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Different chemical treatment methods were employed to modify the surface of cotton stalk fibers, which were then utilized as fillers in composite materials. These treated fibers were incorporated into polylactic acid/polypropylene melt blends using the melt blending technique. Results indicated that increasing the surface roughness of cotton stalk fibers could enhance the overall mechanical properties of the composite materials, albeit potentially leading to poor fiber–matrix compatibility. Conversely, a smooth fiber surface was found to improve compatibility with polylactic acid, while Si-O-C silane coating increased fiber regularity and interfacial interaction with the matrix, thereby enhancing heat resistance. The mechanical properties and thermal stability of the composite materials made from alkali/silane-treated fibers exhibited the most significant improvement. Furthermore, better dispersion of fibers in the matrix and more regular fiber orientation were conducive to increasing the overall crystallinity of the composite materials. However, such fiber distribution was not favorable for enhancing impact resistance, although this drawback could be mitigated by increasing the surface roughness of the reinforcing fibers. [ABSTRACT FROM AUTHOR]

Polymer nanocomposites, which combine the advantages of polymers and fillers, are widely used in the field of automobile and aviation. Polyimine (PI) is an emerging thermoset material with remarkable properties, such as malleability, recyclability, and self-healing. Silicon carbide nano-whiskers (SiCw), as a cheap and high-hardness filler material, are chosen to enhance the properties of polyimine matrix. Silicon carbide nano-whisker-reinforced polyimine (PI-SiCw) nanocomposites were successfully fabricated by heat pressing, which was confirmed by FTIR and XPS tests. According to the results of mechanical tests, the mechanical properties of PI-SiCw nanocomposites were obviously improved. For example, with the addition of 0.5% SiCw, bending strength and bending elongation at break can be simultaneously increased by 33% and 148%, respectively. Surprisingly, the impact strength of PI-SiCw nanocomposites with 2% SiCw was increased by 154% compared to the matrix. SEM and EDS tests showed that the evenly distributed SiCw in the polyimine matrix enhanced the mechanical properties of PI-SiCw nanocomposites according to the mechanism of whiskers pulling out and the bridging principle. According to the TGA test results, the PI composites with SiCw retain a higher weight percentage at 800 °C. The reason was the combined effect of the good thermal stability of SiCw and their strong interactions with the PI matrix. As a result, introducing SiCw into the PI matrix imparts a slight improvement in thermal stability. This article presents an avenue of cost-effective research to enhance the mechanical properties of polyimine composites. [ABSTRACT FROM AUTHOR]

It is essentially important to develop durable polymer foams for services in high-temperature conditions. The current study reported the preparations and properties of a high-performance benzoxazine-phthalonitrile (BZPN) foam by utilizing azodicarbonamide and tween-80 as the blowing agent and stabilizer, respectively. Rheological and curing studies indicated that the appropriate foaming temperature for BZPN foam is below 180 °C, and its foaming viscosity window is below 20 Pa·s. Guided by these results, uniform millet bread-like BZPN foams with decimeter leveling size were successfully realized, suggesting the high prospect of large-scale production. The structural, mechanical, and thermal properties of BZPN foams were then investigated in detail. BZPN foam involves a hierarchical fracture mechanism during the compressive test, and it shows a high compression strength of over 6 MPa. During a burning test over 380 °C, no visible smoke, softening, or droplet phenomena appeared and the macroscopic structure of BZPN foam was well maintained. Mechanically robust, flame-retardant, and uniform large-size BZPN foam are promising light durable materials with high service temperatures, i.e., as filling materials even in a very narrow pipette. [ABSTRACT FROM AUTHOR]

Poly(L-lactide) (PLLA) is a promising candidate as a bioplastic because of its non-toxicity and biodegradability. However, the low flexibility of PLLA limits its use in many applications. Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-b-PEG-b-PLLA) block copolymer is of interest for bioplastic applications due to its superior flexibility compared to PLLA. The aim of this work is to modify PLLA-b-PEG-b-PLLA using a low-cost calcium carbonate (CaCO3) filler to improve material properties compared to PLLA/CaCO3 composites. The addition of CaCO3 enhanced the crystallinity and thermal stability for the PLLA-b-PEG-b-PLLA matrix but not for the PLLA matrix, as determined by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and thermogravimetric analysis (TGA). Phase morphology investigation using scanning electron microscopy (SEM) revealed that the interfacial adhesion between PLLA-b-PEG-b-PLLA and CaCO3 was stronger than between PLLA and CaCO3. Additionally, tensile testing was carried out to determine the mechanical properties of the composites. With the addition of CaCO3, the tensile stress and Young's modulus of the PLLA-b-PEG-b-PLLA matrix were increased, whereas these properties of the PLLA matrix were significantly decreased. Thus, CaCO3 shows great promise as an inexpensive filler that can induce nucleation and reinforcing effects for PLLA-b-PEG-b-PLLA bioplastics. [ABSTRACT FROM AUTHOR]

As one of the emerging nanomaterials, boron nitride nanotubes (BNNTs) provide promising opportunities for diverse applications due to their unique properties, such as high thermal conductivity, immense inertness, and high-temperature durability, while the instability of BNNTs due to their high surface induces agglomerates susceptible to the loss of their advantages. Therefore, the proper functionalization of BNNTs is crucial to highlight their fundamental characteristics. Herein, a simplistic low-cost approach of BNNT surface modification through catechol-polyamine (CAPA) interfacial polymerization is postulated to improve its dispersibility on the polymeric matrix. The modified BNNT was assimilated as a filler additive with AlN/Al2O3 filling materials in a PDMS polymeric matrix to prepare a thermal interface material (TIM). The resulting composite exhibits a heightened isotropic thermal conductivity of 8.10 W/mK, which is a ~47.27% increase compared to pristine composite 5.50 W/mK, and this can be ascribed to the improved BNNT dispersion forming interconnected phonon pathways and the thermal interface resistance reduction due to its augmented compatibility with the polymeric matrix. Moreover, the fabricated composite manifests a fire resistance improvement of ~10% in LOI relative to the neat composite sample, which can be correlated to the thermal stability shift in the TGA and DTA data. An enhancement in thermal permanence is stipulated due to a melting point (Tm) shift of ∼38.5 °C upon the integration of BNNT-CAPA. This improvement can be associated with the good distribution and adhesion of BNNT-CAPA in the polymeric matrix, integrated with its inherent thermal stability, good charring capability, and free radical scavenging effect due to the presence of CAPA on its surface. This study offers new insights into BNNT utilization and its corresponding incorporation into the polymeric matrix, which provides a prospective direction in the preparation of multifunctional materials for electric devices. [ABSTRACT FROM AUTHOR]

Good cementing properties, fast setting and strong thermal performance make calcium aluminate a valuable raw material for use in the production of different types of new refractory materials, e.g., heat conductive/storage materials. The main aim of the study was to determine thermal properties of novel Nb-slag based materials with different fillers, and to clarify the optimal composition and technology. The preparation process of the studied materials was the following: mixing of components, casting into moulds and hardening of materials. To estimate potential application areas, the following thermal properties of CA-based materials were investigated: thermal behaviour, the coefficient of thermal expansion (CTE) and conductivity. For thermal analysis, small cylindrical specimens were cut out from produced materials, and plates sized 25 × 300 × 300 mm were used for conductivity studies. Different compositions of CA-based materials, the hardening process, and the influence of mechanical activation on the strength were analysed. The best thermal properties similar to the analogous reference materials were obtained by quartz sand and granite sand as filler materials. The thermal conductivity of the novel CA-based material is 1.5 times higher and the bending strength is about 3 times higher compared to commercial thermoplates. [ABSTRACT FROM AUTHOR]

Boron nitride nanosheet (BNNS) and graphene oxide (GO) as a single filler can effectively improve the thermal conductivity of the composites, and the synergistic mechanism of BNNS and GO was investigated in this paper. In this study, BNNS was first surface-functionalized and the multi-sized (50 nm, 200 nm, 500 nm) modified BNNS (A-BN) were attached to GO through non-covalent bonding interactions to form a cross-linked structure. Then, A-BN and GO were used as thermal fillers and support material adsorption eutectic phase change materials (PCMs) to prepare composite phase change material (CPCM). Characterization results show that small-size A-BN was more likely to form dense thermal networks with good compatibility and interface connectivity between PCMs, A-BN, and GO, ensuring that PCMs can be stored in the network without leaking. When the size of the BNNS was greater than 200 nm, the advantage of thermal conductivity obtained by A-BN was no longer obvious, and the phase change behavior of CPCM was inhibited. In general, the prepared CPCM has the ideal thermal response and thermal stability, which is very suitable for energy storage and thermal management applications. [ABSTRACT FROM AUTHOR]

Biomass densification, which is also known as briquetting of sawdust and other agro residues, has been practiced for many years in several countries. The purpose of the present study was to produce fuel briquettes using heat-dried bagasse and to improve their physical properties and thermal value through using varying proportions of bagasse powder as the filler material and lignin as the natural binder. The results showed that lignin had a significant desirable effect on the entire properties of the prepared briquettes. In contrast, as a cellulose-based filler, bagasse powder was also able to significantly improve the thermal energy of the briquettes through increasing the briquettes’ density and mitigating porosity and moisture content. On this basis, according to the obtained results it can be stated that the process of heat-drying, using lignin as the binding element, and using cellulose-based powders, such as bagasse, as the filler are all suitable alternatives to increase the energy yielded by briquettes biomasses. [ABSTRACT FROM AUTHOR]

Biochar has emerged as a filler material for bio-degradable composites with favorable thermal and mechanical properties. Therefore, biochar is used in poly (lactic acid) (PLA) and PLA/thermoplastic starch (TPS) based composites. The crystallization and thermo-analytical properties of these blends with increasing amounts (20 to 50 wt%) of biochar are investigated. In the thermogravimetric analysis, the PLA/char composites' onset degradation temperature and temperature of maximum weight loss decrease with increasing biochar concentrations (320 to 275 °C and 380 to 350 °C, respectively). Contrastingly, in the PLA/TPS/char composites, the impact of the biochar is shielded by the TPS. The unaltered glass transition demonstrates that biochar does not act as a plasticizer in any of the composites, while TPS does. Biochar acts as a nucleation agent, but hinders further crystal growth at high concentrations, as confirmed by isothermal crystallization and infrared spectroscopy. The TPS smoothens the PLA/biochar interface, leading to an obstructed nucleation effect of biochar, proven by differential scanning calorimetry, infrared spectroscopy, and scanning electron microscopy. This work demonstrates the shielding effect TPS has on biochar and can help to understand further and optimize the production and biodegradability of these composites. [ABSTRACT FROM AUTHOR]

The high specific stiffness materials are used to design the space payload components. These components should sustain the extreme environmental condition throughout their life cycle without failure. The prerequisites of future space missions need lightweight materials which must be mechanically strong and high thermal and electrically conductive. The Carbon Nanotubes (CNTs) are efficient filler material in composite or metal matrix to enhance greater electrical and thermal conductivity. The quality of the CNT nano composite relies upon several parameters like the types of CNTs, its purity, aspect ratio, amount of loading, alignment, and interfacial adhesion between the nanotube and polymer. The performance of the CNT-CFRP composite depends on the successful execution of the processing technique. This review paper intends to highlight the enhancement of the mechanical, thermal, electrical properties of the composite, and the challenges to achieving it. This review paper helps to optimise the process parameters to fabricate Space Payload Components, required to replace existing high-density Space Qualified Materials. This review paper should help optimize the process parameters to fabricate Space Payload Components, which can be excellent alternatives to the existing high-density Space Qualified Materials without making any compromise on the performance index. [ABSTRACT FROM AUTHOR]

In this study, thermally reduced graphene oxide (TRG)-containing polyurethane nanocomposites were obtained by the extrusion method. The content of TRG incorporated into polyurethane elastomer systems equaled 0.5, 1.0, 2.0 and 3.0 wt%. The morphology, static and dynamic mechanical properties, and thermal stability of the modified materials were investigated. The application of TRG resulted in a visible increase in material stiffness as confirmed by the measurements of complex compression modulus (E′) and glass transition temperature (Tg). The Tg increased with increasing content of nanofiller in the thermoplastic system. The addition of thermally reduced graphene oxide had a slight effect on thermal stability of the obtained materials. The incorporation of 0.5, 1.0, 2.0 and 3.0 wt% of TRG into a system resulted in increased char residues compared to unmodified PU elastomer. Also, this study demonstrated that after exceeding a specific amount of TRG, the physicomechanical properties of modified materials start to deteriorate. [ABSTRACT FROM AUTHOR]

• Review of carbon nanomaterial composite phase change materials thermal properties. • 0D, 1D, 2D, and 3D carbon nanomaterials effects on thermal properties are explored. • Thermal conductivity, enthalpy, and latent heat capacity enhancements are compared. • Percolation, geometry, interfacial chemistry, and loading is considered. • Effects of functionalization and encapsulation of fillers are compared. Energy conservation is an ever-growing field of research, due to the global energy demands continuously escalating and the need of cleaner energy sources with a reduced carbon footprint. To preserve resources, latent heat thermal energy storage systems, utilizing phase change materials (PCMs) are being researched due to their high heat capacities and the lack of practical thermal conductivity. This review focuses on a numerical comparison of retained enthalpy and thermal conductivity enhancement (TCE) of PCMs with additions of multi-dimensionality carbon nanofillers, that are functionalized and encapsulated, whilst trying to account for the physical phenomena that influence the effects. Interfacial chemistry between the filler and PCM will affect filler dispersion, composite TCE, enthalpy and stability. The thermal percolation threshold has been explored for 0D, 1D, 2D and 3D fillers. Assessments for the best dimensionality filler at low weight fraction have also been made. The highest TCE at low weight fractions is seen from 3D carbon nanomaterials, and at high weight fraction from unfunctionalized 2D carbon nanomaterials. The data gathered from many research papers has allowed the confirmation of a thermal percolation threshold in 2D nano carbon filled PCMs. By studying the intermolecular interactions of the filler and PCM material, the composite properties can be maximised, such as achieving a high composite enthalpy via maximizing the degree of PCM crystallization. Therefore, this review will have use for researchers to plan new experiments and head in a forward direction towards innovation. However, there is a need for more research in this field on the topics of 1D and 2D nanocarbon fillers at high wt%, in order to compare their effectiveness and percolation with the other dimensionality fillers. There is, also, a need for more concise and complete reporting of data by researchers in the field due to the complex interconnected influences of the different material properties; doing so will make reviewing and comparison more accurate and faster, allowing more conclusions to be drawn from further review by future researchers. [ABSTRACT FROM AUTHOR]

HDPE-based composite fibers filled by original and annealed carbon nanodiscs (oND and aND, respectively) were prepared by melt extrusion technology with high-temperature orientational drawing up to draw ratio DR = 8. The thermal properties of the obtained fibers were investigated by DSC and TGA methods. It was shown that the nanofillers can be influenced by high temperatures, at which the molecular mobility in the interlamellar regions became active, while the melting point and the crystallinity degree of the samples were not affected. Short- and long-term mechanical properties of the nanocomposite fibers were studied as well. Very rare mechanical testing of the knotted fibers was carried out and, as a result, a decrease of the knot strength up to 35% was detected. It was also revealed that the carbon nanodiscs do not reinforce the composite fibers and play a negative role in the creep processes, while the Young's modulus can be improved by 2 times for the oriented samples. [ABSTRACT FROM AUTHOR]

Thermal properties of volcanic ash filled polyphenylene sulfide (PPS) composites have been investigated with respect to surface treatment that was conducted with 3-aminopropyltriethoxysilane (3-APTS) which had an organic functional group. Volcanic ash/PPS composite samples were prepared by using DSM Xplore 15 ml twin screw microcompounder and DSM Xplore 12 ml injection molding machines. The content of volcanic ash in composite samples was varied as 10 and 15 wt%. Volcanic ash filler dispersion and adhesion between volcanic ash particles and PPS matrix were examined by scanning electron microscopy. Thermal properties such as crystallization and melting behavior were investigated by TA Instruments Q200 differential scanning calorimeter. According to the test results, the relation between the thermal properties and surface treatment was determined as a function of melting temperature and melting enthalpy. Additionally, crystallization behavior was investigated according to surface treatment. [ABSTRACT FROM AUTHOR]

Paddy Straw Powder (PSP) show potential as a new reinforcement based-natural fibre. A Haake internal mixer was used to incorporated paddy straw powder (PSP) into polylactic acid (PLA). Polylactic acid (PLA)/paddy straw powder biocomposite was prepared using constant rotor speed (60 rpm) for 14 minutes at 180∘C. The effects of paddy straw powder content (5-20 wt %) on mechanical and thermal properties of the biocomposites were investigated. The tensile strength of the biocomposites was above 30 MPa up to 15 wt.% of PSP whereas the elongation at break was ranged between 2-3% with the incorporation of PSP up to 15 wt.%. Modulus elasticity was increased by increasing the paddy straw powder content. Differential scanning calorimetry (DSC) results have demonstrated a minor effect of the rice straw on thermal behavior of PLA resin Thermogravimetry, analysis (TGA) demonstrated that thermal stability of PLA/PSP biocomposites is reduced by the incorporation of PSP. [ABSTRACT FROM AUTHOR]

Abstract: Carbon materials, such as graphite oxides, carbon nanotubes and graphenes, have exceptional thermal conductivity, which render them excellent candidates as fillers in advanced thermal interface materials for high density electronics. In this paper, these carbon materials were functionalized with 4,4′-diaminodiphenyl sulphone (DDS), to enhance the bonding between the carbon materials and the resin matrix. Their visibly different properties were investigated. It seems that DDS-functionalization can obviously improve the interfacial heat transfer between the carbon materials and the epoxy matrix. The thermal conductivity enhancement of D-Graphene composites (0.493W/mK) was about 30% higher than that of D-MWNTs composites (0.387W/mK) at 0.5vol.% loading. The different effects among EGO, D-EGO, MWNTs, D-MWNTs and D-Graphene in polymer composites were also discussed. It was demonstrated that DDS-functionalized carbon materials had an obvious effect on the thermal performances of composite materials and were more effective in thermal conductivity enhancement. [Copyright &y& Elsevier]

In this paper, in order to improve the electrical and thermal properties of SiC/EP composites, the methods of compounding different crystalline SiC and micro-nano SiC particles are used to optimize them. Under different compound ratios, the thermal conductivity and breakdown voltage parameters of the composite material were investigated. It was found that for the SiC/EP composite materials of different crystal types of SiC, when the ratio of α and β silicon carbide is 1:1, the electrical performance of the composite material is the best, and the breakdown strength can be increased by more than 10% compared with the composite material filled with single crystal particles. For micro-nano compound SiC/EP composites, different total filling amounts of SiC correspond to different optimal ratios of micro/nano particles. At the optimal ratio, the introduction of nanoparticles can increase the breakdown strength of the composite material by more than 10%. Compared with the compound of different crystalline SiC, the advantage is that the introduction of a small amount of nanoparticles can play a strong role in enhancing the break-down field strength. For the filled composite materials, the thermal conductivity mainly depends on whether an effective heat conduction channel can be constructed. Through experiments and finite element simulation calculations, it is found that the filler shape and particle size have a greater impact on the thermal conductivity of the composite material, when the filler shape is rounder, the composite material can more effectively construct the heat conduction channel. [ABSTRACT FROM AUTHOR]

The combination of a filler with a polymer results in a new material with changed properties. Some of these changes are advantageous while others are less favorable. Polymeric dispersions of nanometer-sized metal particles offer the possibility of functionalizing the polymer by properties coming from the large number of surface atoms and the quantum-size effects. Nanosized metals show properties that differ significantly from that of bulk metals, which makes these nano-composite systems intriguing for scientific study and potentially useful for a number of technological applications. This study is about changing the epoxy properties using appropriate fillers. [ABSTRACT FROM AUTHOR]

The results of studies of mechanical and thermal properties of synthesized elastomeric nanocomposites have been presented. An elastomeric multiblock terpoly(ester-b-ether-b-amide)s as polymeric matrix and nanoparticles SiO2 i TiO2 used as fillers. It was shown that the introduction of multiblock thermoplastic elastomer matrix of SiO2 and TiO2 nanoparticles allows to obtain nanocomposite materials with improved mechanical properties compared to the terpolymer before modification. An increase in glass transition temperature, which has a positive effect for the processing of terpolymers. [ABSTRACT FROM AUTHOR]

The leading purpose of this work was to broaden the current knowledge about the impacts of various chain configurations of polypropylene (PP), i.e., linear and branched form, on the thermal properties (thermal stability, thermal conductivity, crystallinity, thermal mechanical properties) of PP nanocomposites reinforced by graphene nanoplatelet (GnP) particles. The utilization of GnP with different particle size gave us good information about the impacts of filler's dimension on the thermal properties as well. Regardless of the PP type, EC1500-filled (small size GnP) composites showed higher storage modulus in the dynamic mechanical analysis. With respect to DSC results, incorporation of GnP, particularly GnP with smaller particles, led to a striking increment in crystallization temperature and crystallinity, and nucleating efficiency of GnP in linear PP-based composites was higher. The employment of GnP brought about an improvement in degradation temperature and thermal stability of nanocomposites, and smaller GnP was more effective in this context. However, due to its higher aspect ratio, EC100 GnP (large size GnP) could enhance thermal conductivity more satisfactory, specifically in linear PP-based samples. Unlabelled Image • Polypropylene(PP)/graphene nanoplatelet (GnP) nanocomposites were prepared via solid state mixing followed by melt blending. • Small GnP had better performance in dynamic modulus, while large GnP was more effective in thermal conductivity enhancement. • Long side chains in branched PP affected the formation of GnP network and thermal properties, adversely. [ABSTRACT FROM AUTHOR]

Hollow microspheres are widely used in syntactic foam as a lightweight filling material. Hollow glass microspheres (HGM) and hollow phenolic microspheres (HPM) were added to the phenolic resin to prepare phenolic syntactic foams. Then the mechanical properties, thermal insulation properties, and thermal property stability of them were studied. The mechanical test result shows that the flexural strength of phenolic syntactic foam gradually decreases with the increasing volume fraction of microspheres at room temperature. When the volume fraction of HGM is 20%, the specific strength of phenolic syntactic foam can rise to 0.0334 Nm/kg. HGM reduces the density of the phenolic syntactic foam and remains at high strength. In addition, the thermal conductivity of phenolic syntactic foam decreases with the increasing volume fraction of the hollow microspheres, indicating that the microspheres can effectively improve the thermal insulation performance of the phenolic syntactic foam. Meanwhile, the thermal conductivity of phenolic syntactic foam also increases as the heat treatment temperature rises. In addition, the thermal insulation performance of phenolic syntactic foam containing HGM is better than that containing HPM. Thermal analysis experiments show that the thermal weight loss rate becomes slower as the content of HGM increases. Therefore, HGM improves the thermal stability of the containing phenolic syntactic foam. However, the HPM reduces the thermal decomposition temperature and the thermal stability of the phenolic syntactic foam. This work provides the technical basis for applying phenolic syntactic foam as a heat insulation material. [ABSTRACT FROM AUTHOR]

In the study walnut shells (WS) and silanized walnut shells (S_WS) were used as cellulosic fillers for novel polyurethane (PU) composite foams. The impact of 1, 2 and 5 wt % of WS and S_WS on the foaming parameters, mechanical and thermo-mechanical properties of obtained materials were evaluated. The results have shown that compared to untreated WS filler, the application of S_WS leads to PU foams with more regular structure and improved physico-mechanical behavior of PU materials. For example, compared to controlled WS_0 foam, PU foams enhanced with 1 wt% of the S_WS exhibited better mechanical properties, such as higher compressive strength (~15% of improvement), better impact strength (~6% of improvement), and improved tensile strength (~9% of improvement). The addition of S_WS improved the thermomechanical stability of PU foams. This work provides a better understanding of a relationship between the surface modification of the walnut shell filler and the mechanical, insulating and thermal properties of the PU composites. Due to these positive and beneficial effects, it can be stated that the use of WS and S_WS as natural fillers in PU composite foams can promote a new application path in converting agricultural waste into useful resources for creating a new class of green materials. Image 1 • Walnut shells (WS) and silanized walnut shells (S_WS) have influence on foaming process of PU system. • Morphology of PU foams is significantly affected by the fillers content. • PU foams modified with S_WS are characterized by better mechanical and thermal properties. • The use of WS and S_WS as natural fillers in PU composite foams can promote a new application path. [ABSTRACT FROM AUTHOR]

Epoxy resin based thermal interfacial materials (TIMs) with high thermal conductivity have been obtained by filling Ag nanoparticle-decorated graphene nanosheets (GNSs) as thermal conductive fillers. The thermal conductivity ( k ) enhancement of epoxy resin based TIMs increases with the thermal filler loading. The more decoration of Ag nanoparticles on the GNS surfaces, the higher thermal conductivity enhancement of epoxy resin based TIM is. It is proposed that the bigger Ag nanoparticles acting as “spacers” increase the distance between the graphene sheets more than the smaller ones. It is not easy for graphene sheets to form stacked graphitic structures and the high specific surface area as well as other unique properties exhibited by 2D graphene are retained. Furthermore, the larger particle size is desired to minimize the scattering of phonons because of low interfacial thermal barrier. The obvious enhancement of thermal properties should be also attributed to the high intrinsic k of graphene and the effective thermal conductive networks forming by graphene and Ag nanoparticles. The synergistic effects including the stronger phonon Umklapp scattering, better phonon transmission trough the interfaces, decreasing Kapitza resistance, and decreasing ability of heat transfer by electrons result in the slight variation of k with the temperature. The weak temperature dependence of k is beneficial for TIM applications and can be obtained by controlling the addition of hybrid thermal fillers and quantity of decorated silver nanoparticles. [ABSTRACT FROM AUTHOR]

The effects of the filler size and content on thermal properties and thermal stability of polypropylene (PP) composites filled with four different sizes of multi-walled carbon nanotubes (MWCNTs) were investigated through thermogravimetric analysis. The results showed that the values of the decomposition temperature increased with increasing weight fraction and length–diameter ratio of the filler, while increased with decreasing filler diameter. The values of the residues increased approximately linearly with increasing filler weight fraction. The values of maximum mass loss rate decreased roughly with increasing filler weight fraction, while the influence of the filler diameter and length–diameter ratio on the maximum mass loss rate was insignificant. The thermal stability improvement might be attributed to the barrier function of the MWCNTs. This study provides a basis for further development of MWCNTs reinforced polymer composites with desirable thermal properties for potential application as energy materials. [ABSTRACT FROM AUTHOR]

Various glass-ceramics are widely used or considered for use as components of microelectronic materials due to their promising properties. In this study, borosilicate glass was prepared using the powder metallurgical route and then mixed with different amounts of Al2O3 and ZrO2 filler materials. Glass-ceramics are produced by high-energy ball milling and conventional sintering process under Ar or air. In this study, the effects of different filler materials and different atmospheres on the microstructural, thermal and dielectric properties were investigated. The data showed that ZrO2 filler material led to better results than Al2O3 under identical working conditions and similar composite structures. ZrO2 filler material significantly enhanced the densification process of glass-ceramics (100% relative density) and led to a thermal conductivity of 2.904 W/K.m, a dielectric constant of 3.97 (at 5 MHz) and a dielectric loss of 0.0340 (at 5 MHz) for the glass with 30 wt.% ZrO2 sample. This paper suggests that prepared borosilicate glass-ceramics have strong sinterability, high thermal conductivity, and low dielectric constants, making them promising candidates for microelectronic devices. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effect of white mud (WM) on mechanical and thermal properties of bamboo plastic composites (BPCs). Bamboo residue fibers (BRFs) and WM were added as the reinforcement, and high-density polyethylene (HDPE) served as the matrix. The lubricating agent and coupling agent were polyethylene wax and maleated polyethylene (MAPE), respectively. The mixture was used to manufacture BPCs using a twin-screw extruder. The crystal structure and thermal properties of BPCs were investigated by X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results showed that the particle size of the WM was 700 nm to 50 µm, which are made mainly of calcium carbonate. BPCs with WM significantly increased the flexural and tensile properties, but the impact strength decreased because of the presence of WM. The flexural and tensile strength of composites with 18 wt% BPF were increased by 36.81% and 6.26%, respectively, while the flexural and tensile modulus were increased by 164.29% and 64.33%, respectively. XRD demonstrated the WM had little effect on the crystal structure of BPCs. Compared to BPCs without WM, the T5% of composites with 22 wt% WM decreased by 27.9 °C. As the WM content increased, the crystallinity of the BPCs decreased initially, then increased with increasing WM content. [ABSTRACT FROM AUTHOR]

Superconducting test coils impregnated with epoxy composites containing cubic boron nitride (cBN) particles, hexagonal boron nitride (hBN) particles, and a mixture of cBN/hBN particles were fabricated, and their thermal and electrical properties were investigated using cool-down, over-current, and repetitive-cooling tests. Micro-voids, which may act as major obstacles to the formation of thermally conductive passages, were observed in the epoxy composites containing the cBN or hBN particle fillers alone but were absent in that containing the cBN/hBN particle mixture. The coil impregnated with epoxy containing the cBN/hBN particle mixture also exhibited superior cooling performance and thermal/electrical stabilities, indicating that this composite effectively facilitated heat transfer between the coil and liquid nitrogen. Moreover, the addition of the cBN/hBN filler reduced the difference in thermal contraction between the superconducting tape and epoxy composite. Overall, the use of the epoxy composite containing the cBN/hBN filler shows potential for the development of highly stable superconducting coils with considerably enhanced thermal conductivity and low coefficients of thermal expansion. [ABSTRACT FROM AUTHOR]

Electromagnetic interference shield materials which are multicomponent polymer nanocomposites consisting of insulating polymer matrix of poly (vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), organic/inorganic salts, electron-conducting nanofillers (MWCNTs), and insulating superparamagnetic nanoparticles (FeO), have been studied. It has been found that the introduction of the salts and nanofillers in PVdF-HFP not only improves the conducting nature and skin depth of the polymer nanocomposites but also keeps the composite films thermally stable up to ~ 200 °C. Changes in the surface morphology on addition of each individual constituent have been evidenced by scanning electron microscopy. The rheological study shows the plasticization effect of organic/inorganic salts as well as provides a good estimation of the polymer-particle interaction in the polymer nanocomposites. Furthermore, effect of organic/inorganic salts and interaction between the polymer and the fillers (MWCNTs and FeO) has also been observed in differential scanning calorimetry in terms of lowering of glass transition temperature (leading to enhanced flexibility). The stress versus strain behavior has shown specific interactions among different constituents of the shield material. [ABSTRACT FROM AUTHOR]

Graphene nanosheets have attracted considerable attention as ideal reinforcing filler materials for polymer composites due to their superior physical properties. In this paper, to investigate the influence of functionalized graphene on the electrical, mechanical, and thermal properties of solderable isotropic conductive adhesives (SICAs) with low-melting-point alloy, three types of SICAs [without and with graphene oxide (GO) and amine-modified GO (GO-NH)] were prepared. All SICA assemblies without and with different functionalized graphene sheets showed excellent electrical and mechanical properties due to the formation of uniform and stable metallurgical conduction paths. The epoxy composite with GO sheets showed superior thermal conductivity to the epoxy composite with GO-NH sheets. Our results demonstrated that graphene sheets within SICAs do not affect the electrical and mechanical properties of SICA joints, and that GO sheets are more suitable for enhancing the thermal conductivities of polymer composites than GO-NH sheets. [ABSTRACT FROM AUTHOR]

Recently, it is common application to use particle materials as fillers to improve engineering properties and lower the cost of finished product. Pumice powder is cheaper than most of traditional particle fillers, however use of pumice powders as a reinforcing material in composites has not been studied in literature. Hence, in this study we have investigated the mechanical and the thermal properties of pumice powder filled polyphenylenesulphide (PPS) composites. PPS composites were reinforced with pumice powder at different loading rates (0, 1, 3.5, and 10 wt%) and they were manufactured by twin screw extruder and injection molding machine. Thermal properties were investigated by thermogravimetric analysis and differential scanning calorimeter methods. Moreover, mechanical properties such as barcol hardness, tensile strength, and modulus of samples were investigated. Thermal properties of composite samples have varied significantly depending on the loading rate. Also mechanical properties of pumice powder filled PPS composites have showed better results than pure PPS. According to test results both of mechanical and thermal properties of composites have improved with pumice powder reinforcement and it is determined that pumice powders can be used instead of traditional particle fillers. [ABSTRACT FROM AUTHOR]

Thermal conductivity is a key property in many applications from electronic to informatics. The interaction of fillers with Sylgard 184 was studied; this study explores new composites and the influence of metal particles (copper and nickel), carbon-based materials (carbon nanotubes and carbon black), and ceramic nanoparticles (boron nitride) as fillers to enhance thermal properties of silicon-based composites. The effect of the fillers on the final performances of the composite materials was evaluated. The influence of filler volume, dimension, morphology, and chemical nature is studied. Specifically, FT-IR analysis was used to evaluate curing of the polymer matrix. DSC was used to confirm the data and to further characterize the composites. Thermo-mechanical properties were studied by DMTA. The filler morphology was analyzed by SEM. Finally, thermal conductivity was studied and compared, enlightening the correlation with the features of the fillers. The results demonstrate a remarkable dependence among the type, size, and shape of the filler, and thermal properties of the composite materials. Underlining a that the volume filler influenced the thermal conductivity obtaining the best results with the highest added volume filler and higher positive impact on the k of the composites is reached with large particles and with irregular shapes. In contrast, the increase of filler amount affects the rigidity of the silicon-matrix, increasing the rigidity of the silicon-based composites. [ABSTRACT FROM AUTHOR]

Very often, colored polyurethane (PU) foams are used in the industry, but until now the influence of the dye on the properties of PU foams has not been evaluated. Because of this, PU foam composites were prepared by the addition of red color pigment (Acid Red 74). This pigment was chosen due to its strong color that can enhance the aesthetic value of the foam. Additionally, the research allowed to determine how the pigment influenced the mechanical and functional properties of the PU foams. In this study, PU foams were prepared with the addition of commercial pigment with different weight ratios (0.1, 0.5 and 2 wt%) as a particulate modifier of PU foams composites. The features of resulting composite foams were evaluated by morphological (Scanning Electron Microscopy, SEM), thermal (Thermogravimetric Analysis, TGA), mechanical (compressive test, three-point bending test, Charpy impact test) and physical properties (apparent density, dimensional stability, contact angle, water uptake, color characteristics). Color analysis reveals that the addition of color pigment in PU foams has greatly improved the color of the PU foams to red. Moreover, it has been found that compared to the reference foam, composition with 0.1 wt% of the filler showed greater compressive strength (increase of 12%, from 0.25 to 0.28 MPa), better flexural strength (increase of 11%, from 0.41 to 0.46 MPa), less water uptake (decrease by 43%, from 9.8 to 6.5% after 24 h) as well as lower thermal conductivity (0.027 Wm−1K−1). • Pigment filler has an influence on foaming process of PU system. • PU foams containing 0.1 and 0.5 wt% of pigment filler are characterized by better mechanical and thermal properties. • Introduction of pigment filler over a certain optimal level (2 wt%) leads to deterioration of physico-mechanical properties of PU foams. [ABSTRACT FROM AUTHOR]

Abstract In the current study, it is found that the electrical properties of a co-continuous polystyrene (PS)/poly(methyl methacrylate) (PMMA) blend containing with conductive multi-wall carbon nanotubes (MWCNTs) can be remarkably improved via the thermal annealing treatment. Utilizing the on-line (rheometer and optical microscope) and off-line (transmission electron microscopy) instruments, the evolution of the morphology and microstructure of PS/PMMA/MWCNTs composites are visualized. It is observed that thermal annealing can induce the coalescence of small phases into the more perfect co-continuous phase structure, which can significantly improve the electrical properties of the composites. Moreover, the re-aggregation of MWCNTs under thermal annealing also helps to improve the electrical properties of the composites. Furthermore, it is worth to note that parts of MWCNTs can be enriched at the interface of a co-continuous PS/PMMA blend to build up the conductive network during the thermal annealing, which further enhances the electrical properties of the composites. [ABSTRACT FROM AUTHOR]

This study focuses on the mechanical, thermal properties, fracture morphology, and DC conductivity of graphite-reinforced polypropylene (PGP) composites for electromagnetic interference (EMI) shielding applications. Polypropylene (PP) and graphite powder (GP) are used as a matrix and filler materials to prepare PGP composites using a melt compounding technique. The results of thermal studies show that GP increases the thermal stability of PGP composites with an increase in filler amount. The tensile strength of the PGP composites was improved with the increase in GP content. The fracture morphology of the composites shows the clearance of polymer flow and good adhesion compatibility between PP and GP. Direct-current conductivity measurements indicate that PGP composites show an improvement in electrical conductivity. The EMI shielding effectiveness for PGP composites is −10.30 dB at 20 wt.% GP load in a bandwidth of X-band (8.2 GHz–12.4 GHz). [ABSTRACT FROM AUTHOR]

The article discusses the synthesis of exfoliated polypropylene and layered double hydroxide nanocomposites through melt-intercalation. The commercial significance of polypropylene has been driving a vivid investigation of polypropylene layered inorganic filler nanocomposites. These nanocomposites strengthened through layered inorganic fillers were induced with several unique properties such as changed mechanical properties, thermal stability, flame retardance and gas barrier properties.

CaCO3/PEEK (poly-ether ether ketone) composites were prepared on a twin-screw extruder with different mass ratio of CaCO3/PEEK from 0% to 30%. Four types of particles were used as filler in PEEK matrix. The influence of surface treatment with sulfonated PEEK (SPEEK) of the particles on the mechanical and thermal properties of the composites was studied. The experiments included tensile tests, flexural tests, notched Izod impact tests, TGA, DSC and SEM. The modulus and yield stress of the composites increased with CaCO3 particles loadings. This increase was attributed to the bonding between the particles and the PEEK matrix, as can be proved by the SEM pictures of tensile fracture surface of the composites. The impact strength of the composites was modified by the SPEEK coated on the CaCO3 particle surface. DSC experiments showed that the particle content and surface properties influenced the glass transition temperature (Tg) and melting temperature (Tm) of the composites. The Tg increased with the content of fillers while Tm decreased. In this study the fillers treated were found to give better combination properties, which indicated that SPEEK played a constructive role in the CaCO3/PEEK composites. [Copyright &y& Elsevier]

To obtain lightweight wood building materials with good thermal insulation, energy-saving properties, and satisfying mechanical properties, low-density fiberboard and hollow wood composites (HWC) embedded polyvinyl chloride tubes were fabricated by hot-pressing. Polyethylene glycol was used as the phase-change material to fill polyvinyl chloride tubes and obtain phase-change hollow wood composite (PHWC). The physical and mechanical properties of HWC and PHWC were tested, and their thermal properties were analyzed and simulated. The results showed that the thermal conductivities of low-density fiberboard, HWC, and PHWC ranged from 0.06 to 0.07 W/(m·K), indicating they had sufficient physical and mechanical properties to be used as thermal insulation building materials. The combination of series and parallel models accurately predicted the thermal conductivity of HWC and PHWC, whose structures were similar to a series structure. The addition of polyethylene glycol into HWC allowed the PHWC to store latent heat and reduce indoor temperature fluctuations. Heat transfer simulations showed that when used as a non-structural building wall material, the PHWC wall had a better energy efficiency compared with a concrete wall. Thus, PHWC has potential applications as thermal insulation and phase-change building material. Image 1 • Lightweight hollow wood composites with a density of 0.3 g/cm3 were fabricated. • The thermal conductivity of lightweight hollow wood composites is 0.06–0.07 W/(m·K). • Polyethylene glycol as a phase change material was added into hollow wood composites. • Phase-change lightweight wood composites were better insulators than concrete. [ABSTRACT FROM AUTHOR]

Abstract: Hybrid filler systems of multiwalled carbon nanotubes (MWCNTs) and carbon black (CB) were incorporated into two types of polyamide 12 (PA12) using small-scale melt mixing in order to identify potential synergistic effects on the interaction of these two electrical conductive fillers. Although no synergistic effects were observed regarding the electrical percolation threshold, at loadings well above the percolation threshold higher volume conductivities were obtained for samples containing both, MWCNT and CB, as compared to single fillers. This effect was more pronounced when using a higher viscous PA12 matrix. The formation of a co-supporting network can be assumed. The combined use of CB and MWCNTs improved the macrodispersion of MWCNT agglomerates, which can be assigned as a synergistic effect. DSC measurements indicated an effect of the nanofiller on crystallisation temperatures of PA12; however this was independent of the kind or amount of the carbon nanofiller. [Copyright &y& Elsevier]

Abstract: Nanostructured wollastonite was synthesized by a sol–gel method and then used as a filler for polypropylene (PP). The obtained wollastonite particles were investigated using XRD, TEM and FTIR techniques. Non-isothermal crystallization measurements revealed that the wollastonite filler reduced the crystallization temperature of the matrix. TGA analyses showed improved thermal stability of the nanocomposite with respect to that of the pure polypropylene. From the DMA tan δ curves, it was concluded that the introduction of the filler into the PP matrix induced a slight shift of the β-transition (glass transition) towards higher temperature. The measurements of storage moduli showed that the nanocomposites have higher stiffness than the pure PP over the whole range of test temperature. An increase in stiffness was also confirmed by tensile measurements. [Copyright &y& Elsevier]

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Influence of CdS-filler particles in the micrometer size range on the properties of the polystyrene (PS) matrix was studied using structural and thermal techniques. Improvement of the thermal stability of the PS matrix for about 50 K was found in the presence of the CdS-filler. Infrared measurements revealed that interaction between the surface of CdS-filler particles and the PS chain is weak. Non-significant changes in the glass transition temperature of the PS matrix upon the incorporation of CdS-filler particles also suggest weak interaction between filler and polymer. [Copyright &y& Elsevier]

This work sought to assess the suitability of using boards produced with plaster of Paris (P.O.P) and various weight proportions of groundnut seed coat (GSC) as well as P.O.P and similar proportions of waste newspaper paste (WNP) as ceiling in building design. The results obtained from the investigation of thermal and mechanical properties of the fabricated boards revealed that with the use of GSC as filler, the samples were of higher mean values of specific heat capacity, thermal conductivity, thermal absorptivity, but lower mean values of bulk density, thermal diffusivity, percentage water absorption, flaking concentration and flexural strength when compared to the samples with similar proportions of WNP as filler content. Also, the sample with 13.8% content of GSC and the one containing 22.5% of WNP were found to exhibit an impressive performance. Generally, it was observed that the samples filled with either GSC or WNP were lighter than pure P.O.P samples and the recorded values for all the measured properties favoured them for use as ceiling material in buildings. It is noteworthy that the proportion of the filler can be adjusted for optimum performance of such environmentally-friendly and cost-effective ceilings. Utilizing groundnut seed coat and waste newspapers as filler materials in fabrication of P.O.P ceiling can help to reduce environment pollution level, ensure better thermal insulation of buildings and solve the lingering problem of high cost of using P.O.P or other conventional materials as ceiling in buildings by the end-users. [ABSTRACT FROM AUTHOR]

The present work investigates the ablative and thermal properties of phenol formaldehyde glass-fabrics laminates filled with mixtures of corundum Al2O3 and carbon C powders. The laminates specimens of dimensions 10x25x35 mm were treated with hot combustion gases having a temperature of more than 2800°C. The carbonization of the thermosetting matrix was observed. Statistical methods for planning experiments were used, and the effect of components on the average rate of ablation, the maximum back side temperature of specimen and the average mass waste under intensive heat flow after 30 s of treatment with hot combustion gases was established. The best thermal protective properties were exhibited by the laminate containing 30% matrix, 25% fibre glass-fabric reinforcement, 9% corundum, and 36% carbon powder. [ABSTRACT FROM AUTHOR]

The study reports the results of investigation of basic processing and thermal properties of low-density polyethylene modified with two types of natural filler: wheat bran and pumpkin seed hulls, their content ranging from 5% to 15% relative to the matrix. In addition, physical properties of the produced granulates are determined, i.e. the relationship between their density and the applied contents of the tested fillers. Furthermore, the study reports the results concerning longitudinal shrinkage, abrasion resistance and cold water absorption of injection molded tensile specimens. [ABSTRACT FROM AUTHOR]

PBS/nano-CaCO 3 composites with various nano-CaCO 3 weight fractions were prepared by melt blending. The thermal behavior, dynamic mechanical properties and rheological properties of the composites were investigated. DSC measurements revealed that the nano-CaCO 3 particles had little influence on the crystallization and melting behavior of PBS. Thermogravimetric analysis showed that the introduction of nano-CaCO 3 tended to improve the thermal stability of PBS. Dynamic mechanical analysis showed that the G′ and G″ of the PBS/nano-CaCO 3 composites were improved significantly when the nano-CaCO 3 content was not more than 3wt%, while the G′ and G″ were mainly decided by the PBS matrix when the nano-CaCO 3 content exceeded 3wt%. Rheological results showed that G′ < G″ over the frequency range, illustrating the viscous behavior of the samples. The η* of all the samples remained almost constant when the frequency was not more than 0.25 rad/s, which showed the characteristic of a Newtonian fluid. A strong shear thinning effect was observed for all the samples when the frequency exceeded 0.25 rad/s. Furthermore, the microstructure and the relaxation mechanism of the PBS/nano-CaCO 3 composites mainly depended on the PBS matrix. [ABSTRACT FROM AUTHOR]

A mathematical correlation for evaluating the effective thermal conductivity ( k eff ) of hybrid polymer composites filled with two dissimilar particulate fillers is developed using the law of minimal thermal resistance and equal law of specific equivalent thermal conductivity. The estimations are validated with experimental results. Epoxy and polypropylene are chosen as matrix materials. Two conductive fillers, aluminium nitride (AlN) and aluminium oxide (Al 2 O 3 ) and two insulative fillers, pine wood dust (PWD) and rice husk (RH) are chosen as filler in present study. Sets of thermoset polymer composites (epoxy based) and thermoplastic composites (polypropylene based) are fabricated by hand lay-up technique and compression molding technique respectively. k eff of all the fabricated composites are measured by Unitherm™ Model 2022 tester as per ASTM E-1530. The measured values are than compared with the values obtained from the proposed mathematical model for 0–15 vol% filler concentration. While there is no theoretical model available in the literature so far for estimation of k eff for polymer composites with hybrid fillers, it is encouraging to notice that the measured values are in close approximation with the values predicted by the model proposed in this work. [ABSTRACT FROM AUTHOR]

Abstract: A two-dimensional numerical model is developed to simulate the transient operation of a thermosyphon with various working fluid filling ratios. Conservation equations for mass, momentum, and thermal energy are solved using finite volume scheme to determine the hydrodynamic and thermal behavior of the thermosyphon. The heat transfer due to the liquid pool and liquid film are accounted for. The numerical model is validated through comparison with experimental data available in the literature. The model is capable of predicting the optimal filling ratio which corresponds to a condensate film extending from the condenser end cap to the evaporator end cap at steady-state for a given heat input. Overfilled and underfilled conditions for which the working fluid inventories are respectively greater than and less than the optimal case are also investigated. Simulation results show that the evaporator temperature of the underfilled thermosyphon rises dramatically due to dryout. The optimally-filled thermosyphon has the shortest response time and the lowest thermal resistance, however, a slight increase in the input power will cause breakdown of the condensate film. The overfilled thermosyphon poses a slightly slower thermal response and greater thermal resistance compared to the optimal condition. To ensure optimal and stable steady-state operation, an optimally-filled thermosyphon is recommended with a small amount of additional working fluid to prevent breakdown of the liquid film. [Copyright &y& Elsevier]

This paper presents a study of the mechanical and thermal properties of kenaf fiber (KF) reinforced polypropylene (PP)/magnesium hydroxide (MH) composites. Pure PP samples show low tensile, flexural and flame retardant properties. It was found that KF and MH filler insertion improved the properties of PP composites. The incremental addition of KF fiber between 0 and 20 weight percent in composites results in higher tensile modulus and decomposed mass loss at onset temperature, but lower tensile strength, elongation, flexural strength and onset temperature. Addition of 25 wt% KF produces slightly higher flexural strength. Increasing the volume of MH filler in the composites caused lower strength, tensile modulus and elongation, but higher onset temperature and 2nd peak temperature in thermogravimetric analysis (TGA) testing. Increasing the KF content in the PP matrix resulted in lower mass residue. Increasing the KF content in composites containing MH increased the mass residue at the end of the testing. [ABSTRACT FROM AUTHOR]

Thermal and electrical conductivity of unsaturated polyester resin with copper filler composite material are investigated both theoretically and experimentally. In the experiments, polyester matrix is combined with dendrite-shape copper to determine the effects of both filler size and content on thermal and electrical conductivity, respectively. It is observed that the increase in the concentration causes the thermal and electrical conductivity of composite mixture to grow up. It has also been observed that the both thermal and electrical conductivity increase with increasing filler particle size. [ABSTRACT FROM AUTHOR]