PMMA‐grafted‐silica/PVC nanocomposites: Mechanical performance and barrier properties

Poly(vinyl chloride) (PVC)/SiO₂ nanocomposites were prepared via melt mixture using a twin‐screw mixing method. To improve the dispersion degree of the nanoparticles and endow the compatibility between polymeric matrix and nanosilica, SiO₂ surface was grafted with polymethyl methacrylate (PMMA). The interfacial adhesion was enhanced with filling the resulting PMMA‐grafted‐SiO₂ hybrid nanoparticles characterized by scanning electron microscopy. Both storage modulus and glass transition temperature of prepared nanocomposites measured by dynamic mechanical thermal analysis were increased compared with untreated nanosilica‐treated PVC composite. A much more efficient transfer of stresses was permitted from the polymer matrix to the hybrid silica nanoparticles. The filling of the hybrid nanoparticles caused the improved mechanical properties (tensile strength, notched impact strength, and rigidity) when the filler content was not more than 3 wt %. Permeability rates of O₂ and H₂O through films of PMMA‐grafted‐SiO₂/PVC were also measured. Lower rates were observed when compared with that of neat PVC. This was attributed to the more tortuous path which must be covered by the gas molecules, since SiO₂ nanoparticles are considered impenetrable by gas molecules. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of vanadium pentoxide on the mechanical,thermal, and electrical properties of poly(vinyl alcohol)/vanadium pentoxide nanocomposites

In this study, we examined the effect of vanadium pentoxide (V₂O₅) on the mechanical, thermal, and morphological properties of poly(vinyl alcohol) (PVA)/V₂O₅ nanocomposites. The PVA/V₂O₅ nanocomposites were prepared by solution mixing, followed by film casting. The results show that the Young's moduli of the resulting nanocomposites films were higher than the pure PVA modulus with increasing V₂O₅ content, and it reached a maximum point at about 0.4 wt % V₂O₅ content at 8.55 GPa. The tensile strength and stress at break increased with increasing V₂O₅ content. The addition of V₂O₅ did not affect the melting temperature. The crystallization temperatures of PVA were significantly changed with increasing V₂O₅ content. The 5% weight loss degradation temperature of the nanocomposites was measured by thermogravimetric analysis. The degradation temperatures of the V₂O₅ nanocomposites increased with increasing filler content and were higher than the degradation temperature of pure PVA; this showed a lower thermal stability compared to those of the nanocomposites. The results show that the thermal stability increased with the incorporation of V₂O₅ nanoparticles. The dielectric constant of PVA had a tendency to improve when the dispersion of particles was effective. The morphology of the surfaces the nanocomposites was examined by scanning electron microscopy. We observed that the dispersion of the V₂O₅ nanoparticles was relatively good; only few aggregations existed after the addition of the V₂O₅ nanoparticles at greater than 0.4 wt %. In perspective, the addition of 0.4 wt % V₂O₅ nanoparticles into PVA maximized the mechanical, thermal, and electrical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effects of SiO2 and Al2O3 nanofillers on polyethylene properties

Polymers filled with inorganic nanoparticles have become interesting materials as dielectrics because of their improved mechanical and electrical properties compared with the unfilled polymers and with polymer microcomposites. These improvements are mainly due to the large surface area of nanoparticles and new polymer–nanofiller interface characteristics. In the present work, polyethylene nanocomposites with SiO₂ and Al₂O₃ nanoparticles were prepared by melt mixing. Mechanical and electrical properties of these composites were determined and morphological aspects were revealed by scanning electron microscopy, wide‐angle X‐ray diffraction, and atomic force microscopy. The effect of nanostructure and the importance of nanofiller dispersion were analyzed in connection with mechanical and electrical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermophysical properties of foliated graphite/nickel reinforced polyvinyl chloride nanocomposites

A novel, polymer‐based foliated graphite/nickel nanocomposites with high thermal conductivity, mechanical properties, and low dielectric constant was developed. The network structure of polyvinyl chloride (PVC) reinforced foliate graphite and nickel nanoparticles (GN) were tested in terms of X‐ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive x‐ray analysis (EDX), and thermal‐gravimetric analyses (TGA). Thermogravimetric analysis revealed a large improvement in the thermal stability of PVC/GN nanocomposites. Thermal conductivity and diffusivity of the composites increased with increasing GN content and temperature. The obtained experimental thermal conductivity result are compared with the existing theoretical models. The measured values of thermal conductivity were in excellent agreement with those calculated from the Agari model. In addition, specific heat, coefficient of thermal expansion (TEC), micro porosity, and crosslinking density (CLD) of composites were investigated. The mechanical properties such as tensile strength, tensile modulus, hardness, and elongation at break of the nanocomposites were improved with inclusion GN which is proportional to GN content. Finally, the dielectric properties of PVC/GN nanocomposites as a function of frequency have been investigated in details. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis,characterization, and properties of cashew gum graft poly(acrylamide)/magnetite nanocomposites

Graft copolymer nanocomposites based on cashew gum and poly(acrylamide) with different concentrations of nano‐iron‐oxide particles (Fe₃O₄) have been prepared by an in situ polymerization method. The characterization of graft copolymer composite was carried out by FTIR, UV, XRD, SEM, DSC, and TGA, electrical conductivity, and magnetic property [vibrational sample magnetometer (VSM)] measurements. The shift in the spectrum of UV and FTIR peaks shows the intermolecular interaction between metal oxide nanoparticles and the graft copolymer system. The spherically shaped particles observed from the SEM images clearly indicating the uniform dispersion of nanoparticles within the graft copolymer chain. The XRD studies revealed that the amorphous nature of the graft copolymer decreases by the addition of Fe₃O₄ nanoparticles. The glass transition temperature studied from DSC increases with increase in concentration of metal oxide nanoparticles. Thermal stability of composite was higher than the pure graft copolymer and thermal stability increases with increase in content of nanoparticles. Electrical properties such as AC conductivity and dielectric properties of the composites increased with increase in concentration of metal oxide nanoparticles. The magnetic property of graft copolymer nanocomposites shows ferromagnetic and supermagnetism and the saturation of magnetism linearly increased with increasing the Fe₃O₄ content in the polymer composite. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43496.     

Synergistic effect of carbon nanofiber decorated with iron oxide in enhancing properties of styrene butadiene rubber nanocomposites

Elastomer nanocomposites reinforced with carbon nanofiber (CNF) decorated with metal nanoparticles exhibit excellent thermal, mechanical, and magnetic properties with low volume fraction of the reinforcement. Generally, metal nanoparticles are used to modify the surface of CNF, to improve their dispersion and contact resistance in the polymer matrix. In this study, Fe₂O₃ metal nanoparticles were decorated on CNF by electrostatic attraction via a green and facile solution‐based method. Interestingly, the CNF decorated with Fe₂O₃ (CNF‐Fe₂O₃)/elastomer improved both the tensile strength and the fatigue property of plain CNF/elastomer by as much as 57.2% and 27.2%, respectively. Moreover, the CNF‐Fe₂O₃/elastomer exhibited superior thermal conductivity, a twofold enhancement compared with carbon fibers. The elastomer nanocomposites consisting of CNF‐Fe₂O₃ also exhibited enhanced magnetic properties due to synergies between the Fe₂O₃ nanoparticles and the CNF. The elastomer nanocomposites prepared with CNF‐Fe₂O₃ will open significant new opportunities for preparing advanced elastomer nanocomposites for future engineering applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45376.     

Dielectric,thermal and mechanical properties of hybrid PMMA/RGO/Fe2O3 nanocomposites fabricated by in-situ polymerization

Currently, the organic-inorganic hybrid materials have gained tremendous importance due to their unique applications in different technological fields. In this connection, the chemical synthesis of poly(methyl methacrylate) (PMMA) and its binary and ternary nanocomposites by in-situ bulk polymerization with various percentages of reduced graphene oxide (RGO) and hematite nanoparticles (Fe₂O₃ NPs) is presented. Dielectric properties of binary and ternary nanocomposites are investigated in the frequency range of 25 Hz-1 MHz for each composition. Ternary nanocomposite of PMMA with RGO:Fe₂O₃ NPs (2:2 wt%) exhibits a substantial enhancement of the dielectric constant up to ≈308 and suppressed dielectric loss of 0.12 at 25 Hz. Appearance of three types of interfaces in ternary PMMA nanocomposites accounts for the superior dielectric properties due to the accumulation of greater number of charges at the interfaces as compared to the binary nanocomposites with only one interface. The same optimized ternary PMMA nanocomposite shows a remarkable improvement in the thermal conductivity (2.04 W/mK), which is attributed to the formation of efficient thermal conducting pathways contributed by the synergic reduction in thermal resistance of both RGO and Fe₂O₃ NPs (2:2 wt%) relative to the binary nanocomposites PMMA/2 wt% RGO (1.04 W/mK) and PMMA/2 wt% Fe₂O₃ (0.98 W/mK). Thus, ternary nanocomposites prove to be the excellent candidates for thermal management applications. Furthermore, a comparison of the mechanical strength and thermal stability for all the binary and ternary nanocomposites is presented. In the last section, respective precursors and optimized binary and ternary nanocomposites are characterized by XRD, FTIR and SEM which reveal the strong interaction of respective nanofillers into PMMA matrix.     

Rheological and mechanical properties of PVC/CaCO3 nanocomposites prepared by in situ polymerization

Poly(vinyl chloride) (PVC)/calcium carbonate (CaCO₃) nanocomposites were synthesized by in situ polymerization of vinyl chloride (VC) in the presence of CaCO₃ nanoparticles. Their thermal, rheological and mechanical properties were evaluated by dynamic mechanical analysis (DMA), thermogravimetry analysis (TGA), capillary rheometry, tensile and impact fracture tests. The results showed that CaCO₃ nanoparticles were uniformly distributed in the PVC matrix during in situ polymerization of VC with 5.0 wt% or less nanoparticles. The glass transition and thermal decomposition temperatures of PVC phase in PVC/CaCO₃ nanocomposites are shifted toward higher temperatures by the restriction of CaCO₃ nanoparticles on the segmental and long-range chain mobility of the PVC phase. The nanocomposites showed shear thinning and power law behaviors. The ‘ball bearing’ effect of the spherical nanoparticles decreased the apparent viscosity of the PVC/CaCO₃ nanocomposite melts, and the viscosity sensitivity on shear rate of the PVC/CaCO₃ nanocomposite is higher than that of pristine PVC. Moreover, CaCO₃ nanoparticles stiffen and toughen PVC simultaneously, and optimal properties were achieved at 5 wt% of CaCO₃ nanoparticles in Young's modulus, tensile yield strength, elongation at break and Charpy notched impact energy. Detailed examinations of micro-failure micromechanisms of impact and tensile specimens showed that the CaCO₃ nanoparticles acted as stress raisers leading to debonding/voiding and deformation of the matrix material around the nanoparticles. These mechanisms also lead to impact toughening of the nanocomposites.     

Effect of shell phase composition on the dielectric property and energy density of core-shell structured BaTiO3 particles modified poly(vinylidene fluoride) nanocomposites

Dielectric nanocomposites have attracted much attention due to their wide applications in electronics and electrical industry. Recently, incorporating core-shell nanoparticles into polymer matrix to improve the dielectric properties of nanocomposites has been widely reported. Tailoring the interfacial region between the polymer and the nanoparticles plays a crucial role in achieving the desired dielectric and energy storage properties of nanocomposites. However, the effect of shell structure in the interface region on the dielectric and energy storage properties is rarely studied. Based on this, core-shell BaTiO₃ nanoparticles with two different shell polymers, a “hard-soft” copolymer of methyl methacrylate and butyl acrylate (P[MMA-BA]) and a “hard” homopolymer of methyl methacrylate (PMMA), were prepared in this paper. The effect of core-shell BaTiO₃ nanoparticles with different shell structures on the dielectric and energy storage properties of poly(vinylidene fluoride) (PVDF) was investigated in depth. Due to the formation of a tight interfacial region between P(MMA-BA)@BT and PVDF matrix, P(MMA-BA)@BT/PVDF nanocomposites not only have low dielectric loss but also higher energy efficiency than PMMA@BT/PVDF nanocomposites. This study suggests a potential strategy that fabricating a “hard-soft” copolymer shell on BaTiO₃ surface can obtain desirable energy storage efficiency than the single “hard” shell structure in dielectric nanocomposites.     

Nanocomposites of PVC/TiO2 nanorods: Surface tension and mechanical properties before and after UV exposure

In this study, nanocomposites of poly(vinyl chloride) (PVC), using the synthesized titanium dioxide (TiO₂) nanorods and commercial nanopowder of titanium dioxide (Degussa P25) were produced by melt blending. The presence of TiO₂ nanorods in PVC matrix led to an improvement in mechanical properties of PVC nanocomposites in comparison with unfilled PVC. The photocatalytic degradation behavior of PVC nanocomposites were investigated by measuring their structural change evaluations, surface tension, and mechanical properties before and after UV exposure for 500 h. It was found that mechanical and physical properties of PVC nanocomposites are not reduced significantly after UV exposure in the presence of TiO₂ nanorods in comparison with the presence of TiO₂ nanoparticles, which can be due to the amorphous structure of the synthesized nanorods. Therefore, it can be concluded that TiO₂ nanorods led to an improvement in photostability and mechanical properties of PVC nanocomposites. The interfacial adhesion between TiO₂ nanorods and PVC matrix was also investigated. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

LDPE/Bi2O3 nanocomposites: Enhanced mechanical,dielectric, and optical properties

This study is focused on investigating the role of bismuth oxide (Bi₂O₃) nanoparticles to improve structural, optical, electrical, and mechanical properties of low-density polyethylene (LDPE). For this purpose, Bi₂O₃ nanoparticles were synthesized by using the solvothermal method and examined by transmission electron microscopes (TEM), x-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, and ultraviolet–visible (UV–Vis) light absorption methods. LDPE-based nanocomposites were prepared by changing the nanoparticle additive ratio in the composite from 0% to 2% by weight. The composites were analyzed in the context of their FTIR spectra, atomic force microscope (AFM) images, UV–Vis light absorption spectra, stress–strain curves, and energy storage abilities. While the AFM findings indicate a smoother surface for the composites, the optical band gap analysis reveals a slightly decreased direct optical band gap energy. The analyses based on dielectric spectroscopy also highlight the LDPE/0.5% n-Bi₂O₃ composite in terms of the best energy storage capability. Additionally, the highest Young's modulus, toughness, stress at break, and percentage of strain at break were also recorded for the LDPE/0.5% n-Bi₂O₃ composite. In this context, the LDPE/0.5% n-Bi₂O₃ composite with improved dielectric and mechanical properties can be suggested as a new promising LDPE-based nanocomposite with better properties for industrial purposes.     

Effects of graphene nanosheets on the dielectric,mechanical, thermal properties,and rheological behaviors of poly(arylene ether nitriles)

Poly(arylene ether nitriles) (PEN) containing various contents of graphene nanosheets (GNs) was prepared via solution‐casting method and investigated for their dielectric, mechanical, thermal, and rheological properties. For PEN/GNs nanocomposite with 5 wt % GNs, the dielectric constant was increased to 9.0 compared with that of neat PEN (3.1) and dielectric losses of all nanocomposites were in the range of 0.019–0.023 at 1 kHz. The tensile modulus and strength were increased about 6 and 14% with 0.5% GNs, respectively. The fracture surfaces of the all PEN/GNs nanocomposites revealed that GNs had good adhesion to PEN matrix. The thermal properties of the nanocomposites showed significant increase with increasing GN loading. For 5 wt % GNs‐reinforced PEN nanocomposite, the temperatures corresponding to a weight loss of 5 wt % (T_d5%) and 30 wt % (T_d30%) increased by about 20 and 13°C, respectively. Rheological properties of the PEN nanocomposites showed a sudden change with the GN fraction and the percolation threshold was about 1 wt % of GNs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Design and fabrication of flexible poly(vinyl chloride) dielectric composite reinforced with ZnO microvaristors

Flexible poly(vinyl chloride)/varistor composites were fabricated by solution casting method. High‐field ZnO varistor particles processed from micron‐sized Zn dust is explored as multifunctional filler for PVC composites. Mechanical blending of Zn dust with La₂O₃‐CeO₂ rare earths and varistor forming minor additives followed by sintering at 1250 °C resulted in fine‐grained ZnO varistors. Bulk varistor was subsequently milled to obtain ZnO microvaristor grains. The effect of microvaristor on the UV stability, dielectric, and mechanical properties of the PVC composite was analyzed. The varistor filler in PVC enhanced the microhardness and retained the tensile properties without any significant loss. After UV irradiation PVC/varistor composite shows remarkable mechanical stability retention (95%) compared to pure PVC (75%). Also, microvaristor reinforcement resulted in dielectric constant tunability (? = 2–37) without any drastic change in the dielectric loss (0.02–0.05). Thus, Zn dust‐derived ZnO varistors could be potentially exploited to design functional PVC composites for electronic applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46031.     

Effect of neodymium‐doped titanium dioxide nanoparticles on the structural,mechanical, and electrical properties of poly(butyl methacrylate) nanocomposites

Nanocomposites based on neodymium‐doped titanium dioxide (Nd‐TiO₂)/poly(n‐butyl methacrylate) (PBMA) have been prepared by an in situ polymerization of butyl methacrylate monomer with varying concentrations of Nd‐TiO₂ nanoparticles. The resulting nanocomposites have been analyzed by ultraviolet (UV)–Visible spectroscopy, Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis, and impedance analyzer (TGA). The results of UV and FTIR spectroscopy have indicated the interaction of nanoparticles with the PBMA matrix. Spherically shaped nanoparticles with an average size of 10–25 nm have been revealed in the TEM and their homogeneous dispersion, and interaction of polymer matrix has been confirmed by SEM and XRD studies. The thermal stability and glass transition temperature of the composites were significantly enhanced by the addition of nanoparticles. The AC conductivity and dielectric properties of nanocomposites have been found to be higher than pure PBMA, and the maximum electrical properties have been observed for 7 wt% composite. The reinforcing nature of the nanoparticles in PBMA has been reflected in the improvement in tensile strength measurements. The result indicated that the tensile strength of nanocomposites have greatly enhanced by the addition of Nd‐TiO₂ nanoparticles whereas the elongation at break decreases with the loading of nanofillers. To understand the mechanism of reinforcement, tensile strength values have been correlated with various theoretical modeling. The research has been found to be promising in the development of novel materials with enhanced tensile strength, dielectric constant, and thermal properties, which may find potential applications in energy storage and nanoelectronic devices. J. VINYL ADDIT. TECHNOL., 25:9–18, 2019. © 2018 Society of Plastics Engineers     

Hybridizing MWCNT with nano metal oxides and TiO2 in epoxy composites: Influence on mechanical and thermal performances

In this study, the effects of multi‐walled carbon nanotubes (MWCNT), and its hybrids with iron oxide (Fe₂O₃) and copper oxide (CuO) nanoparticles on mechanical characteristics and thermal properties of epoxy binder was evaluated. Furthermore, simultaneous effects of using MWCNT with TiO₂ as pigment and CaCO₃ as filler for epoxy composites were determined. To investigate effects of nano‐ and micro‐particles on epoxy matrix, the samples were evaluated by TGA and DTA. It was found that the hybrid of MWCNT with nano metal oxides caused considerable increment in the tensile and flexural properties of epoxy samples in comparison to the single MWCNT containing samples at the same filler contents. Significant improvement in the thermal conductivity of epoxy samples was obtained by using TiO₂ pigment along with MWCNT. The TiO₂ pigment also caused considerable improvement in mechanical properties of the epoxy matrix and the MWCNT containing nanocomposite. The best mechanical and thermal properties of epoxy nanocomposites were obtained at 1.5 wt % of MWCNT and 7 wt % of TiO₂ that it should be attributed to particle network forming of the particles which cause better nano/micro dispersion and properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43834.     

Novel electromagnetic interference shielding effectiveness in the microwave band of magnetic nitrile butadiene rubber/magnetite nanocomposites

A novel nitrile butadiene rubber (NBR)/magnetite (Fe₃O₄) nanocomposite for electromagnetic interference (EMI) shielding at microwave frequency was successfully fabricated. The structural features of as-synthesized magnetite and NBR/Fe₃O₄ were examined by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The number of elastically effective chains, volume fraction of rubber, interparticle distance among conductive sites, polymer–filler interaction, and porosity of the nanocomposites were evaluated. The mechanical properties, including the tensile strength, elongation at break, and hardness, of the composites were measured. The static electrical properties, such as the electrical conductivity, carrier mobility, and number of charge carriers, as a function of magnetite content were evaluated. The interrelation between the electrical conductivity, shielding effectiveness (SE), dielectric constant, and skin depth of the composites are discussed. Finally, the EMI SE versus frequency was tested. The results reveal that an SE of 28–91 dB against EMI in the 1–12 GHz range depended on the loading of the conducting magnetite within the NBR matrix. Accordingly, these nanocomposites may used in the field of microwave absorption devices. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Structure-property relationships of in-situ PMMA modified nano-sized antimony trioxide filled poly(vinyl chloride) nanocomposites

Nano-sized antimony trioxide (Sb₂O₃) particles were modified by in-situ methyl methacrylate (MMA)/Sb₂O₃ polymerization. Subsequently, these modified nanoparticles were compounded with poly(vinyl chloride) (PVC) to prepare PVC/Sb₂O₃ nanocomposites. In-situ MMA/Sb₂O₃ polymerization kinetics shows that nano-Sb₂O₃ particles do not inhibit polymerization of MMA. PMMA shell covered on the surface of nano-sized Sb₂O₃ particles have enhanced interactions with PVC matrix, breaking down nano-Sb₂O₃ particle agglomerates and improving their dispersion in the matrix (average particle size of 60-80 nm) and also increasing the particle-matrix interfacial adhesion. Thus, nano-Sb₂O₃ particles reinforce and toughen PVC. It was observed that at 2.5 wt% of nano-Sb₂O₃ particles modified by in-situ PMMA optimal properties were achieved in Young's modulus, tensile yield strength, elongation at break and Charpy notched impact strength. Detailed examinations of micro-failure mechanisms of tensile specimens showed that nano-Sb₂O₃ particles acted as stress concentrators leading to debonding/voiding and deformation of the matrix material around the nanoparticles. Under impact fracture, the nano-Sb₂O₃ particles prolonged crack initiation time, and increased energy absorptions for crack initiation and fracture propagation caused by strong interfacial interaction between nanoparticles and PVC matrix. These mechanisms lead to impact toughening of the nanocomposites.     

Understanding the effect of nanoparticles TiO2, Al2O3 and SiO2 on damage mechanisms of a polymer composite

In this paper, nanoparticles obtained by Sol-gel method have been incorporated as a filler in glass fiber/polyester composite in order to improve the mechanical properties of the resulting material. This work covered on the characterization and the study of the polymer matrix with 5 wt.%nano TiO₂, 5 wt.%nano Al₂O₃, 5 wt.%nano SiO₂.The results obtained revealed that sol-gel powders with a spherical morphology have excellent thermal stability. Acoustic emission analysis was used to investigate the microscopic damage mechanisms and progression in glass fiber reinforced nanocomposites. Thus, acoustic emission from four modes of approval has been identified: matrix cracking, matrix/fiber decohesion, delamination and fiber breakage. This study shows the increase of mechanical performance and the decrease of damage modes of @Polyester. From the SEM images, the good dispersion of nanofillers, absence of agglomerates, the good affinity with the improving of the interface compatibility were presented.     

Epoxy Composites Reinforced with Negative‐CTE ZrW2O8 Nanoparticles for Electrical Applications

The potential for incorporating negative‐CTE zirconium tungstate (ZrW₂O₈) nanoparticles in an epoxy matrix with the aim of developing epoxy/ZrW₂O₈ nanocomposites with tailored CTE values for electrical applications is investigated. The ZrW₂O₈/epoxy nanocomposites are prepared through incorporation of up to 20 vol% unfunctionalized nanoparticles or silane‐functionalized nanoparticles containing either epoxy or amine end groups. Improvements in thermomechanical and dynamic mechanical properties of the epoxy matrix are achived with no detrimental effect on the dielectric strength, which suggests that these nanocomposites could be viable candidates for a wide range of electrical applications.

     

Synthesis and characterization of (Fe3O4/MWCNTs)/ epoxy nanocomposites

A sonochemical technique is used for in situ coating of iron oxide (Fe₃O₄) nanoparticles on outer surface of MWCNTs. These Fe₃O₄/MWCNTs were characterized using a high‐resolution transmission electron microscope (HRTEM), X‐ray diffraction, and thermogravimetric analysis. The as‐prepared Fe₃O₄/MWCNTs composite nanoparticles were further used as reinforcing fillers in epoxy‐based resin (Epon‐828). The nanocomposites of epoxy were prepared by infusion of (0.5 and 1.0 wt %) pristine MWCNTs and Fe₃O₄/MWCNTs composite nanoparticles. For comparison purposes, the neat epoxy resin was also prepared in the same procedure as the nanocomposites, only without nanoparticles. The thermal, mechanical, and morphological tests were carried out for neat and nanocomposites. The compression test results show that the highest improvements in compressive modulus (38%) and strength (8%) were observed for 0.5 wt % loading of Fe₃O₄/MWCNTs. HRTEM results show the uniform dispersion of Fe₃O₄/MWCNTs nanoparticles in epoxy when compared with the dispersion of MWCNTs. These Fe₃O₄/MWCNTs nanoparticles‐infused epoxy nanocomposite shows an increase in glass transition (T_g) temperature. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010