Reduction In Coefficient Of Thermal Expansion Research Articles

Hybrid effect of graphite and carbon fibers on thermal properties of copper/graphite/carbon fibers composites

To maintain the high thermal conductivity (TC) and reduce the coefficient of thermal expansion (CTE) of conventional copper (Cu)/graphite composites, novel Cu/graphite/carbon fibers (CFs) hybrid composites were designed by replacing part of graphite with Cu-coated CFs and prepared by spark plasma sintering (SPS) process. The incorporation of CFs resulted in increased interface density, reduced twin boundaries, and significant grain refinement of the Cu matrix. TEM observations revealed that the Cu-coating on surfaces of CFs enhanced the interfacial bonding between CFs and Cu matrix. The Cu-coated CFs can act as connecting channels between graphite particles, which partially compensate the negative effect on TC. Furthermore, strong interfacial bonding and large Cu/CFs contact areas contribute to the reduction in CTE. As a result, the Cu/30%graphite/10%CFs composite showed TC and CTE of 453.5 Wm−1 K−1 and 10.9 × 10−6 K−1, respectively. Compared to the Cu/40%graphite composite, the CTE of Cu/30%graphite/10%CFs composite was reduced by ∼20 % with only 4.4 % sacrifice in TC. Consequently, the Cu/graphite/CFs hybrid composites showed an excellent balance between TC and CTE, which are superior to the conventional Cu/graphite and Cu/CFs composites. The findings of this work provide new insights for designing and preparing new thermal management materials.

The Synergy Reinforcement Effect of Sm0.85Zn0.15MnO3 and ZrMgMo3O12 on Sm0.85Zn0.15MnO3-ZrMgMo3O12/Al-20Si Composites.

Negative thermal expansion (NTE) ceramics Sm0.85Zn0.15MnO3 (SZMO) and ZrMgMo3O12 (ZMMO) were selected to prepare Sm0.85Zn0.15MnO3-ZrMgMo3O12/Al-20Si (SZMO-ZMMO/Al-20Si) composites using ball milling and vacuum heating-press sintering processes in this study. The synergistic effect of the SZMO and ZMMO NTE ceramic reinforcements on the microstructure, mechanical properties, and coefficient of thermal expansion (CTE) of the composites was investigated. The results show that the processes of ball milling and sintering did not induce the decomposition of SZMO or ZMMO NTE ceramic reinforcements, nor did they promote a reaction between the Al-20Si matrix and SZMO or ZMMO NTE ceramic reinforcements. However, the excessive addition of SZMO and ZMMO NTE ceramics led to their aggregation within the composite. Adding a small amount of SZMO in combination with ZMMO effectively increased hardness and yield strength while reducing CTE in the Al-20Si alloy. The improvement in strength was primarily provided by SZMO, while the inhibition effect on CTE was primarily provided by ZMMO. An evaluation parameter denoted as α was proposed to evaluate the synergy effects of SZMO and ZMMO NTE ceramic reinforcements on the mechanical properties and CTE of the composites. Based on this parameter, among all composites fabricated, adding 2.5 vol% SZMO NTE ceramic and 10 vol% ZMMO NTE ceramic resulted in an optimal balance between CTE and strength for these composites with a compressive yield strength of 349.72 MPa and a CTE of 12.55 × 10-6/K, representing a significant increase in yield strength by 79.20% compared to that of Al-20Si alloy along with a notable reduction in CTE by 26.44%.

Towards high performance durable ceramic fuel cells using a triple conducting perovskite cathode

To guarantee the efficient and durable operation of oxygen ion/proton-conducting ceramic fuel cells, the cathode materials need to be versatile in terms of high activity, good CO2 resistance, and matched thermal expansion behavior with electrolyte, etc. In this study, we substituted 10% Nb to the B-site of parent perovskite-BaCo0.7Fe0.2Y0.1O3-δ, to form a single-phase material with triple conducting (H+/O2-/e-) capability as a highly ORR-active cathode. The doped BaCo0.6Fe0.2Y0.1Nb0.1O3-δ (BCFYN) shows promising ORR activity due to the optimized oxygen vacancy, improved hydration capacity, and accelerated charge transfer kinetics. The reduction of thermal expansion coefficient (TEC) and enhanced CO2 resistance also facilitate the cathode durability. As a result, the area-specific resistances of BCFYN electrode at 550 °C for oxygen-ion and proton conducting symmetrical cells were only 0.106 and 0.24 Ω cm2, respectively. These results indicate that BCFYN is a highly promising cathode material for both SOFCs and PCFCs.

A structured approach to the determination of residual stresses in an epoxy-amine coating and the influence of thermal ageing on the thermomechanical properties, residual stresses and the corresponding failure modes of coating

The purpose of this research was to develop a structured approach for the calculation of residual stresses in organic coatings through the experimental determination of thermomechanical properties of the epoxy-amine coating. The feasibility of this proposed method was validated by the presence of cracks on epoxy amine coating subjected to isothermal ageing at 180 °C for a period of 8 weeks, followed by thermal shock by water quenching at 0 °C, when the tensile strength of coating (8.00 MPa) was surpassed by the accumulated residual stress in the coating (9.66 MPa). The influence of thermal ageing on the thermomechanical properties, residual stresses and the corresponding failure modes were also evident. Significant variation of thermomechanical properties such as the increase in Tg from 77.60 °C to 120.50 °C, reduction of thermal expansion coefficient from 51.74×10−6°C−1 to 40.27×10−6°C−1, reduction of elastic modulus from 1600 MPa to 1400 MPa, and reduction of ultimate tensile strength from 27.00 MPa to 8.00 MPa after thermal ageing were observed. These variations have ultimately led to the increase of residual stresses in coatings that has resulted in the formation of cracks.

Investigation of mechanical properties and thermal expansion coefficient of epoxy composites modified with MXene nanofluids

Epoxy resin (EP) is a highly promising material with great potential in packaging and adhesion. However, enhancing the toughness and reducing the coefficient of thermal expansion (CTE) of EP at a low filler content remains a challenge. To address this issue, we designed MXene nanofluids (MXene NFs) to modify epoxy resin. Remarkably, with a low filler content of 1 wt% MXene NFs, the compression, impact, and lap shear strength of the composites improved to 86.85 MPa, 68.87 kJ/m2, and 11.12 MPa, respectively. Additionally, the MXene NFs/EP displayed a 15.48% reduction in CTE as compared to pure EP. This study highlights the immense potential of MXene NFs as practical fillers for epoxy composites, expanding their diverse range of applications in various fields.

Buckling behavior of non‐uniformly heated 3D printed plain and functionally graded nanocomposites

AbstractThe functionalized multi‐walled carbon nanotubes (MWCNTs) (0.5–5 wt.%) are compounded with high density polyethylene (HDPE), and, subsequently, used for extruding nanocomposite filaments to fabricate nanocomposites (NCs) and functionally graded nanocomposites (FGNCs) through 3D printing. The 3D printed NCs are investigated for coefficient of thermal expansion (CTE), and buckling under different non‐uniform temperature distributions (case‐1: left edge heating, case‐2: centre heating, and case‐3: left and right edge heating). A significant reduction in CTE is observed with MWCNT addition and gradation. The highest reduction in CTE is observed for H5 (5 wt.% of MWCNT in HDPE) NC and H1 ⟶ H3 ⟶ H5 (FGNC‐2) among the NCs and the FGNCs. It is noted that Tcr (critical buckling temperature) is highest for case‐3 and lowest for case‐2. The highest deflection is noticed in case‐2, while no significant difference is observed in case‐1 and case‐3 heating conditions. It is also observed that Tcr increases with gradation and MWCNTs addition. The H5 NC and FGNC‐2 exhibited the highest Tcr among the NCs and FGNCs, respectively. The maximum deflection is noticed for HDPE, whereas the minimum deflection is noticed for FGNC‐2 and H‐5 NC among the tested samples. The results also revealed that Tcr is very sensitive to type of heating.

Properties of polyphenylene sulphide/glass fibre composites with negative thermal expansion ceramic fillers

The high coefficient of thermal expansion (CTE) of polymeric composites can cause large deformation under temperature changes, affecting coupling with devices made of other materials in radio frequency (RF) communication systems and limiting their application in RF systems. In order to obtain polyphenylene sulphide (PPS)-based composites with low CTE, a series of PPS-based composites containing different loadings of ceramic powders (including Zr2WP2O12, BN, AlN, Al2O3) were fabricated by melt extrusion method using PPS with 40 wt% glass fibre (GF) as matrix material. The experimental results showed that the PPS composites with Zr2WP2O12 (ZWP) as a filler had a lower CTE compared to the samples with other fillers at the same filler loading. The CTE of PPS/GF/ZWP steadily decreased with increasing ZWP addition. At 20 vol% ZWP loading, a 67% (about 18 ppm/°C) reduction of CTE compared to the PPS/GF was achieved. The addition of ZWP powder to PPS/GF also led to an improvement in the dielectric loss of the composite. When the ZWP content is 20 vol%, the dielectric loss of the composites is about 0.0035, which is 24.4% lower than PPS/GF. Hence, the PPS/GF/ZWP composites have great potential for applications in RF communication systems.

Performance improvement of free CaO containing magnesia with ZrSiO4 addition

Free CaO containing magnesia has limited application due to poor resistance to hydration, slag penetration and thermal shock. This work aimed to improve the performances of such magnesia by introducing microscale ZrSiO4 powder. The results showed that the relative density of the specimens reduced from 92.1 % to 90.9 % when adding 1 wt% ZrSiO4 due to formation of Ca2SiO4 and CaZrO3, but then gradually increased to 96.2 % with further increasing ZrSiO4 to 7 wt% owing to the enhanced mass transfer and MgO grains growth caused by generation of c-ZrO2 and CaMgSiO4. The addition of ZrSiO4 obviously improved hydration resistance of the specimens, whose weight gain rate after the hydration test reduced significantly from 0.38 % to 0.01 % as the ZrSiO4 increasing from 0 wt% to 7 wt%. Thermal shock resistance (TSR) of the specimens reduced slightly when adding 1 wt% ZrSiO4 owing to the presence of more irregular pores, but then improved dramatically with further increasing ZrSiO4 due to the reduction in thermal expansion coefficient and occurrence of crack deflection. Besides, slag penetration was accelerated in the specimen with 1 wt% ZrSiO4 due to its lowered densification, while further increasing ZrSiO4 effectively improved the slag penetration resistance, attributing to the increase in MgO grain size and density and formation of the CaZrO3 containing dense layer preventing further slag infiltration.

Sintering behavior and thermal shock resistance of aluminum titanate (Al2TiO5)-toughened MgO-based ceramics

In order to improve the thermal shock resistance of MgO-based ceramics, aluminum titanate (Al2TiO5)-toughened MgO-based ceramics were successfully prepared by solid state sintering at 1450 °C and 1550 °C for 3 h starting from MgO and as-synthesized Al2TiO5 powders. The effects of various contents of Al2TiO5 second phase on the sintering behavior and thermal shock resistance of MgO-based ceramics were investigated. The sintering behavior of sintered samples was evaluated by comparing the relative density, apparent porosity, bending strength, phase composition as well as microstructure. The thermal shock resistance of sintered samples was characterized by using the residual bending strength after three thermal cycles and thermal expansion coefficient. The obtained samples with 10 wt% Al2TiO5, which were sintered at 1550 °C for 3 h, showed the highest relative density, lowest apparent porosity as well as optimum bending strength. In addition, the samples added 15 wt% Al2TiO5 at 1550 °C with a dwell time of 3 h were the highest residual bending strength and lowest thermal expansion coefficient. It revealed that the enhancement in thermal shock resistance was ascribed to the reduction of thermal expansion coefficient.

Barium-calcium aluminosilicate glass/mica composite seals for intermediate solid oxide fuel cells

In this paper, the effects of phlogopite mica addition on the properties of barium-calcium-aluminosilicate (BCAS) glass seals are studied. Accordingly, BCAS glass powder is mixed with up to 30 wt% of phlogopite mica; the resulting mixture is formed and sintered at different temperatures. The microstructure and phase content of the samples are then analyzed by scanning electron microscope (SEM) and X-ray diffraction method. Mechanical properties including, hardness, compression strength, fracture toughness and Young's modulus are investigated. The coefficient of thermal expansion (CTE) and softening temperature of the seals are measured. The electrical conductivity of the selected specimens is studied by applying the electrochemical impedance spectroscopy method. The performance of the composite seals is analyzed under fuel cell working conditions by the leak test. It is found that the samples with the mica content of more than 10 wt% cannot be sintered to near full relative density. The sintering temperature above 750°C raises the risk of unfavorable reactions between mica and the BCAS glass matrix. It is also revealed that the addition of 5 wt% phlogopite increases Young's modulus and fracture toughness of the BCAS glass seals by 13% and ~633%, respectively, without impairing other mechanical and thermal properties. The composites seals with more than 10 wt% of mica content don't meet the required mechanical properties demands for SOFC seals. It is found that the composite seal with 5 wt% of phlogopite mica has very low electrical conductivity and leak rate of less than 1.2×10−4sccm/cm. This composite seal shows high thermal stability with ~5% reduction in CTE after 10 cycles under SOFC working conditions and consequently can be considered as a promising seal for SOFCs.

Modeling Concrete Thermal Expansion Based on the Packing Density Theory

In this study, the effects of supplementary cementitious materials with changes in the structure of the concrete pores have been examined on the coefficient of thermal expansion (CTE) at different ages. The results indicated a descending trend for the CTE of the reference concrete up to 60 days (diminishing by about 12%), after which it remained constant. In contrast, an opposite trend was observed for the slag-containing concrete, i.e., the descending trend started after 60 days, and its CTE declined by 10% up to 120 days. In the following, two equations are presented for the concrete to estimate the CTE of the concrete during its lifetime based on its CTE at the age of seven days. Across all the concretes, the reduction of CTE was associated with lowered porosity. Moreover, evaluating the distribution of the pore size showed that when the pore diameter decreased, the CTE decreased as well, indicating a strong relationship between the median diameter of the pores and the CTE. Considering the fact that the concrete’s CTE depends on aggregates and the cement paste, a model was presented based on the CTE of the cement paste and its packing density to estimate the CTE of the concrete.

One-pot synthesis of aminated cellulose nanofibers by “biological grinding” for enhanced thermal conductivity nanocomposites

Aminated cellulose nanofibers (A-CNF) with high thermostability (>350 ℃), high crystallinity (81.25 %), and high dispersion stability were extracted from “biological grinding” biomass through one-pot microwave-hydrothermal synthesis. Worm-eaten wood powder (WWP) as the product of “biological grinding” by borers is a desirable lignocellulose for fabricating A-CNF in a green and cost-effective way since it is a well-milled fine powder with dimension of dozens of microns, which can be used directly, saving energy and labor. Generated A-CNF proved to be an excellent reinforcing and curing agent for constructing high performance epoxy nanocomposites. The nanocomposites exhibited a thermal conductivity enhancement of about 120 %, coefficient of thermal expansion reduction of 78 %, and Young’s modulus increase of 108 % at a low A-CNF loading of 1 wt.%, demonstrating their remarkable reinforcing potential and effective stress transfer behavior. The process proposed herein might help to bridge a closed-loop carbon cycle in the whole production-utilization of biomass.

Microstructures and unique low thermal expansion of Invar 36 alloy fabricated by selective laser melting

Invar 36 alloy, which presented extremely low coefficient of thermal expansion (CTE), was fabricated by selective laser melting with island scanning strategy. The microstructures and CTE were systematically characterized. The as-SLMed Invar 36 is mainly composed of fcc γ phase and sparse bcc α precipitates, which are consistent with the phases of the wrought one. The grains grow along the maximum temperature gradient directions, as the microstructure on the side surface is dominated by large columnar grains. The cross-section shows a large number of small columnar grains in the melt pool. The low laser energy density results in the lack-of fusion pores and corresponding high level porosity up to 15%. When the laser energy density is 99.2 J/mm3 and 198.4 J/mm3, excellent quality is obtained, as the porosity is only within 0.2–0.4%. Due to the porosity and nickel element evaporation, the CTE is 1.72–1.96 × 10–6 °C−1 that is lower than that of wrought one. Besides, lower than 99.2 J/mm3, the decreasing laser energy density leads to the reduction of CTE, since the pores provide extra space for internal thermal expansion. Higher than 99.2 J/mm3, the metal vaporization rate and vapor pressure are enhanced with the increasing laser energy density, and then the loss of nickel element leads to the reduction of CTE.

Effect of Carbon Nanotube (CNT) Content on the Hardness, Wear Resistance and Thermal Expansion of In-Situ Reduced Graphene Oxide (rGO)-Reinforced Aluminum Matrix Composites

Aluminum matrix composites reinforced with reduced graphene oxide (rGO) and hybrid of carbon nanotube (CNT) and rGO are fabricated by solution coating powder metallurgy process. The hardness, wear resistance and coefficient of thermal expansion (CTE) of the reinforced aluminum composites and the associated microstructural changes with rGO range (0.2–0.6 wt%) and hybrids of 0.2 wt% CNT–rGO at different ratios have been investigated. The intensive microstructural observations show that rGO is adsorbed on Al particles and uniformly distributed in the Al matrix composites. The hardness values of the composites increase significantly with rGO reinforcement exhibiting the maximum hardness at 0.4 wt% rGO. Compared with the hybrid composites CNT–rGO/Al counterparts fabricated by the same route and wt. percent of 0.2, the hardness values in the hybrid CNT–rGO increase considerably. Similar to the hardness, the results of wear tests also exhibit corresponding variation in the values of the wear rates. The improvement in the wear resistance of the hybrid CNT–rGO /Al composite is pronounced in this work. Whereas the rGO reinforcements decrease significantly the wear rate of the aluminum-base by 98%, the wear resistance of the corresponding hybrid CNT–rGO is significantly higher than that of the preceding composites. Maximum CTE reduction of 28% was recorded for hybrid CNT–rGO (1:1) reinforced composite.

Microstructures and properties of Ag–Cu–Ti–In composite fillers for electronic packaging applications

With excellent thermal cycling performance, active metal brazing (AMB) ceramic substrates have been highly competitive materials for high power packaging. In related researches, composite filler is an effective way to improve the comprehensive performance of ceramic substrates. The effects of particle hardness on microstructure and properties (i.e., coefficient of thermal expansion (CTE), elastic modulus and compression properties) of Ag–Cu–Ti–In composite fillers were studied in this paper. The results showed that the microstructures of composite fillers were refined with the increase of graphite and TiC content. Meanwhile, the reduction of CTE of composite fillers added with TiC particles is better than that of graphite particles. The CTE of G10 sample is 7.4% lower than that of the sample without particle, and T10 sample is 8.9% lower. Furthermore, TiC particles increased both elastic modulus and yield strength of the composite fillers while graphite particles mainly had an opposite effect. The bulk modulus of the composite fillers drops sharply from 95.96 to 12.64 GPa when the content of graphite particles was 10 wt% compared with that of the filler metal without particles. The yield strength of composite filler with graphite content of 1 wt% reaches 380 MPa, which is caused by the in situ reaction between graphite and Ti. However, the elastic modulus and the yield strength of the composite fillers increases with the increase of TiC content.

Epoxy nanocomposites with reduced coefficient of thermal expansion

ABSTRACTControl of the coefficient of thermal expansion (CTE) of polymeric materials is critical in many applications, particularly the electronics industry where CTE mismatches have caused failures. In theory, adding exfoliated nanoplatelets with high aspect ratios would offer an effective solution for reducing CTE, but reported results have not been compelling due to poor dispersion. In this study, α‐zirconium phosphate (ZrP) nanoplatelets, along with organic surfactants, were added to epoxy thermosets. The CTE reduction and glass‐transition temperature (Tg) were measured while the molecular weight of the surfactant was varied. High‐molecular‐weight surfactants are effective for ZrP exfoliation and dispersion, but they can also lead to a reduction in Tg and hinder the drop in CTE. A combination of two low‐molecular‐weight tetrabutylammonium hydroxide and 2‐methoxyethylamine surfactants for exfoliation of ZrP were found to give a CTE reduction of 40% with just 3.5 vol % of ZrP added. This CTE reduction correlates well with theory. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47703.

Structure-property relationships between microscopic filler surface chemistry and macroscopic rheological, thermo-mechanical, and adhesive performance of SiO2 filled nanocomposite underfills

SiO2 nanoparticles are attractive components for formulating highly filled underfill adhesives in the electronic packaging field. However, achieving uniform dispersion of inorganic SiO2 nanoparticles into an organic polymer matrix to obtain desired rheological and thermo-mechanical properties remains a significant challenge in nanocomposites engineering. To address the issue, previous studies mainly focused on tailoring the filler morphology and size, volume fraction and filler distribution. Here, in this work, in-situ modification of SiO2 nanoparticles by using organosilanes with different functional groups was conducted. We demonstrated the structure-property relationships between microscopic surface state of SiO2 nanofillers and macroscopic rheological, coefficient of thermal expansion (CTE) and adhesive properties of the resulting amine curing epoxy-based nanocomposite underfills. Our experimental results show that the modification of filler surface effectively enables the decrease of viscosity of underfill, and methacryl-terminated silane exhibits the highest efficiency among various organosilanes. Moreover, surface modification improves the adhesion strength between the underfill and substrate evidently, and nonpolar groups function better than their polar counterparts. In addition, modification with nonpolar methacryloxy and phenyl groups is capable of reducing CTE of nanocomposites effectively while other groups have no significant contribution to CTE reduction. These properties improvement can be attributed to the alteration of interfacial compatibility and adhesion in the SiO2 nanocomposites. Overall, our work provides a useful guideline for the rational surface chemistry design of SiO2 filler and optimizing the overall performance of underfill adhesives.

The effect of titanate nanotube/Y2W3O12 hybrid fillers on mechanical and thermal properties of HDPE-based composites

Hybrid fillers have triggered significant research in the field of polymer-based composites because they offer a range of properties that cannot be achieved by a single filler. Here a novel hybrid filler comprised of titanate nanotubes (TTNT) and Y2W3O12, a thermomiotic ceramic, was incorporated into a high density polyethylene matrix (HDPE) at an extremely low concentration (2 mass %). The influence of TTNT/Y2W3O12 mass ratio (1:1, 1:2 and 2:1), surface treatment of hybrid filler with cetyltrimethylammonium bromide (CTAB) and chemical modification of HDPE with polyethylene-grafted maleic anhydride (PE-g-MA), on the resulting mechanical and thermal properties of HDPE-based composites was investigated. The largest increase (25%) in Young’s modulus and the greatest reduction (23%) in coefficient of thermal expansion (CTE) of HDPE was achieved for 2:1 TTNT/Y2W3O12 mass ratio, without significant alteration of thermal degradation beginning or thermal conductivity of HDPE. At this optimum TTNT/Y2W3O12 mass ratio, CTAB treatment of fillers was more efficient than PE-g-MA modification of matrix promoting a better dispersion of TTNT/Y2W3O12, leading to an increase of 34% in composite stiffness and a CTE reduction of 18%, although both treatments improved hybrid filler-matrix interfaces, as judged by a rise of 6% in yield strength.

Multimodal particle distribution in 3D-SiC/Al-Si-Mg interpenetrating composite fabricated by pressureless infiltration

Mechanical failure of components used in microelectronic systems is attributed to thermal stress involving temperature fluctuations, which can be eliminated by matching the coefficient of thermal expansion (CTE) of the component parts. Low CTE and high thermal conductivity (TC) 3D-SiC/Al-Si-Mg interpenetrating composites (IPCs) with monomodal or multimodal SiC distribution were fabricated by pressurelessly infiltrating Al-15Si-10Mg into high loading 3D-SiC preforms made from either a single SiC particle size or mixed SiC particles with different sizes of F220, F800 and F1000 mesh, respectively. The effect of monomodal and multimodal SiC distribution on the TC, CTE and bending strength (BS) of the IPCs were carefully studied. In general, 3D-SiC/Al-Si-Mg IPCs with optimized multimodal SiC distribution show better comprehensive properties than 3D-SiC/Al-Si-Mg IPCs with monomodal SiC distribution. The highest TC of 233.22 W/(m °C) and BS of 283 MPa as well as lower CTE of 6.32 × 10−6 °C−1 were obtained with the bimodal 3D-SiCF220/800/Al-Si-Mg IPC having a total 73% volume fraction of F220 and F800 SiC. The use of finer F1000 SiC particles in the high loading 3D-SiC preforms could lead to finer SiC particles agglomeration and not well filling in the free space left by coarse SiC network, which result in the microstructural non-uniformity, excessive Mg2Si and retained pores in the prepared IPCs causing the weakening of strength and TC of the IPCs. A significant reduction in CTE of 5.68 × 10−6 °C−1 was achieved on trimodal 3D-SiCF220/800/1000/Al-Si-Mg IPC having a total 79% SiC volume fraction. Moreover, a new model to predict the CTE of IPC based on its 3D interpenetrating network characteristics is proposed which fits well with the experimental CTE data of the IPCs.

Mechanical and thermal properties of MoS2 reinforced epoxy nanocomposites

The effects of molybdenum disulfide (MoS2) on thermal expansion and mechanical properties of epoxy composites were investigated. MoS2 nanosheets were exfoliated by ultra-sonication and reinforced into epoxy as nanofiller by mechanical stirring. Transmission electron microscopy observations demonstrated that MoS2 exhibited better dispersion in epoxy matrix. Thermal expansion measured by dilatometer has revealed that increasing MoS2 fractioninepoxy matrix significantly reduced the coefficient of thermal expansion (CTE). The 0.5wt% MoS2 incorporated epoxy composites shows 35.8% reduction in CTE as compared to neat epoxy. The addition of small fraction of MoS2(0.1wt%) in the composites increased the tensile and flexural strength 39.2% and 9.0% respectively. The glass transition temperature (Tg) of 0.1wt% MoS2 incorporated epoxy composites shows 7.39% increase in Tg.