler in the epoxy matrix, size and dispersion of GO in the cell. It was demonstrated that functional groups with up to 10 % oxygen content in GO significantly increase interfacial interaction energy for large size Gr/GO. Increasing DETA type amine ratio in the preparation of epoxy polymers increases the interaction energy for high oxygen content while decreasing the interaction energy for low oxygen content in GO for small size GO with edge functional groups. The performance of material dramatically decreased even at high DETA hardener and high GO mass percentages when the aggregation factor of Gr/GO was included in simulations that explain lower Gr/GO percentages in the experimental studies.

Enhancing CO2/N2 and CO2/CH4 Separation Properties of PES/SAPO-34 Membranes Using Choline Chloride-Based Deep Eutectic Solvents as Additives.

CO2 separation is an important environmental method mainly used in reducing CO2 emissions to mitigate anthropogenic climate change. The use of mixed-matrix membranes (MMMs) arrives as a possible answer, combining the high selectivity of inorganic membranes with high permeability of organic membranes. However, the combination of these materials is challenging due to their opposing nature, leading to poor interactions between polymeric matrix and inorganic fillers. Many additives have been tested to reduce interfacial voids, some of which showed potential in dealing with compatibility problems, but most of them lack further studies and optimization. Deep eutectic solvents (DESs) have emerged as IL substitutes since they are cheaper and environmentally friendly. Choline chloride-based deep eutectic solvents were studied as additives in polyethersulfone (PES)/SAPO-34 membranes to improve CO2 permeability and CO2/N2 and CO2/CH4 selectivity. SAPO-34 crystals of 150 nm with a high surface area and microporosity were synthesized using dry-gel methodology. The PES/SAPO-34 membranes were optimized following previous work and used in a defined composition, using 5 or 10 w/w% of DES during membrane preparation. All MMMs were characterized by their ideal gas permeability using N2 and CO2 pure gasses. Selected membranes were also tested using CH4 pure gas. The results presented that 5 w/w%, in polymer mass, of ChCl-glycerol presented the best result over the synthesized membranes. An increase of 200% in CO2 permeability maintains the CO2/N2 selectivity for the non-modified PES/SAPO-34 membrane. A CO2/CH4 selectivity of 89.7 was obtained in PES/SAPO-34/ChCl-glycerol membranes containing 5 w/w% of this DES, which is an outstanding ideal separation performance for MMMs when compared to other results in the literature. FTIR analysis reiterates the presence of glycerol in the membranes prepared. Dynamic Mechanical Thermal Analysis (DMTA) shows that the addition of 5 w/w% of DES does not impact the membrane flexibility or polymer structure. However, in concentrations higher than 10 w/w%, the inclusion of DES could lead to high membrane rigidification without impacting the overall thermal resistance. SEM analysis of DES-enhanced membranes presented asymmetric final membranes and reaffirmed the results obtained in DMTA about rigidified structures and lower zeolite-polymer interaction with higher concentrations of DES.

Bioinspired Ultra‐Stretchable and Highly Sensitive Structural Color Electronic Skins

AbstractOrganisms possess remarkably adaptive ability to complex environments. For example, chameleons can alter their skin color to adapt to varying environments, which has inspired significant advances in bioinspired soft electronic skins (E‐skins), and their wide applications in wearable sensors, intelligent robots, and health monitoring. However, current bioinspired E‐skins face challenges in ultra‐stretchability, high sensitivity, and long‐term stability owing to the intrinsic limitations associated with their mismatched interface between soft matrix and hard conductive fillers, hindering their practical applications. Here, it is reported that bioinspired structural color electronic skins (SC E‐skins) that consist of liquid metal particles (LMPs), periodical ordered colloidal crystal arrays, and ultra‐stretchable hydrogel, imparting synergistic and durable electrical–optical sensing capabilities. Such SC E‐skins demonstrate outstanding performances including superior flexibility (elongation at break &gt; 1100%), high sensitivity (gauge factor = 3.26), fast synergetic electric–optical response time (≈100 ms), outstanding durability (over 1500 cycles), and high accuracy (R2 &gt; 99.5%). These bioinspired SC E‐skins with excellent capability of converting mechanical signals into synergetic electrical–optical outputs hold great promise for smart wearable devices, affording a new horizon in developing advanced health monitoring technologies.

Development of a novel Bi4Ti3O12/chitosan/rGO piezoelectric bio-composite for mechanical energy harvesting: Output energy optimization using response surface methodology modelling

This study focuses on the development of a novel 0–3 bio-piezoelectric composite utilizing bismuth titanate (Bi4Ti3O12) as the piezoelectric ceramic, chitosan as the polymer matrix, and graphene as a doping element. The primary objective of this study was to study the relationship between the mechanical, piezoelectric, and electrical properties within the developed 0–3 bio-piezoelectric composite. By systematically varying the weight percentages of bismuth titanate ceramic and graphene, our aim was to gain a comprehensive understanding of how these variations influence key properties such as young's modulus for flexibility, the piezoelectric coefficient d33, electrical conductivity, and voltage output. This exploration was driven by the recognition that these properties are interconnected and crucial for the performance of piezoelectric materials in practical applications. Response surface methodology (RSM) was specifically utilized to model the composite response, optimizing process variables through statistical and mathematical analyses. Through rigorous experimentation and modeling the optimal balance that maximizes conductivity, enhances piezoelectric performance, and ensures reliable voltage generation was determined. The optimum formula selected is the one prepared using a piezoelectric ceramic weight percentage of 35,07 %, and graphene weight percentage of 0.9 % for a harvested voltage equal to 12,05 V. The Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) Images of the optimized composite system revealed the uniform distribution of the fillers in the polymer matrix. The optimized composite design resulting from this systematic investigation holds significant promise for practical applications in energy harvesting and sensor technologies, aligning with the demands of Industry 4.0 and IoT technologies.

Experimental investigation the effect of bamboo micro filler on performance of bamboo-sisal-E-glass fiber-reinforced epoxy matrix hybrid composites

The numerous advantages of natural fiber reinforced hybrid composites, such as their light weight, biodegradability, recyclability, availability, and low cost, have brought them to the forefront for various structural applications in the automotive and aerospace industries. Aim of this study was to evaluate the impact of varying the weight fractions of bamboo micro filler on the tensile, flexural, impact, and water absorption properties of the Sisal-Bamboo-E-glass fiber reinforced epoxy matrix hybrid composite prepared by manual hand layup method. To enhance the bond between natural and synthetic fibers and reduce the hydrophilic nature of natural fibers, bamboo and sisal fibers were treated with 5 % NaOH for 6 and 8 h, respectively. The E-glass fiber content was kept constant at 10 %, while the weight fractions of sisal, bamboo fiber, epoxy matrix, and bamboo micro filler were varied. The bamboo micro filler size ranged from 75 to 100 μm. Tensile and flexural tests were conducted using a computer-controlled universal electromechanical testing machine, while impact testing was performed with a Charpy impact test machine. The results showed that the hybrid composite containing 15 % sisal, 10 % glass, 15 % bamboo fiber, 57 % epoxy, and 3 % bamboo micro filler exhibited the highest tensile strength (87 MPa),flexural strength (77 MPa), high impact energy (8.9 J) and high toughness (24.64 J/cm2). Conversely, the highest water absorption capacity was observed in composites with 6 % bamboo micro filler. Overall, the tensile, flexural, impact, and water absorption properties of the hybrid composites were significantly influenced by the weight fractions of the fibers and bamboo micro filler.

A Review of Advanced Thermal Interface Materials with Oriented Structures for Electronic Devices

In high-power electronic devices, the rapid accumulation of heat presents significant thermal management challenges that necessitate the development of advanced thermal interface materials (TIMs) to ensure the performance and reliability of electronic devices. TIMs are employed to facilitate an effective and stable heat dissipation pathway between heat-generating components and heat sinks. In recent years, anisotropic one-dimensional and two-dimensional materials, including carbon fibers, graphene, and boron nitride, have been introduced as fillers in polymer-based TIMs due to their high thermal conductivity in specific directions. The orientation of the fillers in the polymer matrix has become an important issue in the development of a new generation of high-performance TIMs. To provide a systematic understanding of this field, this paper mainly discusses recent advances in advanced oriented TIMs with high thermal conductivity (&gt;10 W/(m·K)). For each filler, its preparation strategies and enhancement mechanisms are analyzed separately, with a focus on the construction of oriented structures. Notably, there are few reviews related to carbon fiber TIMs, and this paper details recent research results in this field. Finally, the challenges, prospects, and future development directions of advanced TIMs are summarized in the hope of stimulating future research efforts.

The Input of Nanoclays to the Synergistic Flammability Reduction in Flexible Foamed Polyurethane/Ground Tire Rubber Composites.

Currently, postulated trends and law regulations tend to direct polymer technology toward sustainability and environmentally friendly solutions. These approaches are expressed by keeping materials in a loop aimed at the circular economy and by reducing the environmental burdens related to the production and use of polymers and polymer-based materials. The application of recycled or waste-based materials often deals efficiently with the first issue but at the expense of the final products' performance, which requires various additives, often synthetic and petroleum-based, with limited sustainability. Therefore, a significant portion of research is often required to address the drawbacks induced by the application of secondary raw materials. Herein, the presented study aimed to investigate the fire performance of polymer composites containing highly flammable matrix polyurethane (PU) foam and filler ground tire rubber (GTR) originating from car tire recycling. Due to the nature of both phases and potential applications in the construction and building or automotive sectors, the flammability of these composites should be reduced. Nevertheless, this issue has hardly been analyzed in literature and dominantly in our previous works. Herein, the presented work provided the next step and investigated the input of nanoclays to the synergistic flammability reduction in flexible, foamed PU/GTR composites. Hybrid compositions of organophosphorus FRs with expandable graphite (EG) in varying proportions and with the addition of surface-modified nanoclays were examined. Changes in the parameters obtained during cone calorimeter tests were determined, discussed, and evaluated with the fire performance index and flame retardancy index, two parameters whose goal is to quantify the overall fire performance of polymer-based materials.

Calcium Silicate Promoting the Upcycling Potential of Polysulfone Medical Waste in Load-Bearing Applications.

Polysulfone (PSF) medical waste can be effectively repurposed due to its excellent mechanical properties. Due to the increasing need for load-bearing bone implants, it is crucial to prioritize the development of biocompatible polymer-matrix composites. Calcium silicate (CaSi), known for its osteogenesis and antibacterial properties, is widely used in medical applications. In this study, recycled PSF plastics in fiber or nanoparticle forms and commercial PSF products were used to create PSF-based composites filled with three different amounts (10, 20, and 30 vol%) of CaSi. The green compact was heat-treated at various temperatures. Experimental results showed that the mechanical interlocking of the PSF matrix and CaSi filler occurred due to the liquefaction of PSF fibers or nanoparticles during heat treatment. When the composite contained 20% CaSi, the obtained three-point bending strength exceeded 60 MPa, falling within the reported strength of compact bone. There was a concurrent improvement in the biocompatibility and antibacterial activity of the PSF-based composites with the increasing amount of CaSi. Considering their mechanical properties and antibacterial activity, the 20% CaSi-containing PSF-based composites treated at 240 °C emerged as a promising candidate for bone implant applications. This study demonstrated the feasibility of upcycling medical waste such as PSF as a matrix, opening doors for its potential usage in the medical field.