Mechanical properties of epoxy resins reinforced with synthetic boehmite (AlOOH) nanosheets

In this article, sheet boehmite (AlOOH), which was synthesized via a facile and environmental friendly method, was used as reinforcing agent to toughen Bisphenol A epoxy resin. The result of X–ray Diffraction (XRD) and IR spectrum indicated that the as–synthesized product was pure crystalline and high purity AlOOH. The effects of sheet AlOOH on the mechanical properties of AlOOH/epoxy nanocomposites were investigated. The results indicated that the introduction of AlOOH significantly improved the mechanical properties of epoxy resin. Compared with neat epoxy resin, the tensile strength and the fracture toughness (K_IC) of the AlOOH/epoxy nanocomposites filled with 4 wt % AlOOH increased by 24.2% and 28.7%, respectively, while the flexural strength increased from 40.92 to 50.00 MPa. From Scanning Electron Microscope (SEM), a phase‐separated morphology and plenty of cervices and river branches were observed in the fractured surfaces of composites. With the increase of sheet AlOOH content, river‐shaped cracks became more and more intensive. Overall, the addition of sheet AlOOH is shown as a promising method for mechanical properties enhancement of epoxy matrix. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41409.     

High‐performance flexible epoxy/ZnO nanocomposites with enhanced mechanical and thermal properties

Flexible epoxy/ZnO nanocomposites were prepared using different loadings of ZnO nanoparticles (NPs) and nanotubes (NTs) via in situ curing of epoxy with polyoxyethylene diamines (ED₆₀₀). ZnO precursor was synthesized via precipitation method and ZnO NPs with an average size of 25 nm were used in the preparation of the nanocomposites. ZnO NTs with an average outer diameter, length of 200 nm and 2.4 µm respectively, were prepared by the wet method (hydrothermal method). The morphology, structure, and composition of the nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), and thermo‐gravimetric analysis (TGA). The effect of morphology and content of nano‐ZnO materials on the thermal and mechanical properties of flexible epoxy was studied. In addition, the hardness and indentation depth were calculated by means of nanoindentation. Results showed that the mechanical and thermal properties of flexible epoxy were enhanced by incorporation of ZnO nanostructure into the polymer matrix. POLYM. ENG. SCI., 57:932–946, 2017. © 2016 Society of Plastics Engineers     

Reinforcing effect of organoclay in rubbery and glassy epoxy resins,part 1: Dispersion and properties

The reinforcing effect of organoclay in two epoxy matrices, one rubbery and one glassy, was studied. The rubbery and glassy epoxy matrices were chosen to have a very similar chemistry to minimize its impact on the comparison of properties. The epoxy resin was EPON? 828, and the two hardeners were amine‐terminated polyoxypropylene diols, having different average molecular weights (MW) of 2000 and 230 g/mol, namely Jeffamine® D‐2000 and Jeffamine® D‐230, respectively. The nanocomposites were prepared with the organoclay Cloisite® 30B from Southern Clay Products. The quality of dispersion and intercalation/exfoliation was analyzed by means of X‐ray diffraction (XRD), field emission gun scanning electron microscopy (FEGSEM), and transmission electron microscopy (TEM). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to study the curing reactivity and the thermal stability of the epoxy resin systems, respectively. Tensile properties and hardness of epoxy resin and epoxy nanocomposites were measured according to ASTM standards D638‐02 and D2240‐00, respectively. Fracture surfaces were also analyzed by FEGSEM. These two epoxy systems as well as their nanocomposites display totally different physical and mechanical behavior. It is found that the quality of clay dispersion and intercalation/exfoliation, and the mechanical behavior of the glassy and rubbery epoxy nanocomposites are distinct. The results also indicate that the presence of the clay does not significantly affect the T_g of either the rubbery or the glassy epoxy; however, the fracture surface and mechanical properties were found to be influenced by the presence of nanoclay. Finally, several different reinforcing mechanisms are proposed and discussed for the rubbery and glassy epoxy nanocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Ternary nanocomposites based on epoxy,modified silica,and tetrabutyl titanate: Morphology,characteristics, and kinetics of the curing process

In this study, the effects of unmodified nanosilica and nanosilica modified by an isopropyl tri[di(octyl) phosphate] titanate coupling agent (KR-12; m-nanosilica) on the structure, morphology, thermomechanical properties, and kinetics of the curing process of epoxy–tetrabutyl titanate (TBuT) nanocomposites were investigated. The viscosity, tensile strength, and flexural strength of the cured epoxy and cured epoxy–m-silica–TBuT nanocomposites were determined with a Brookfield viscometer and an Instron 5582-100KN universal machine. The morphology and gel fraction content of the nanocomposites were analyzed with transmission electron microscopy and scanning electron microscopy methods and Soxhlet extraction. The viscosity, mechanical properties, gel fraction content, and morphology results of the cured epoxy–m-silica–TBuT nanocomposites confirm that 5 wt % m-nanosilica was the most suitable for improving the dispersion of m-nanosilica in the epoxy matrix and the properties of these materials. The thermal behavior of the nanocomposites was determined by thermogravimetric analysis and differential scanning calorimetry (DSC) methods. On the basis of DSC data, the average value of the activation energy of the cured epoxy–TBuT system, calculated according to Flynn–Wall–Ozawa and Kissinger equations, was 67.893 kJ/mol. The calculation according to the Crane equation showed that the first-order kinetics complied with the curing reaction for the neat epoxy. When we introduced the unmodified nanosilica and modified nanosilica into the epoxy matrix, the order kinetics of the curing reaction for the nanocomposites also followed first-order kinetics, but the activation energy of their curing reaction decreased significantly. Some other properties were also investigated with dynamic mechanical analysis and Fourier transform infrared analysis and are discussed. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47412.     

Properties of a reactive‐graphitic‐carbon‐nanofibers‐reinforced epoxy

Our previous studies showed that herringbone graphitic GNFs surface‐derivatized with reactive linker molecules bearing pendant primary amino functional groups capable of binding covalently to epoxy resins. Of special importance, herringbone GNFs derivatized with 3,4′‐oxydianiline (GNF‐ODA) were found to react with neat butyl glycidyl ether to form mono‐, di‐, tri‐, and tetra‐glycidyl oligomers covalently coupled to the ODA pendant amino group. The resulting reactive GNF‐ODA (butyl glycidyl)_n nanofibers, r‐GNF‐ODA, are especially well suited for reactive, covalent incorporation into epoxy resins during thermal curing. Based on these studies, nanocomposites reinforced by the r‐GNF‐ODA nanofibers at nanofiber loadings of 0.15–1.3 wt% were prepared. Flexural property of cured r‐GNF‐ODA/epoxy nanocomposites were measured through three‐point‐bending tests. Thermal properties, including glass transition temperature (T_g) and coefficient of thermal expansion (CTE) for the nanocomposites, were investigated using thermal mechanical analysis. The nanocomposites containing 0.3 wt% of the nanofibers gives the highest mechanical properties. At this 0.3‐wt% fiber loading, the flexural strength, modulus and breaking strain of the particular nanocomposite are increased by about 26, 20, and 30%, respectively, compared to that of pure epoxy matrix. Moreover, the T_g value is the highest for this nanocomposite, 14°C higher than that of pure epoxy. The almost constant change in CTEs before and after T_g, and very close to the change of pure epoxy, is in agreement with our previous study results on a chemical bond existing between the r‐GNF‐ODA nanofibers and epoxy resin in the resulting nanocomposites. POLYM. COMPOS., 28:605–611, 2007. © 2007 Society of Plastics Engineers     

Mechanical,thermomechanical, and creep performance of CNT embedded epoxy at elevated temperatures: An emphasis on the role of carboxyl functionalization

In contrast to polymeric composites, the role of interface/interphase has been widely acknowledged to govern their overall properties and performance. Environmental temperature has substantial effects on the interfacial durability of polymer nanocomposites. In this regard, present investigation has been carried out to study the mechanical performance of pristine (UCNT) and carboxylic functionalized CNT (FCNT) embedded epoxy nanocomposites under different elevated temperatures. Higher flexural strength and modulus of FCNT‐EP nanocomposite were recorded over UCNT‐EP and neat epoxy at room temperature environment. Flexural testing at elevated temperatures revealed a higher rate of strength degradation in polymer nanocomposites over neat epoxy. Postfailure analysis of specimens has been conducted to understand the alteration in failure micro‐mechanisms upon UCNTs and FCNTs addition in epoxy. Variation in viscoelastic properties with temperature has been studied from dynamic mechanical thermal analysis and significant reduction in glass transition temperature (T_g) is observed for nanocomposites. In the studied temperature and stress combinations, FCNT‐EP nanocomposites exhibited better creep resistance over UCNT‐EP and neat epoxy. Room temperature strengthening, elevated temperature strength degradations, improved creep resistance and reduction in T_g in nanocomposites over neat polymer have been discussed in terms of dynamic nature and gradient structure of CNT/epoxy interphase. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44851.     

Preparation and mechanical properties of epoxy/diamond nanocomposites

Nanodiamond (ND) has recently attracted much attention for its outstanding mechanical and other interesting properties. Surface functionalization of ND is necessary for applications in polymers. In this study, ND particles were functionalized with amine by covalent linking of triethylene tetramine, and further grafted with epoxy which was cured with amine curing agent. The particle dispersion and mechanical properties of epoxy/ND nanocomposites were evaluated. Both fracture toughness and storage modulus of epoxy resin were significantly improved with a low loading of ND‐NH₂ particles. The morphological structure of the epoxy/ND nanocomposites was examined, and toughening mechanism was explored. POLYM. COMPOS., 35:2144–2149, 2014. © 2014 Society of Plastics Engineers     

Improved mechanical and thermal properties of bamboo–epoxy nanocomposites

Natural fiber‐reinforced hybrid composites based on bamboo/epoxy/nanoclay were prepared. Ultrasound sonication was used for the dispersion of nanoclay in the bamboo–epoxy composites. The morphology of bamboo–epoxy nanocomposites was investigated by using scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction. The results show that there exists an optimum limit in which the mechanical properties of composites improved by continuously increasing the nanoclay content. The tensile and flexural strength of bamboo–epoxy nanocomposites with 3 wt% nanoclay increased by 40% and 27%, respectively, as compared to pure composites. The highest value of impact strength was obtained for 1 wt% nanoclay content bamboo–epoxy nanocomposites. The enhanced impact strength of bamboo–epoxy nanocomposites was one of the key advantages brought by nanofiller. The results show that incorporation of nanoclay substantially increases the water resistance capability and thermal stability of bamboo–epoxy nanocomposites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Morphology and mechanical and viscoelastic properties of rubbery epoxy/organoclay montmorillonite nanocomposites

The morphology and mechanical and viscoelastic properties of rubbery epoxy/organoclay montmorillonite (MMT) nanocomposites were investigated with wide‐angle X‐ray scattering (WAXS), transmission electron microscopy (TEM), tensile testing, and dynamic mechanical thermal analysis. An ultrasonicator was used to apply external shearing forces to disperse the silicate clay layers in the epoxy matrix. The first step of the nanocomposite preparation consisted of swelling MMT in a curing agent, that is, an aliphatic diamine based on a polyoxypropylene backbone with a low viscosity for better diffusion into the intragalleries. Then, the epoxy prepolymer was added to the mixture. Better dispersion and intercalation of the nanoclay in the matrix were expected. The organic modification of MMT with octadecylammonium ions led to an increase in the initial d‐spacing (the [d₀₀₁] peak) from 14.4 to 28.5 Å, as determined by WAXS; this indicated the occurrence of an intercalation. The addition of 5 phr MMTC18 (MMT after the modification) to the epoxy matrix resulted in a finer dispersion, as evidenced by the disappearance of the diffraction peak in the WAXS pattern and TEM images. The mechanical and viscoelastic properties were improved for both MMT and MMTC18 nanocomposites, but they were more pronounced for the modified ones. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 103: 3547–3552, 2007     

Light‐curing of a sol–gel‐derived silicate‐based epoxy‐functional polymer nanocomposite material system

In an effort to explore the potential of certain types of polymer nanocomposites to be successful candidates as dental restoration/adhesion materials, a Ti‐ or Zr‐containing and organically modified silicate‐based material system with epoxy functionality was prepared by use of a sol–gel synthesis method, and ultraviolet light‐ and visible light (VL)‐curing processes. Comparative influences of certain synthesis/processing parameters on the properties of the system were detailed. It was shown that both Ti‐ and Zr‐containing species could play significant roles in determining the structure and hence the properties of the nanocomposites. VL‐curing was demonstrated to be a relatively advantageous process that could be employed in applications such as dental restoration/adhesion. Moreover, the mechanical properties of the nanocomposites were shown to be promisingly high. Overall observations and results indicated a prospective opportunity for this material system to be utilized in dental restoration/adhesion applications. POLYM. COMPOS., 35:1879–1887, 2014. © 2014 Society of Plastics Engineers     

Preparation and optical properties of transparent epoxy composites containing ZnO nanoparticles

Polymer nanocomposites are usually made by incorporating dried nanoparticles into polymer matrices. This way not only leads to easy aggregation of nanoparticles but also readily brings about opaqueness for nanocomposites based on functionally transparent polymers. In this letter, transparent ZnO/epoxy nanocomposites with high‐UV shielding efficiency were prepared via two simple steps: first, in situ preparation of zinc hydroxide (Zn(OH)₂)/epoxy from the reaction of aqueous zinc acetate (Zn(Ac)₂·2H₂O) and sodium hydroxide (NaOH) at 30°C in the presence of high‐viscosity epoxy resin; second, thermal treatment of the as‐prepared Zn(OH)₂/epoxy hybrid into ZnO/epoxy composites. Optical properties of the resultant ZnO/epoxy nanocomposites were studied using an ultraviolet–visible (UV–vis) spectrophotometer. The nanocomposites containing a very low content of ZnO nanoparticles (0.06 wt %) possessed the optimal optical properties, namely high‐visible light transparency and high‐UV light shielding efficiency. Consequently, the as‐prepared ZnO/epoxy nanocomposites are promising for use as novel packaging materials in lighting emitting diodes technology. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Mechanical and morphological properties of organic–inorganic,hybrid, clay‐filled,and cyanate ester/siloxane toughened epoxy nanocomposites

Organic–inorganic hybrids involving cyanate ester and hydroxyl‐terminated polydimethylsiloxane (HTPDMS) modified diglycidyl ether of bisphenol A (DGEBA; epoxy resin) filled with organomodified clay [montmorillonite (MMT)] nanocomposites were prepared via in situ polymerization and compared with unfilled‐clay macrocomposites. The epoxy‐organomodified MMT clay nanocomposites were prepared by the homogeneous dispersion of various percentages (1–5%), and the resulting homogeneous epoxy/clay hybrids were modified with 10% HTPDMS and γ‐aminopropyltriethoxysilane as a coupling agent in the presence of a tin catalyst. The siliconized epoxy/clay prepolymer was further modified separately with 10% of three different types of cyanate esters, namely, 4,4′‐dicyanato‐2,2′‐diphenylpropane, 1,1′‐bis(3‐methyl‐4‐cyanatophenyl) cyclohexane, and 1,3‐dicyanato benzene, and cured with diaminodiphenylmethane as a curing agent. The reactions during the curing process between the epoxy, siloxane, and cyanate were confirmed by Fourier transform infrared analysis. The results of dynamic mechanical analysis showed that the glass‐transition temperatures of the clay‐filled hybrid epoxy systems were lower than that of neat epoxy. The data obtained from mechanical studies implied that there was a significant improvement in the strength and modulus by the nanoscale reinforcement of organomodified MMT clay with the matrix resin. The morphologies of the siloxane‐containing, hybrid epoxy/clay systems showed heterogeneous character due to the partial incompatibility of HTPDMS. The exfoliation of the organoclay was ascertained from X‐ray diffraction patterns. The increase in the percentage of organomodified MMT clay up to 5 wt % led to a significant improvement in the mechanical properties and an insignificant decrease in the glass‐transition temperature versus the unfilled‐clay systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Functionalization of carbon nanotubes with (3‐glycidyloxypropyl)‐trimethoxysilane: Effect of wrapping on epoxy matrix nanocomposites

In this work, multiwalled carbon nanotubes (MWCNT), after previous oxidation, are functionalized with excess (3‐glycidyloxypropyl)trimethoxysilane (GLYMO) and used as reinforcement in epoxy matrix nanocomposites. Infrared, Raman, and energy‐dispersive X‐ray spectroscopies confirm the silanization of the MWCNT, while transmission electron microscopy images show that oxidized nanotubes presented less entanglement than pristine and silanized MWCNT. Thickening of the nanotubes is also observed after silanization, suggesting that the MWCNT are wrapped by siloxane chains. Field‐emission scanning electron microscopy reveals that oxidized nanotubes are better dispersed in the matrix, providing nanocomposites with better mechanical properties than those reinforced with pristine and silanized MWCNT. On the other hand, the glass transition temperature of the nanocomposite with 0.05 wt % MWCNT‐GLYMO increased by 14 °C compared to the neat epoxy resin, suggesting a strong matrix–nanotube adhesion. The functionalization of nanotubes using an excess amount of silane can thus favor the formation of an organosiloxane coating on the MWCNT, preventing its dispersion and contributing to poor mechanical properties of epoxy nanocomposites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44245.     

Improved impact strength of epoxy by the addition of functionalized multiwalled carbon nanotubes and reactive diluent

Multiwalled carbon nanotubes (MWCNTs), both oxidized and amine functionalized (triethylenetetramine—TETA), have been used to improve the mechanical properties of nanocomposites based on epoxy resin. The TGA and XPS analysis allowed the evaluation of the degree of chemical modification on MWCNTs. Nanocomposites were manufactured by a three‐roll milling process with 0.1, 0.5, and 1.0 wt % of MWCNT–COOH and MWCNT–COTETA. A series of nanocomposites with 5.0 wt % of reactive diluent was also prepared. Tensile and impact tests were conducted to evaluate the effects of the nanofillers and diluent on the mechanical properties of the nanocomposites. The results showed higher gains (258% increase) in the impact strength for nanocomposites manufactured with aminated MWCNTs. Optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to investigate the overall filler distribution, the dispersion of individual nanotubes, and the interface adhesion on the nanocomposites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42587.     

Experimental assessment on potential for processiblity of carbon nanotubes/epoxy system used as nanocomposites

In this study, carboxylic acid functionalized carbon nanotubes (CNTs) were used to modify epoxy with intent to develop a nanocomposite matrix for hybrid multiscale composites combining benefits of nanoscale reinforcement with well‐established fibrous composites. CNTs were dispersed in epoxy by using high energy sonication, followed by the fabrication of epoxy/CNTs composites. The processibility of CNTs/epoxy systems was explored with respect to their dispersion state and viscosity. The dependences of viscosity, mechanical and thermomechanical properties of nanocomposite system on CNTs content were investigated. The dispersion quality and reagglomeration behavior of CNTs in epoxy and the capillary infiltration of continuous fiber with the epoxy/CNTs dispersion were characterized using optical microscope and capillary experiment. As compared with neat epoxy sample, the CNTs nanocomposites exhibit flexural strength of 126.5 MPa for 1 wt% CNTs content and impact strength of 28.9 kJ m^?2 for 0.1 wt% CNTs content, respectively. A CNTs loading of 0.1 wt% significantly improved the glass transition temperatures, T_g, of the nanocomposites. Scanning electron microscopy (SEM) was used to examine the fracture surface of the failed specimens. It is demonstrated that the properties of CNTs/epoxy system are dispersion‐dominated and interface sensitive. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Tribological characterization of graphene nanoplatelets/alumina particles filled epoxy hybrid nanocomposites

In this work, graphene nanoplatelets have been synthesized using liquid phase exfoliation of graphite flake powder. The exfoliated graphene nanoplatelets were identified and characterized by using UV–Visible–NIR spectroscopy, High resolution transmission electron microscopy, electron diffraction, scanning electron microscopy and X-ray diffraction. The obtained graphene nanoplatelets and nano alumina at various weight ratios were dispersed in an epoxy matrix to enhance the surface roughness (R_a), micro hardness (H_v) and coefficient of friction (CoF) of epoxy hybrid nanocomposites. The results showed that the R_a and CoF value for the combined loading of 0.2 wt% of graphene nanoplatelets and 0.8 wt% of alumina into the epoxy was decreased to 41.02 and 20.01% whereas, the H_v value was increased to 10.04% when compared with the neat epoxy. The improved mechanical and tribological behaviors are suitable for the applications bearing and coating.     

Enhancement of mechanical and wear resistance performance in hexagonal boron nitride‐reinforced epoxy nanocomposites

Hexagonal boron nitride (hBN), a two‐dimensional nanofiller with good mechanical properties, high thermal conductivity and excellent lubrication properties, has the potential to substantially reinforce polymers to form nanocomposites with advanced properties. In this study, we successfully prepared hBN nanosheets with a thickness of a few atoms by using amine‐capped aniline trimer (AT) as dispersant. Epoxy/hBN nanocomposites were prepared by curing reaction of epoxy E51, Jeffamine D230 and AT‐modified hBN nanosheets, where the hBN contents were 0.5, 1, 2 and 4 wt%. An increase in contact angle of the epoxy/hBN nanocomposites was evident in the presence of hBN nanosheets, implying an increase in the hydrophobic nature of the composites. The as‐prepared composites exhibited enhanced mechanical and tribological performance compared to pure epoxy resin. This effectiveness in improving the mechanical, friction and wear behavior of the epoxy composites could be attributed to the complementary action of excellent mechanical properties, lubrication and thermal conductivity of hBN nanofillers. © 2016 Society of Chemical Industry     

Poly(ester‐amine) hyperbranched polymer as toughening and co‐curing agent for epoxy/clay nanocomposites

The marriage between hardness and flexibility of epoxy resins (improved toughness) is a desired feature, which broads their application in various industrial fields, especially for high impact resistance purposes. Accordingly, this work aims to improve toughness properties of epoxy resin (Epon‐828)/Ancamine (curing agent) system using amino‐terminated hyperbranched poly(ester‐amine) [Poly(PEODA‐NPA)] (HP) as toughening and/or co‐curing agent, in presence of organo‐modified Montmorillonite clay (OMMT) as a reinforcing filler. HP was synthesized via Michael addition reaction of poly(ethylene glycol) diacrylate (PEODA) to N‐methyl‐1,3‐propanediamine (NPA). Chemical structure and molecular weight of HP were elucidated using infrared (FTIR) spectroscopy and gel permeation chromatography (GPC) techniques, respectively. Epoxy/OMMT nanocomposites toughened with HP (at different concentrations) showed remarkable improvement in their toughness without any adverse effect on the other physico‐mechanical properties. The optimum concentration of HP and OMMT was found to be 20 wt % and 1–3 wt% of the epoxy resin, respectively. The extent of exfoliation and dispersion of OMMT platelets within the epoxy cured films was assessed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. In addition, thermal gravimetric analyses (TGA‐DTA) of epoxy/OMMT nanocomposites toughened with HP showed a slight increase in their decomposition temperature, particularly at low OMMT loading. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Morphology,thermal, and mechanical properties of polyamide 66/clay nanocomposites with epoxy‐modified organoclay

A new kind of organophilic clay, cotreated by methyl tallow bis‐2‐hydroxyethyl quaternary ammonium and epoxy resin into sodium montmorillonite (to form a strong interaction with polyamide 66 matrix), was prepared and used in preparing PA66/clay nanocomposites (PA66CN) via melt‐compounding method. Three different types of organic clays, CL30B–E00, CL30B–E12, and CL30B–E23, were used to study the effect of epoxy resin in PA66CN. The morphological, mechanical, and thermal properties have been studied using X‐ray diffraction, transmission electron microscopy (TEM), mechanical, and thermal analysis, respectively. TEM analysis of the nanocomposites shows that most of the silicate layers were exfoliated to individual layers and to some thin stacks containing a few layers. PA66CX–E00 and PA66CX–E12 had nearly exfoliated structures in agreement with the SAXS results, while PA66CX–E23 shows a coexistence of intercalated and exfoliated structures. The storage modulus of PA66 nanocomposites was higher than that of the neat PA66 in the whole range of tested temperature. On the other hand, the magnitude of the loss tangent peak in α‐ or β‐transition region decreased gradually with the increase in the clay loading. Multiple melting behavior in PA66 was also observed. Thermal stability more or less decreased with an increasing inorganic content. Young's modulus and tensile strength were enhanced by introducing organoclay. Among the three types of nanocomposites prepared, PA66CX–E12 showed the highest improvement in properties, while PA66CX–E23 showed properties inferior to that of PA66CX–E00 without epoxy resin. In conclusion, an optimum amount of epoxy resin is required to form the strong interaction with the amide group of PA66. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1711–1722, 2006     

Simultaneous improvement in strength,toughness, and thermal stability of epoxy/halloysite nanotubes composites by interfacial modification

This work investigated the effect of silane modification of halloysite nanotubes (HNTs) on the mechanical properties of epoxy/HNTs nanocomposites. Three kinds of silane coupling agents, including 3‐(2‐aminoethyl)‐aminopropyltrimethoxysilane (AEAPS), (3‐glycidyloxypropyl)‐trimethoxysilane (GPTMS), and octyltriethoxysilane (OTES), were employed. It was shown that the modified HNTs exhibited a better dispersion in the epoxy matrix compared with pristine one. Because of strong interfacial interaction between AEAPS modified HNTs and the epoxy matrix, the nanocomposites exhibited the highest glass transition temperature and modulus among all the samples. On the other hand, AEAPS and GPTMS modified HNTs/epoxy nanocomposites showed enhanced tensile strength and toughness. The toughing mechanisms were identified by the SEM micrographs of the fracture surfaces of the different kinds of samples. In this study, simultaneous enhancement of strength, toughness, and thermal stability of epoxy by the modified HNTs provides a novel approach to produce high‐performance thermosets. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43249.