Hybrid Filler Loading Research Articles

Effect of graphene nanoplatelets and nano zinc oxide on gas barrier and antibacterial properties of thermoplastic nanocomposites

AbstractGraphene‐loaded thermoplastic nanocomposite films must be evaluated for antibacterial activity, mechanical, and barrier properties before being utilized as food packaging. Herein, economically feasible linear low‐density polyethylene (LLDPE)‐based flexible packaging materials were developed via the melt compounding technique at 170°C temperature by taking advantage of both graphene nanoplatelets (GNP) and nano zinc oxide (ZnO) fillers. Morphological studies reveal that in composites loaded with GNP/ZnO hybrid fillers, ZnO nanoparticles form a network‐like structure throughout the polymer matrix. Simultaneously, GNPs are uniformly dispersed. The inclusion of hybrid nanofiller considerably reduces both the oxygen transmission rate and the water vapor transmission rate (WVTR) in LLDPE nanocomposites. A maximum decrease of 36% and 67%, respectively, in both oxygen transmission rate and WVTR is observed for 3 wt% of hybrid filler loading in a thermoplastic matrix containing 1 wt% of nano ZnO. The antibacterial efficacy of the derived nanocomposite films is obvious against gram‐positive (Bacillus subtilis) and gram‐negative (Escherichia coli) bacterial strains. These nanocomposite films have the potential to be successfully utilized as flexible packaging materials owing to their improved thermal, barrier, and antibacterial effectiveness.Highlights GNP/ZnO was used as a hybrid reinforcing filler in the LLDPE matrix. ZnO nanoparticles establish a network‐like morphology. LLDPE nanocomposite films exhibited excellent antibacterial activity. Oxygen and water vapor barrier properties were significantly improved. The thermoplastic composite films could be used as food packaging materials.

Study the Effect of Hybrid Nanofillers Content on the X-ray Diffraction and Thermal Conductivity Properties of Epoxy-Based Nanocomposites

High-performance polymer nanocomposites utilizing different-sized nanofillers had a lot of interest recently. Due to their distinct structural, and thermal characteristics. Multi-wall carbon nanotubes (MWCNT) and nanoclay (NC) have the most interest among the numerous types of reinforcing as filler elements for a polymer. The formation of hybrid from MWCNT and NC at various loadings (0.5%, 1%, and 2wt%) on the characteristics of epoxy polymer have been assessed in this work. The specimens have been created using solution blending procedures with the addition of solvent ethanol at a ratio of 1:1 for dispersed nanofillers, and then they have been re-mixed with epoxy. Tests like X-Ray diffraction (XRD), and thermal conductivity were used to identify properties of epoxy. According to the test results, the thermal conductivity rise as the filler content rises at 1wt%, then start to decrease after 1wt%. The sample with the hybrid filler loading of 1 wt% produced the best performance. Since hybrid epoxy exhibits the best result of the thermal conductivity 135% over MWNT and NC nanocomposites of 1 wt.% reached 0.3568 W/m.K in the increased thermal conductivity property. By examining the EP nanocomposites XRD pattern. The hybrid of epoxy nanocomposites exhibits all of the NC and MWCNT characteristic peaks. Since interactions between the filler and the epoxy cause a shift in the peak location of 1wt%. Due to the homogeneity of the nanofillers entire epoxy matrix, there may be changes in the intensity or location of the peaks at 1% for 2θ= 20.13°, which corresponds to an interlayer distance of d=0.461nm.

Investigation of Mechanical and Thermal Stabilities of Tamarind Seed- and Peanut Shell Powder-Reinforced Vinyl Ester Composite

Efficient exploitation of agricultural waste results in a more sustainable and ecofriendly environment since it lessens the burden of their disposal, which has become increasingly important in recent times. Due to their high mechanical strength and high thermal stability, these biodegradable low-value agrosolid wastes have the potential to successfully replace synthetic fibers and fillers in polymer matrices in the form of reinforcements. This work deals with the addition of low-cost and renewable hybrid natural fillers, tamarind seed filler (TMS), and peanut shell powder (PNS) as particulate reinforcements to the vinyl ester (VE) resin. Traditional compression molding creates TMS/PNS-VE hybrid composites with filler loadings ranging from 5% to 30%. After the composites were fabricated, they were tested for strength properties and heat deflection temperature. A detailed experimental analysis of the mechanical properties was conducted. According to the findings, 20 wt.% hybrid filler loading to the vinyl ester polymer exhibited peak tensile, flexural, and impact strengths of 40.3 MPa, 142 MPa, and 16 kJ/m2, respectively, which is 1.52, 1.69, and 1.29 times the properties of the virgin polymer. However, the peak elongation at break 3.9% was obtained at 30 wt.%. Similarly, the heat deflection temperature (HDT) test of TMS/PNS-VE composites showed a maximum rise of 50.91% at 25 wt.% of filler loading. This is 1.51 times greater than the heat deflection temperature of the pure vinyl ester resin. The findings made it quite clear that adding 20 wt.% biosolid waste hybrid particulate fillers made out of tamarind seed and peanut shell to vinyl ester is the optimum weight, which improves the mechanical and thermal properties of the TMS/PNS-VE composite, making it suitable for making cost-effective materials for lightweight applications. This study also utilizes scanning electron microscopy (SEM) to investigate the microstructural characteristics of the composites, correlating these features with their mechanical performance.

Combination effect of functionalized high aspect ratio carbonaceous nanofillers and carbon black on electrical, thermal conductivity, dielectric and EMI shielding behavior of co-continuous thermoplastic elastomeric blend composite films

The utilization of conductive hybrid carbonaceous fillers to fabricate highly efficient electromagnetic interference (EMI) shielding materials has become a popular area of research interest recently. Here, we report the facile fabrication of lightweight thermoplastic elastomeric blend composite films by solution mixing technique, taking advantage of both the hybrid carbonic nanofillers (high aspect ratio carbon inclusion and conductive carbon black) and the co-continuous polystyrene (PS)/ethylene-co-methyl acrylate (EMA) blend. Combination of acid-functionalized multiwalled carbon nanotubes (f-CNT) and carbon nanofibers (f-CNF) with conductive Vulcan-XC 72 carbon black (VCB) aids in the more uniform dispersion of hybrid carbonaceous inclusion in this blend system. The selective location of hybrid nanofillers in EMA phase of binary polymer mix enhanced the electrical properties, thermal conductivity, and microwave shielding performance of the resultant blend composites by constructing a dense, co-supportive, double percolated conductive network throughout the blend. The effect of f-CNT or f-CNF concentration in hybrid composites on the above-mentioned properties of blend composites has been investigated in this work. The as-prepared PS/EMA/VCB/f-CNT and PS/EMA/VCB/f-CNF blend composite films exhibited a thermal conductivity of 0.81 and 0.83 W/m.K and absorption-dominated microwave shielding of -31 and -32.5 dB, respectively with 15 wt% hybrid filler loading containing 50 wt% of f-CNT or f-CNF. These conductive thermal management composite films could be excellent choices to mitigate EM pollution.

Enhancing thermal conductivity of epoxy composites via f‐BN@f‐MgO hybrid fillers assisted by hot pressing

AbstractHigh thermal conductive polymeric composites are extremely desired for the thermal management of electronic devices due to the rapid development of the modern microelectronic industry. Herein, the functionalized boron nitride (BN) and magnesium oxide (MgO) hybrid fillers (f‐BN@f‐MgO) were synthesized and used to prepare the enhanced thermal conductive epoxy (EP) composites through the hot‐pressing method. The results demonstrated that the covalent binding of BN and MgO in the hybrid fillers reduced the interface thermal resistance effectively between fillers and matrix and the hot‐pressing induced force facilitated the construction of the continuous thermal conduction paths. Consequently, the as‐prepared epoxy composite at 40 wt% hybrid fillers loading had high thermal conductivity (TC) (1.97 W/[m·K]), outstanding insulating performance (6.9 × 1015 Ω cm) and excellent thermal stability. Furthermore, a probable thermal conduction mechanism was proposed to illustrate the high TC of the epoxy composite. Therefore, this study provides a new approach to preparing epoxy composites with outstanding performances.

Effect of green hybrid fillers loading on mechanical and thermal properties of vinyl ester composites

AbstractThe need for eco‐friendly materials has been attracted due to renewability, abundance availability, low cost, and so on. Therefore, the search for bio fillers for the fabrication of bio‐based composite materials is gaining more and more attention in both academic and industry circles because it promotes sustainability. The present study represents the utilization of biomass solid waste in the hybrid form of Tamarind Seed and Date Seed Filler (TSF/DSF) into polymer reinforced composite which has been explored for the first time by a compression molding technique. These fillers are bio‐waste that can be obtained at a minimal cost from renewable sources. An attempt has been made to use these hybrid fillers to reinforce the matrix ranging from 0 to 50 wt%, and their physical, mechanical, and thermal properties were investigated. In general, the inclusion of hybrid fillers increases mechanical properties, although the addition of hybrid fillers had only a minor impact on thermal properties. When compared to the pure vinyl ester resin, the hybrid fillers reinforced composites revealed a significant enhancement in tensile, flexural, impact, and hardness properties, with improvements of 1.51 times, 1.44 times, 1.87 times, and 1.46 times respectively, at 10 wt% filler loading. Filler matrix interaction of fractured mechanical testing samples was evaluated by scanning electron microscope. Based on the findings, hybrid filler reinforced composites may be suitable for applications where cost is a consideration and where minor compromises in thermal qualities are acceptable.

Highly Thermally Conductive Epoxy Composites with AlN/BN Hybrid Filler as Underfill Encapsulation Material for Electronic Packaging.

In this study, the effects of a hybrid filler composed of zero-dimensional spherical AlN particles and two-dimensional BN flakes on the thermal conductivity of epoxy resin were studied. The thermal conductivity (TC) of the pristine epoxy matrix (EP) was 0.22 W/(m K), while the composite showed the TC of 10.18 W/(m K) at the 75 wt% AlN–BN hybrid filler loading, which is approximately a 46-fold increase. Moreover, various essential application properties were examined, such as the viscosity, cooling rate, coefficient of thermal expansion (CTE), morphology, and electrical properties. In particular, the AlN–BN/EP composite showed higher thermal stability and lower CTE (22.56 ppm/°C) than pure epoxy. Overall, the demonstrated outstanding thermal performance is appropriate for the production of electronic packaging materials, including next-generation flip-chip underfills.

Vertically Aligned Silicon Carbide Nanowires/Boron Nitride Cellulose Aerogel Networks Enhanced Thermal Conductivity and Electromagnetic Absorbing of Epoxy Composites

HighlightsCellulose aerogel with vertically oriented structure was obtained by constructing a vertically aligned SiC nanowires/BN network via the ice template assisted strategy.The thermal conductivity of the composite in the vertical direction reaches 2.21 W m−1 K−1 at a low hybrid filler loading of 16.69 wt%, which was increased 890% compared to pure epoxy.The composite exhibits good electrically insulating with a volume electrical resistivity about 2.35×1011 Ω cm, and displays excellent electromagnetic wave absorption performance.

High thermal conductivity of boron nitride filled epoxy composites prepared by tin solder nanoparticle decoration

To achieve a high thermal conductivity, thermally conductive polymer composites have been recently exploited, focusing on connecting a 3D network of thermally conductive fillers by applying external pressure or constructing a pre-made 3D filler framework to reduce phonon scattering within the polymer matrix. However, these approaches severely restrict the use of polymers, particularly epoxy composites, in many commercial applications such as the thermal management of electronic device packaging. In this study, a high-thermal-conductivity epoxy composite is fabricated by incorporating hexagonal boron nitride ( h -BN) decorated with tin nanoparticles (Sn NPs). Under a hybrid filler (Sn NPs on h -BN) loading (68 wt %), the composite exhibits a high thermal conductivity of 11.9 ± 0.29 W m −1 K −1 while maintaining a relatively low dielectric constant (D k ∼ 7.52) and loss (D f ∼ 0.023) at 1 MHz with a coefficient of thermal expansion of 34 ppm °C −1 . The Sn NPs on h -BN in the epoxy resin matrix are thermally percolated by the in-situ growth of Sn NPs under carefully controlled curing temperature and time, resulting in significantly improved thermal conductivity of the epoxy composite under pressure-less curing conditions.

Enhanced dielectric response of ternary polymeric composite films via interfacial bonding between V2C MXene and wide-bandgap ZnS

Increasing the dielectric constant of polymer/sulfide ceramic composites by using wide-bandgap semiconducting sulfide ceramic fillers like ZnS is difficult because of their low interface polarization. To increase the dielectric constant, in this study, ternary polymer-based composite films were designed and fabricated using a hybrid filler consisting of shell-like ZnS particles and core-like V2C MXene particles. First, V2C MXene with a multi-layered structure was synthesized from the simplest raw materials followed by the in-situ hydrothermal growth of ZnS particles around the V2C particles. Then, binary polymer/ZnS and ternary polymer/V2C–ZnS composites were fabricated, and their dielectric, conductive, and electrical breakdown properties were investigated. Finally, the effect of interfacial bonding between the V2C and ZnS phases was investigated by density functional theory calculations, and the contribution of V2C/ZnS interfacial bonding to the higher dielectric constant of the ternary composites than that of the binary composites was explained. The ternary composites exhibited balanced electrical properties suitable for energy storage applications. The ternary composite with 10 wt% hybrid filler loading exhibited a high dielectric constant of ~52, a low dielectric loss of ~0.11 at 100 Hz, and a high electrical breakdown strength of ~202 MV m−1. This study paves the way for the facile fabrication of high-performance composite dielectrics for application in advanced capacitors.

Tribological characterization of pultruded hybrid glass-jute fibre reinforced plastic composites from room temperature to 75°C

The aim of the present study is to find the tribological properties of newly developed polyester-based hybrid glass-jute fibre reinforced plastic composites loaded with different weight per cent of hybrid filler particles were investigated under a dry sliding medium from room temperature to 75°C.,The study was carried out using a pin-on-disc wear test set-up. The design of experiments was carried out in a controlled way using a central composite design based on response surface methodology to observe the effect of various parameters i.e. sliding velocity, sliding distance, the temperature of counterface and different applied load conditions during dry-sliding.,The maximum wear resistance was found at 9 Wt% loading of filler, 4 ms-1 sliding velocity, 30 N applied load, 54°C temperature of the counterface and 1,100 m sliding distance condition. Optimum values of hybrid filler loading, sliding velocity, applied load, the temperature of the counterface and sliding distance for the minimum coefficient of friction value and minimum friction force are 9 Wt%, 4 ms−1, 30 N, 54° C, 1,100 m and 12 Wt%, 3 ms−1, 20 N, 59°C and 1,100 m, respectively. The worn surface morphology was studied using scanning electron microscope, for wear dominant mechanisms.,The tribological properties of newly developed polyester-based hybrid glass-jute fibre reinforced plastic composites loaded with different weight % of hybrid filler particles, were investigated under dry sliding medium from room temperature to 75°C has not been attempted yet.

Biocompatible, Electroconductive, and Highly Stretchable Hybrid Silicone Composites Based on Few-Layer Graphene and CNTs.

In this paper, we report a cost-effective and scalable approach to produce highly homogeneous graphene and CNT-based silicone composites with potential applications in diverse fields of research, including biosensors and wearable electronics. This approach includes the fabrication of hybrid fillers based on few-layer graphene and CNTs by water solution blending and manufacturing of graphene/CNT/PDMS composites through calendering in a three-roll mill. The influence of processing parameters, the graphene/CNT ratio, and hybrid filler loading was thoroughly investigated, and the optimal parameters for producing hybrid composites with superior electrical and mechanical properties were found. It was also confirmed that the graphene/CNT hybrid system exhibits a synergistic effect of non-covalent interactions between graphene sheets and CNT sidewalls. This synergistic effect prevents the aggregation of graphene sheets, facilitates the dispersion of graphene and CNTs in the silicone matrix, and contributes to the superior properties of hybrid composites compared to composites with either of these fillers alone.

Nonisothermal Kinetic Degradation of Hybrid CNT/Alumina Epoxy Nanocomposites

Due to the synergistic effect that occurs between CNTs and alumina, CNT/alumina hybrid-filled epoxy nanocomposites show significant enhancements in tensile properties, flexural properties, and thermal conductivity. This study is an extension of previously reported investigations into CNT/alumina epoxy nanocomposites. A series of epoxy composites with different CNT/alumina loadings were investigated with regard to their thermal-degradation kinetics and lifetime prediction. The thermal-degradation parameters were acquired via thermogravimetric analysis (TGA) in a nitrogen atmosphere. The degradation activation energy was determined using the Flynn–Wall–Ozawa (F-W-O) method for the chosen apparent activation energy. The Ea showed significant differences at α > 0.6, which indicate the role played by the CNT/alumina hybrid filler loading in the degradation behavior. From the calculations, the lifetime prediction at 5% mass loss decreased with an increase in the temperature service of nitrogen. The increase in the CNT/alumina hybrid loading revealed its contribution towards thermal degradation and stability. On average, a higher Ea was attributed to greater loadings of the CNT/alumina hybrid in the composites.

Study of mechanical properties of pultruded jute-glass reinforced unsaturated polyester bio-composites with hybrid filler loading

Purpose The purpose of this study is to develop jute-glass hybrid fibre reinforced polyester-based bio-composites using an indigenously developed pultrusion set-up and to present a detailed discussion on their mechanical characterization. Design/methodology/approach The work was carried out to observe the hybridization effect of natural and synthetic fibres in combination with hybrid fillers loading mainly on strength and other properties. The used hybrid fillers were a combination of 9 Wt.% of carbon black%, 6 Wt.% of eggshell ash powder and 6 Wt.% of coconut coir ash powder. A lab-based developed pultrusion set-up was used to develop these hybrid GJFRP composites of 1,500 mm length. The developed composites were tested for tensile strength, compressive strength and impact strength. Findings The maximum tensile, compressive and impact strength obtained are 88.37 MPa, 56.13 MPa and 731.91 J/m from 9 Wt.%, 9 Wt.% and 0 Wt.% of hybrid fillers loading, respectively. Breaking energy was found maximum as 7.31 J in hybrid glass-jute hybrid fibre reinforced plastic composites with no filler loading and it was observed that filler loading was decreasing the impact strength of developed hybrid composites. Shrinkage and its variations in the diameter of the finally developed cylindrical shape composites were observed after cooling and solidification. Scanning electron microscopy was used to observe the internal cracks, bonding of fibres and resin, voids, etc. Originality/value Development of hybrid filler based novel eco-friendly bio-composites and its experimental investigation on the impact strength, tensile strength and compressive strength has not been attempted yet.

Promoting healing progress in polymer composites based on Diels‐Alder reaction by constructing silver bridges

Polymer composites with self‐healing ability are highly desired for applications in advanced modern devices. Here, we report on self‐healing polymer composites consisting of silver deposited‐carbon nanotubes hybrid nanoparticles (CNT‐Ag) as fillers and self‐healable polyurethane (DAPU) as a matrix based on thermally reversible Diels‐Alder reaction. The results indicated that as the hybrid filler loading is 1 wt%, the composites not only obtained a high‐strength (~15.97 MPa) and high healing efficiency (~90.1%) by increasing filler loading after healing, but also enhance thermal conductivity (~1.65 Wm−1 K−1) and obviously shorten its healing progress in comparison with other composites in the case of the same healing time. Given that Ag_NPs deposited on the surfaces of the CNTs act as bridges to link the adjacent CNTs and reduce interfacial thermal resistance, which can effectively explain the reasons for the obtained high mechanical strength and healing efficiency and promoting healing progress in the polymer composites. This work may offer a novel strategy for balancing relation between mechanical property, healing ability and healing progress in the field of self‐healing materials application.

Effect of hybrid multi-walled carbon nanotube and montmorillonite nanoclay content on mechanical properties of shape memory epoxy nanocomposite

In this study, the hybrid nanofiller of montmorillonite (MMT) and multi-walled carbon nanotube (MWCNT) were incorporated into shape memory epoxy (SMEP) at different loadings. The fillers were dispersed in the SMEP resin by sonication. Tensile and flexural properties were analyzed at room temperature (RT) and high temperature (HT). Field emission scanning electron microscopy (FE-SEM) was used to analyze the microstructure of fractured samples. The tensile results revealed that at RT, the hybrid filler nanocomposite exhibits a ductile behavior meanwhile at HT, the nanocomposite exhibits a brittle behavior. The sample with the hybrid filler loading of 3 wt% MMT and 1.0 wt% MWCNT produced maximum performance with an increase of 32.5% in the ultimate tensile strength (UTS) and 20.9% in Young’s modulus at RT. The trends of the UTS and modulus obtained in the HT tensile test were almost similar to the RT tensile test despite yielding lower value. The RT flexural test revealed an increasing flexural strength as the filler loading increased with a maximum of 176% increase for hybrid filler of 3 wt% MMT and 1.0 wt% MWCNT. This trend was also observed for the flexural strength at HT. From FE-SEM, it was observed that the SMEP nanocomposite containing 3 wt% MMT and 1.0 wt% MWCNT was well dispersed and interact with each other, producing a synergetic reinforcement towards the performance. This study demonstrates the tensile and flexural reinforcement effect of MMT and MWCNT hybrid nanofiller. Findings from this study can be utilized to select the optimum loading for mechanical requirements in various applications.

Epoxy composite with significantly improved thermal conductivity by constructing a vertically aligned three-dimensional network of silicon carbide nanowires/ boron nitride nanosheets

The trend of miniaturization, integration and multi-function of modern electronics leads to the speedily increased power density which makes heat dissipation a crucial issue. Herein, epoxy based composites with highly enhanced through-plane thermal conductivity were successfully prepared by constructing a free-standing and vertically aligned silicon carbide nanowires (SiCw)/functionalized boron nitride nanosheets (f-BNNS) framework through modified filtration strategy. The synergetic effect between hybrid fillers ensured highly efficient channels for phonons in vertical direction that the maximum thermal conductivity reached 4.22 W/mK at a low hybrid filler loading of 21.9 vol%, increased by 1658% in comparison to that of pure epoxy. Due to the entanglement effect of SiCw/f-BNNS framework and the enhanced interface interaction by BNNS modification, the interfacial thermal resistance between filler/filler and filler/matrix were both reduced a lot compared with random dispersion method. Exceptional heat dissipation capability of the vertically orientated architecture was also demonstrated by theoretical simulation and chip encapsulation applications. In addition, the coefficient of thermal expansion of composite reached as low as 41.1 ppm/°C, only half of the epoxy resin (83.5 ppm/°C). This work provides a novel strategy for fabricating polymer based composites with superior through-plane thermal conductivity in thermal management applications.

Morphological, mechanical and thermal properties of PA6 nanocomposites Co-Incorporated with Nano-Al2O3 and graphene oxide fillers

In this paper, the surface hydroxylation modification of nano-alumina (nano-Al2O3) to result nano-Al2O3–OH and the chemical modification of graphene oxide (GO) by using silane coupling agent to produce GO-KH560 were first carried out respectively, followed by solution compounding to synthesis a novel three-dimensional functional hybrid filler (nano-Al2O3–OH/GO-KH560), and then polyamide 6 (PA6)/nano-Al2O3–OH/GO-KH560 (abbreviated as P-A-OH-G-KH560) thermally conductive nanocomposites were fabricated by melt blending technique and investigated for its morphological, mechanical and thermal properties. Morphological characterization revealed better dispersion of nano-Al2O3 and GO in the PA6 nanocomposites, which is attributed to the improved interfacial interaction between the PA6 and hybrid fillers. Loading of the hybrid fillers in the PA6 nanocomposites resulted in the significant improvement in mechanical properties such as tensile strength and elastic modulus and this effect is more pronounced on the increasing the hybrid fillers loading amount, when compared to the PA6 and pristine nano-Al2O3 filled system. Differential scanning calorimetric analysis showed that the crystallization of the PA6 nanocomposites was improved. The thermal conductivity of the P-A-OH-G-KH560 (100/5/0.8) nanocomposite increased by 86.13% compared with that of pure PA6. In summary, PA6 nanocomposites with fairly good mechanical and thermal conductivity are obtained at low filler contents.

Size-controlled graphite nanoplatelets: thermal conductivity enhancers for epoxy resin

Graphite nanoplatelets (GNPs) are outstanding thermal conductive fillers due to their unique crystal structure which consists of layered graphene formed by sp2-hybridized carbon atoms, but their preparation process is time-consuming. Herein, a high-efficiency and low-cost method is developed to prepare GNPs with controlled size without destroying their crystal structure. GNPs with an average size around 20 μm are obtained by a facile nitric acid treatment within 0.5 h, and 1–5 μm GNPs are produced by controlling ultrasonic time within 6 h in cheap commercial detergent. In addition, thermal network is fabricated by combining ~ 20 μm GNPs with 1–5 μm GNPs in epoxy. The existing researches have qualitatively demonstrated that hybrid carbon fillers with obvious size differences can enhance the thermal conductivity of epoxy through size synergistic effects, but rare quantitative studies pay attention to optimize size synergistic effects. This work demonstrates that different degrees of size synergistic effects can be achieved by tuning the size of small-sized GNPs, the proportion of different sized GNPs and the content of hybrid fillers. The results show that when the hybrid filler loading is 20 wt% and the ratio of ~ 20 μm GNPs to 1.82 μm GNPs is 17:3, the composite produces the optimal size synergistic effect and thermal conductivity reaches 1.33 W/m K, increased by 739% over neat epoxy. This composite has promising application in the thermal management areas due to its high thermal conductivity and economic competitiveness.

Enhanced thermal conductivity of microencapsulated phase change materials based on graphene oxide and carbon nanotube hybrid filler

Large energy storage capacity and high thermal charging/discharging rate are crucial for microencapsulated phase change materials (MEPCM) in thermal energy storage application. The microcapsules with dodecanol core and melamine-formaldehyde (MF) resin shell modified by graphene oxide (GO) and carbon nanotube (CNT) hybrid filler were prepared via in-situ polymerization. The effect of the combination of GO and CNT on morphology and thermal properties of the microcapsules was investigated, and the mechanism for heat transfer enhancement was further studied from both macroscopic and microscopic views. The results indicated that the addition of GO and CNTs largely enhanced the thermal conductivity of the microcapsules, and the GO-CNT hybrid filler was superior to individual GO or CNT. Particularly, with a hybrid filler loading of 0.6 wt%, the thermal conductivity of the microcapsule was improved by 195% with the latent heat slightly decreased. The prepared microcapsules were dispersed into water to form a latent functional thermal fluid, and its photo-thermal conversion performance was studied. The excellent thermal properties and photo-thermal conversion performance made the microcapsule dispersed slurry a potential fluid in direct absorption solar collectors.