Hybrid Fillers Research Articles

Synergistic effects of silane‐modified carbon black and nano‐silica hybrid fillers on the performance of natural rubber compounds

AbstractThis study investigates the efficiency of already developed surface‐modified carbon black (CB), both independently and in conjunction with nano‐silica, as a hybrid filler, to the properties of natural rubber (NR) compounds. The modification process, followed by coupling agent treatment, enhanced cross‐link density and curing characteristics, though the inclusion of nano‐silica alone negatively affected curing due to its inherent polarity and tendency to agglomerate. The filled compounds with modified CB exhibited significant improvements in mechanical properties, notably tear resistance. Moreover, the combination of nano‐silica with modified CB yielded compounds with superior tear resistance, attributed to synergistic effects. CB surface modification exhibited varying effects on the glass transition temperature, with enhancements observed in tan δ at lower temperatures, indicating improved ice and wet grip potential. Also, it reduced rolling resistance after treatment with a coupling agent. While thermal stability remained consistent across the studied compounds, swelling resistance varies with filler type and ratio. Thermodynamic analysis confirmed the positive impact of CB surface modification on the elasticity and chain mobility of the investigated rubber compounds. It was concluded that the strategic selection of fillers and modification approaches were essential for achieving optimal results in the rubber compound's performance and application.

Nanoscale brick and mortar strategy for mechanically strong multifunctional composites with extremely high filler-loading

To achieve the best physico-chemical properties of polymer composites, the concentration of fillers should be maximized in many cases. However, at extremely high concentrations of fillers, the discontinuity of the polymer matrix results in poor mechanical properties. To overcome this problem, we propose an efficient protocol to improve the mechanical strength significantly, even at an extremely high concentration of microscale fillers (graphite flakes, 95 wt%). Since the mechanical strength of the polymer composite strongly depends on both the homogeneous distribution of the polymer matrix around microscale fillers and the adhesion between them, we increased the mechanical strength of the composite by the preparation of a hybrid filler decorated with polymer nanoparticles. The decorated polymer nanoparticles eventually turned to the matrix during hot-pressing process like a mortar between bricks. Systematic studies on the mechanical strength as well as electrical and thermal conductivities of the composites revealed that both the precisely controlled size of the polymer nanoparticles and even distribution of them on the hybrid fillers were critical variables to enhance the material's properties above. The newly developed polymer composites with superior physical properties exhibited good electromagnetic interference shielding (EMI shielding effectiveness >80 dB in X-band, thickness ∼ 1.5 mm), making them suitable as electric heaters.

Enhanced thermal conductivity in thermoplastic polyether ester elastomer vitrimer composite foams via cell growth-induced orientation and lap of hybrid fillers

Lightweight thermal conductive polymer foams own a great potential application in some weight sensitive fields such as aerospace and encapsulation. Herein, the enhancement of thermal conductivity of thermoplastic polyether ester elastomer (TPEE) vitrimer composites foams caused by cell growth inducing fillers orientation and lap was investigated with hybrid fillers of fixed 15 vol% h-BN and various SiC nanowires. First, the hybrid fillers orientation in TPEE vitrimer composites (TVC) characterized by SEM and XRD patterns showed that the hybrid fillers were induced to be through-plane orientation and no interfacial defects were observed owing to the increasing contact area among fillers caused by large specific area and length of SiC nanowires. Based on that, cells were generated into TVC through scCO2 foaming. The effect of through-plane orientation and lap of hybrid fillers caused by cell growth of different cell structures on the thermal conductivity of TVC foams was investigated using extended Hashin-Shtrikman model and Maxwell-Eucken I model. The results showed that the thermal conductivity of TVC foams could greatly be enhanced to be higher than that of TVC by cell growth of continuous cell structures as it contributed to the through-plane orientation and lap of hybrid fillers to increase the contact and lap ratio among fillers. Thereby, the thermal conductive networks favorable to heat transfer were constructed in TVC foams to enhance the thermal conductivity as well as merit of lightweight.

Preparation of cellulose-PCC fibre hybrids: Use as filler in polypropylene (PP) composites

Abstract Polymer composite materials find application in various life sectors such as packaging, lightweight construction and the fabrication of medical devices. Functional fillers like mineral colloids, synthetic and natural fibres enable a precise tailoring of the mechanical properties of the resulting compounds. Precipitated calcium carbonate (CaCO3, PCC) has proven to be a special popular mineral polymer filler. From economic and ecologic reasons, it is desirable to increase filler contents in polymers while maintaining material strength. To achieve this, the present work has developed a hybrid filler system which is based on carboxymethylated, fibrillated cellulose fibres. CaCO3 is precipitated onto the fibres in a single step twin-screw extrusion process by the co-precipitation method. This process ensures a strong, permanent interaction between the fibres and the mineral particles, which enables CaCO3 contents in the filler of up to 68 wt.-%. The resulting hybrid fillers were compounded with polypropylene (PP) in a powder or paste state with filler contents between 5 wt.-% and 20 wt.-%. The resulting composites show an increase in the zero-shear viscosity and, in the event of sufficient network formation, a marked increase in stiffness was observed.

Nanocarbon‐Based Hybrid Fillers in Thermally Conductive Polymer Composites: A Review

With the broad commercialization of microelectronics, 5G communication, and new energy vehicles, the demand for polymer composites with high thermal conductivity (TC) increases. Carbon‐based nanomaterials have high TC, are of lightweight and low cost, and have been widely studied as thermally conductive fillers for composites. In this article, carbon‐based thermal conductive fillers in polymer composites are focused on. It summarizes the treatments of functionalization, directional arrangement, and dispersion of carbon‐based nanofillers. Moreover, from the perspective of nanocarbon, hybrid nanofillers are divided into three categories: carbon/carbon, carbon/ceramics, and carbon/metal for the first time, and the thermal conductive effect of these hybrid fillers is discussed. Finally, potential areas for future research and development of thermal interface materials are discussed.

Vertically interconnected structure enhances the thermal management capability of copper-based composites

Efficient thermal management relies on constructing a network structure. Here, we propose an efficient strategy for fabricating an in-plane vertically interconnected network by integrating copper nanoparticles and nanowires through electrospinning and vertically stacking hot-pressing. This approach offers a dual benefit: creating an in-plane vertically interconnected thermal conductive network while simultaneously protecting the fillers against oxidation. Furthermore, the combination of multi-dimensional hybrid fillers reduces interfacial thermal resistance. Thus, the (Cu NPs-Cu NWs)@PVP/PVA film with hybrid fillers achieves a high thermal conductivity of 22.71 Wm-1K-1, along with superior thermal stability, oxidation resistance, and flexibility, making it promising for advanced electronic device thermal management.

Building Efficient 3D Networks by Controlled Localization of Hybrid Fillers in Immiscible Polymer Blends

Building Efficient 3D Networks by Controlled Localization of Hybrid Fillers in Immiscible Polymer Blends

Structure and Properties of Polylactide Composites with TiO2-Lignin Hybrid Fillers.

The research presented in this article focuses on the use of inorganic-organic material, based on titanium dioxide and lignin, as a filler for polylactide (PLA) biocomposites. To date, no research has been conducted to understand the impact of hybrid fillers consisting of TiO2 and lignin on the supermolecular structure and crystallization abilities of polylactide. Polymer composites containing 1, 3 or 5 wt.% of hybrid filler or TiO2 were assessed in terms of their structure, morphology, and thermal properties. Mechanical properties, including tensile testing, bending, impact strength, and hardness, were discussed. The hybrid filler is characterized by a very good electrokinetic stability at pH greater than 3-4. The addition of all fillers led to a small decrease in the glass transition temperature but, most importantly, the addition of 1% of the hybrid filler to the PLA matrix increased the degree of crystallinity of the material by up to 20%. Microscopic studies revealed differences in the crystallization behavior and nucleation ability of fillers. The use of hybrid filler resulted in higher nucleation density and shorter induction time than in unfilled PLA or PLA with only TiO2. The introduction of small amounts of hybrid filler also affected the mechanical properties of the composites, causing an increase in bending strength and hardness. This information may be useful from a technological process standpoint and may also help to increase the range of applicability of biobased materials.

The Synergistic Effect of Carbon Black/Carbon Nanotube Hybrid Fillers on the Physical and Mechanical Properties of EPDM Composites after Exposure to High-Pressure Hydrogen Gas.

This study investigated the synergistic effect of carbon black/multi-wall carbon nanotube (CB/MWCNT) hybrid fillers on the physical and mechanical properties of Ethylene propylene diene rubber (EPDM) composites after exposure to high-pressure hydrogen gas. The EPDM/CB/CNT hybrid composites were prepared by using the EPDM/MWCNT master batch (MB) with 10 phr CNTs to enhance the dispersion of CNTs in hybrid composites. The investigation included a detailed analysis of cure characteristics, crosslink density, Payne effect, mechanical properties, and hydrogen permeation properties. After exposure to 96.3 MPa hydrogen gas, the hydrogen uptake and the change in volume and mechanical properties of the composites were assessed. We found that as the MWCNT volume fraction in fillers increased, the crosslink density, filler-filler interaction, and modulus of hybrid composites increased. The hydrogen uptake and the solubility of the composites decreased with an increasing MWCNT volume fraction in fillers. Moreover, after exposure to hydrogen gas, the change in volume and mechanical properties exhibited a diminishing trend with a higher MWCNT volume fraction. We conclude that the hybridization of CB and CNTs formed strong filler-filler networks in hybrid composites, consequently reinforcing the EPDM composites and enhancing the barrier properties of hydrogen gas.

Preparation of high thermal conductivity vat photopolymerization used UV-curable resin synergistically enhanced by silicon nitride and boron nitride

Additive manufacturing (3D printing) technologies, especially vat photopolymerization (VPP), provide a cost-effective and efficient approach for the fabrication of heat dissipation devices with complex geometric designs. The incorporation of inorganic thermal conductive fillers into resin matrix is widely recognized as an effective way to enhance thermal conductivity. Notably, the synergistic effect of hybrid fillers can further enhance thermal conductivity. However, the consequent drastic increase in viscosity of the UV-curable resin may decrease the success rate and accuracy of printing on commercial VPP 3D printers. In this work, hexagonal boron nitride (h-BN) platelets and spherical h-BN together with β-Si3N4 are introduced into the UV-curable resin system. Corresponding results proved that h-BN together with β-Si3N4 provide a synergistic effect on the thermal conductivity enhancement compared to the filler in single morphology only. Moreover, owing to the spherical structure, low-viscosity UV-curable resin with high solid content can be prepared. In specific, a thermal conductive polymer composite material with a solid content of 60 wt% is prepared, which exhibits high thermal conductivity (1.42 W/mK), representing an enhancement of up to 610 % compared to neat resin. In subsequent application demonstrations, 3D printed heat dissipation devices with as-prepared resin composite material have been shown to effectively enhance the heat dissipation rate for the heating device.

Enhanced dielectric constant and concurrently suppressed dielectric loss of PVDF composites incorporating BaTiO3@SSCNT@SiO2 core@double-shell structured fillers

Dielectric capacitor is an important component of power systems, but its low dielectric polarization and undesirable dielectric loss have still held back the development of miniaturized microelectronic devices. Hence, we reported core@shell structured fillers with a conducting material@insulating material double-shell to improve the dielectric performance of the poly (vinylidene fluoride) (PVDF) composites. The hybrid fillers introducing ultra-short carbon nanotube (SSCNT) as an inner layer between BaTiO3 (BT) as a core and silica (SiO2) as an outer shell were synthesized. As the thickness of the insulating shell is enough thin, the BT@SSCNT@SiO2/PVDF composites exhibit an enhanced dielectric constant and a concurrently suppressed dielectric loss with the decreasing thickness. The composite incorporating the filler with the thinnest SiO2 shell has the highest dielectric constant of 12.27 and the lowest dielectric loss of 0.023 at 20 wt% filler loading where the breakdown strength is about 15 less than the maximum value of 192.5 kV/mm. Furthermore, the hybrid fillers endow the composites with impressively stable dependence on frequency in a wide range of 102∼105 Hz. The achievement can be ascribed to the conducting property of the SSCNT inner layer and the suitable thickness of the insulating outer layer. They can synergetically provide the composites with an optimized polarization effect at a broad frequency resulting from the improved electrical field. This work reveals that a proper structure of the core@conducting material@insulating material core@double-shell filler can be an approach to optimize the overall dielectric performance of the polymer-based composites with high energy storage density.

Environmentally Friendly High‐Performance Polydimethylsiloxane Composites Reinforced with Renewable Cellulose Nanocrystals Based on Dynamic Silyl Ether Linkages

AbstractEnvironmentally friendly high‐performance composites made from either reprocessable polymer matrix or renewable fillers have become increasingly significant in order to reach a sustainable future. Herein, polydimethylsiloxane/modified cellulose nanocrystals (PDMS/mCNC) composites showing outstanding mechanical and reprocessable properties via silyl ether linkages are prepared. With only 1 wt% mCNC, the PDMS/mCNC composite exhibits the tensile strength of 2.96 MPa, which is twice that of the pure PDMS elastomer, while the toughness can achieve 7.32 MJ m−3. Remarkably, the reprocessing efficiency can be as high as 100% even for triple reprocessing process. Additionally, the favorable effect of mCNC on constructing hybrid filler network within vitrimers is explored for the first time. Selection of boron nitride nanosheet (BNNS) as the functional filler, 40 wt% BNNS is uniformly dispersed by only a small amount of mCNC and a homogeneous thermally conductive network is built, with the thermal conductivity of the PDMS/mCNC@BNNS composite increasing remarkably to 2.901 W m−1 K−1. In a word, this work paves the way to develop sustainable, mechanically strong, and reprocessable composites with mCNC as a renewable bio‐filler.

Structure and Properties of Epoxy Resin/Graphene Oxide Composites Prepared from Silicon Dioxide-Modified Graphene Oxide.

In this study, graphene oxide (GO) was modified via electrostatic interactions and chemical grafting by silica (SiO2), and two SiO2@GO hybrids (GO-A and GO-B, respectively) with different structures were obtained and carefully characterized. Results confirmed the successful grafting of SiO2 onto the GO surface using both strategies. The distribution of SiO2 particles on the surface of GO-A was denser and more agglomerated, while it was more uniform on the surface of GO-B. Then, epoxy resin (EP)/GO composites were prepared. The curing mechanism of EP/GO composites was studied by differential scanning calorimetry and in situ infrared spectra spectroscopy. Results of tensile tests, hardness tests, dynamic mechanical analysis, and dielectric measurement revealed that EP/GO-B exhibited the highest tensile properties, with a tensile strength of 79 MPa, a 43% increase compared to raw EP. Furthermore, the addition of fillers improved the hardness of EP, and EP/GO-B showed the highest energy storage modulus of 1900 MPa. The inclusion of SiO2@GO hybrid fillers enhanced the dielectric constant, volume resistivity, and breakdown voltage of EP/GO composites. Among these, EP/GO-B displayed the lowest dielectric loss, relatively good insulation, and relatively high volume resistivity and breakdown voltage. A related mechanism was proposed.

Robust, Self-Healing, and Multi-Use Poly(Urethane-Urea-Imide) Elastomer as a Durable Adhesive for Thermal Interface Materials.

Currently, research on thermal interface materials (TIMs) is primarily focused on enhancing thermal conductivity. However, strong adhesion and multifunctionality are also important characteristics for TIMs when pursing more stable interface heat conduction. Herein, a novel poly(urethane-urea-imide) (PUUI) elastomer containing abundant dynamic hydrogen bonds network and reversible disulfide linkages is successfully synthesized for application as a TIM matrix. The PUUI can self-adapt to the metal substrate surface at moderate temperatures (80°C) and demonstrates a high adhesion strength of up to 7.39 MPa on aluminum substrates attributed its noncovalent interactions and strong intrinsic cohesion. Additionally, the PUUI displays efficient self-healing capability, which can restore 94% of its original mechanical properties after self-healing for 6 h at room temperature. Furthermore, PUUI composited with aluminum nitride and liquid metal hybrid fillers demonstrates a high thermal conductivity of 3.87 W m-1 K-1 while maintaining remarkable self-healing capability and adhesion. When used as an adhesive-type TIM, it achieves a low thermal contact resistance of 22.1 mm2 K W-1 at zero pressure, only 16.7% of that of commercial thermal pads. This study is expected to break the current research paradigm of TIMs and offers new insights for the development of advanced, reliable, and sustainable TIMs.

Improving the thermal conductivity of an epoxy composite with chemically boron nitride-grafted carbon fiber

The rapid progress of electronic devices like electric vehicles, smartphones, and IoT systems has fueled the demand for compact, high-performance batteries. However, a critical challenge arises from heat accumulation within these devices, leading to malfunctions and reduced efficiency. To address this, efficient heat dissipation is crucial, with thermal interface materials (TIMs) widely used for heat transfer. While polymers are favored for TIMs due to their ease of processing and electrical insulation, their low thermal conductivity poses limitations. In this study, a solution is proposed by chemically grafting boron nitride (BN), a ceramic-based filler, onto carbon fiber (CF) surfaces. This BN-g-CF hybrid filler, formed through a reaction between acyl chlorides and amine groups, exhibits superior compatibility with polymer matrix. Characterization confirms successful treatment, and thermal conductivity measurements show a remarkable enhancement, positioning the BN-g-CF/epoxy resin composite as a promising solution for efficient thermal management in various electronic industries.

Effect of filler surface treatment on the physico-mechanical properties of filler/styrene-butadiene rubber nanocomposites

In the present work, the effects of various filler types and content on the characteristics and properties of styrene-butadiene rubber (SBR) were studied. This study prepared SBR filled with different fillers: kaolin, metakaolinite, synthetic zeolite Na-A, alumina (Al2O3) nanoparticles, and hybrid filler (synthetic zeolite Na-A/Al2O3). The silane coupling agent 3-aminopropyltriethoxysilane (APTES) was employed to treat the surface with fillers. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to determine the surface morphology. The results demonstrated that fillers improved the physicomechanical properties. Tensile strength and elongation at break (%) in composites containing synthetic zeolite Na-A increased by up to 158.6% at 3 phr and 100% at 2 phr, respectively. The results showed that the surface properties displayed by SEM analysis indicated a good distribution of filler particles. Also, the rubber compound’s resistance to organic solvents such as toluene was improved, as evidenced by swelling properties; the swelling ratio decreased by 17.5% while the crosslink density increased by 42.6% at 5 phr Al2O3/synthetic zeolite Na-A. The constants of the various hyperelastic models that explain the behavior of the composite materials under study were determined, and their predictions of the experimentally obtained stress-strain curves were compared. The study’s experimental findings will be helpful for several industrial uses, including an extender in water-based paints, rubber fillers, ceramic materials, paper fillers, and coating pigments.

Role of Copper Nanoparticles in the Thermal and Mechanical Properties of Expanded Graphite-Reinforced Epoxy Hybrids.

Epoxy resin is extensively applied in the electronics and electrical fields because of its outstanding comprehensive performance. However, the low thermal conductivity (TC) limits its application in thermal interface materials. In the present work, epoxy-based hybrid composites with high TC were prepared by using expanded graphite (EG) and copper (Cu) nanoparticles as thermally conductive hybrid fillers via hot blending and compression-curing processes. Additionally, the influence of the Cu content on the thermal properties, mechanical properties, and morphology of each epoxy/EG/Cu composite was investigated. According to the results, the epoxy/EG/Cu composite showed a maximum TC of 9.74 W/(m·K) at a fixed EG content of 60 wt % owing to the addition of 10 wt % Cu. After the addition of 10 wt % Cu, the flexural strength, flexural modulus, and impact strengths of epoxy/EG/Cu composites were improved from 27.9 MPa, 9.72 GPa, and 0.81 kJ/m2 to 37.5 MPa, 10.88 GPa, and 0.91 kJ/m2, respectively. Hence, this study offers a feasible strategy for the design of epoxy hybrid composites with excellent TC that can be applied to thermal interface materials.

Carboxymethyl Cellulose Based Biopolymer Electrolyte with Hybrid Fillers for Dye Sensitized Solar Cell

Carboxymethyl Cellulose Based Biopolymer Electrolyte with Hybrid Fillers for Dye Sensitized Solar Cell

Enhanced dielectric performance and thermal conductivity of the polyetherketoneketone composite films prepared via a facile template spray coating method

Polyetherketoneketone (PEKK) is a specialized engineering plastic renowned for its exceptional strength, high temperature resistance and chemical resistance. However, the high melting point of PEKK restricts its processing methods to traditional techniques such as melt extrusion, hot pressing, and molding, significantly limiting its application in the field of microelectronic devices. In this study, a facile template spray coating method was proposed to prepare highly flexible PEKK films. Furthermore, functionalized boron nitride-carbon nanotube (BN-CNT) hybrid fillers were prepared and incorporated into the PEKK matrix. The results demonstrated that when the content of BN-CNT hybrid filler was 5 wt%, the dielectric constant of the composite film ranges from 2.2 to 1.8 in the frequency range of 100–200000 Hz, with a dielectric loss value below 0.03. When the content of the hybrid filler increased to 20 wt%, the enhanced thermal conductive network results in a 640% increase in thermal conductivity compared to pure PEKK. The enhanced thermal conductivity of the composite films promoted heat dissipation of the computer CPU and accelerated the cooling rate. These findings demonstrate the great potential of the PEKK composite films for diverse applications in microelectronic devices.

Wear‐ and UV‐resistant polycarbonate‐based composite films reinforced by a novel inorganic–organic hybrid filler

AbstractAs one of the five major engineering plastics, polycarbonate (PC) has been applied in many industrial fields. However, its poor wear‐ and UV‐ resistance greatly limit its further promotion. Inspired by the dual benefits of inorganic–organic hybrid filler, in this study, we developed a novel type of catechol group‐ and nano silica‐containing reinforcing filler (CFNS) for the preparation of wear‐ and UV‐resistant PC‐based composite films. With a low level of filler content (1%), the coefficient of friction (COF) was distinctly reduced from 0.14 (neat PC film) to 0.06 (composite film), benefiting from a wear‐resistant surface layer. On the basis of ensuring high and stable transmittance for visible light, the composite films also exhibit strengthened capacity of UV shielding for the waveband from 293 to 400 nm. In addition, the general performance of composite films including tensile strength, tensile modulus, and thermal stability have also been improved in different degrees. Therefore, the composite films reinforced by CFNS are highly promising for a wide range of applications, ascribed to their improved general properties as well as two additional functions of wear‐ and UV‐resistance.