Mesua ferrea L. seed oil based highly branched polyester/epoxy blends and their nanocomposites

Mesua ferrea L. seed oil based highly branched polyester and epoxy resins blends were prepared by mechanical mixing at different weight ratios. The best performing blend was used as the matrix for the preparation of nanocomposites with different dose levels of organophilic montmorillonite (OMMT) nanoclay. The prepared nanocomposites were characterized by X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. Data resulting from the mechanical and thermal studies of the blends and nanocomposites indicated improvements in the tensile strength and thermal stability to appreciable extents for the nanocomposites with OMMT loading. The nanocomposites were characterized as well‐dispersed, partially exfoliated structures with good interfacial interactions. From the X‐ray diffraction analysis, the absence of d₀₀₁ reflections of the OMMT clay in the cured nanocomposites indicated the development of an exfoliated clay structure, which was confirmed by transmission electron microscopy. The homogeneous morphologies of the pure polyester/epoxy blend and clay hybrid systems were ascertained with scanning electron microscopy. The tensile strength of the 5 wt % clay‐filled blend nanocomposite system was increased by 2.4 times compared to that of the pure blend resin system. The results suggest that the prepared nanocomposites have the potential to be used as active thin films for different applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of Nanoclay on the Mechanical,Thermal, and Water Absorption Properties of an UP-toughened Epoxy Network

Unsaturated polyester (UP)-toughened epoxy nanocomposites were prepared, and their effective mechanical and thermal properties were studied. Two types of organo-modified montmorillonite (OMMT) clays were used to prepare the nanocomposites. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis showed the formation of exfoliated silicate layers in the UP-toughened epoxy matrix. Mechanical tests revealed that nanocomposites (containing 1 wt% OMMT clay) showed an increase in tensile strength to 13.8%, flexural strength to 10%, and impact strength to 4% compared with an UP-toughened epoxy blend. The effect of different heating rates on the curing behavior of UP-toughened epoxy nanocomposites was investigated using non-isothermal differential scanning calorimetry. The data were interpreted using the Kissinger and Flynn–Wall–Ozawa models to find the curing reaction parameter. The water uptake behavior for nanocomposites increased with the addition of OMMTs. Scanning electron microscopy micrographs indicated morphological changes in the impact fractured samples of UP-toughened epoxy nanocomposites.     

Thermally-cured and e-beam-cured epoxy layered-Silicate nanocomposites

Summary Research on nanocomposites attracted a lot of attention because of their unique nanostructure and interesting properties. Layered-Silicate epoxy nanocomposites cured by traditional thermal cure processing were prepared, and the morphology was confirmed by the wide-angle x-ray diffraction, small-angle x-ray scattering and transmission electron microscopy. Layered-Silicate epoxy nanocomposites could also be cured through e-beam curing. The small-angle x-ray scattering and transmission electron microscopy indicated that the e-beam-cured nanocomposites showed intercalated nanostructure. Dynamic mechanical analysis showed some improvement of the Storage modulus for the nanocomposites with high T_g. Received 11 October 2002/Revised Version 22 January 2003/ Accepted 23 January 2003 Correspondence to Chenggang Chen     

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     

Modification of carbon nanotubes and its effect on properties of carbon nanotube/epoxy nanocomposites

We have studied an effect of three types of modifications of carbon nanotubes (CNTs) on dispersion and mechanical properties of final epoxy‐amine based nanocomposites. First approach includes end‐walled covalent chemical modification at the ends of nanotubes. The second one is side‐walled covalent chemical modification along the whole length of nanotubes. The third procedure is noncovalent, physical modification done by the CNT surface coating with polyaniline. The modification of nanotubes was determined by X‐ray photoelectron spectroscopy. The prepared epoxy‐amine nanocomposites were characterized by dynamic‐mechanical analysis, tensile testing, light microscopy, transmission electron microscopy, and thermogravimetry. We observed an improvement of the mechanical properties and the thermal stability by addition of the carbon nanotubes to the epoxy matrix. The strong interactions between the nanotube and the polymer matrix were discovered in the nanocomposites with physically modified nanotubes. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Amino functionalization of multiwalled carbon nanotubes by gamma ray irradiation and its epoxy composites

In this paper, γ‐ray radiation technique was utilized to simply functionalize multi‐walled carbon nanotube (MWCNT) with amino groups. The successful amino functionalization of MWCNTs (MWCNTs‐Am) was proven and the physicochemical properties of MWCNTs before and after radiation grafting modifications were characterized using FT‐IR, X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results indicated that the γ‐ray radiation had the visible effects on the surface properties of MWCNTs. The effects of various functionalized MWCNTs on morphological, thermal, and mechanical properties of an epoxy‐based nanocomposite system were investigated. Utilizing in situ polymerization, 1 wt% loading of MWCNT was used to prepare epoxy‐based nanocomposites. Compared to the neat epoxy system, nanocomposites prepared with MWCNT‐Am showed 13.0% increase in tensile strength, 20.0% increase in tensile modulus, and 24.1% increase in thermal decomposition temperature. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Preparation and properties of TiO2‐filled poly(acrylonitrile‐butadiene‐styrene)/epoxy hybrid composites

Poly (acrylonitrile‐butadiene‐styrene) (ABS) was used to modify diglycidyl ether of bisphenol‐A type of epoxy resin, and the modified epoxy resin was used as the matrix for making TiO₂ reinforced nanocomposites and were cured with diaminodiphenyl sulfone for superior mechanical and thermal properties. The hybrid nanocomposites were characterized by using thermogravimetric analyzer (TGA), dynamic mechanical analyzer (DMA), universal testing machine (UTM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The bulk morphology was carefully analyzed by SEM and TEM and was supported by other techniques. DMA studies revealed that the DDS‐cured epoxy/ABS/TiO₂ hybrid composites systems have two T_gs corresponding to epoxy and ABS rich phases and have better load bearing capacity with the addition of TiO₂ particles. The addition of TiO₂ induces a significant increase in tensile properties, impact strength, and fracture toughness with respect to neat blend matrix. Tensile toughness reveals a twofold increase with the addition of 0.7 wt % TiO₂ filler in the blend matrix with respect to neat blend. SEM micrographs of fractured surfaces establish a synergetic effect of both ABS and TiO₂ components in the epoxy matrix. The phenomenon such us cavitation, crack path deflection, crack pinning, ductile tearing of the thermoplastic, and local plastic deformation of the matrix with some minor agglomerates of TiO₂ are observed. However, between these agglomerates, the particles are separated well and are distributed homogeneously within the polymer matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effects of Nickel Oxide (NiO) nanoparticles on the performance characteristics of the jatropha oil based alkyd and epoxy blends

Plant oil based alkyd resin was prepared from jatropha oil and blended with epoxy resin. Subsequently, alkyd/epoxy/NiO nanocomposites with different wt % of NiO nanoparticles have been prepared by mechanical mixing of the designed components. The structure, morphology, and performance characteristics of the nanocomposites were studied by UV‐visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and universal testing machine (UTM). The alkyd/epoxy/NiO nanocomposites showed the gradual increase in thermal stability with increasing NiO content. With 3 wt % NiO content the tensile strength of the nanocomposite increased by 19 MPa (more than twofold) when compared with the pristine polymer. Limiting oxygen index (LOI) value of the nanocomposites indicate that the incorporation of NiO nanoparticles even in 1 wt % can greatly improves the flame retardant property of the nanocomposites. This study confirms the strong influence of NiO nanoparticles on the thermal, mechanical, and flame retardant properties of the alkyd/epoxy/NiO nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41490.     

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     

The structure‐property relationship of novolac cured epoxy resin/clay nanocomposites

Intercalated or exfoliated novolac cured epoxy resin nanocomposites were prepared with two different kinds of layered silicates – montmorillonite (PK‐802) and nontronite (PK‐805). The bifunctional modifiers (PI/BEN or MI/BEN) are used to modify the clays for improvement of the properties of polymer where benzalkonium chloride (BEN) acts as a compatibilizing agent and 2‐phenylimidazole (PI) or 2‐methylimidazole (MI) as the accelerators. Both the compatibilizer and accelerator are simultaneously intercalated into the gallery space of pure clays to form the modified clay. The novolac cured epoxy nanocomposites are prepared with these modified clays by crosslinking polymerization reaction. The properties of novolac cured epoxy/clay nanocomposites were characterized by wide‐angle X‐ray diffraction (WAXD), thermo‐gravimetric analysis (TGA), dynamic mechanical analysis (DMA), and transmission electron microscopy (TEM) methods. According to the measurement, these novolac cured epoxy‐clay nanocomposites have been shown the significant improvement in the thermal, mechanical, and barrier properties that may be applied to make printed circuit board. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Natural inorganic nanotubes reinforced epoxy resin nanocomposites

Natural occurred nanotubes, halloysite nanotubes, were modified by silane and incorporated into epoxy resin to form nanocomposites. The morphology of the nanocomposites was characterized by transmission electron microscopy (TEM). Dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were performed on the nanocomposites. Flexural property and coefficient of thermal expansion (CTE) of the nanocomposites were also determined. Comparing with the neat resin, about 40% increase in storage modulus at glassy state and 133% at rubbery state were achieved by incorporating 12 wt% modified HNTs into the epoxy matrix. In addition, the nanocomposites exhibited improved flexural strength, char yield and dimensional stability. TEM examination revealed a uniform dispersion of the nanotubes in the epoxy resin. The remarkably positive effects of the HNTs on the performance of the epoxy resin were correlated with the unique characteristics of the HNTs, the uniform dispersion and the possible interfacial reactions between the modified HNTs and the matrix.     

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     

Development and characterization of surface-modified mullite reinforced BMI-toughened epoxy nanocomposites

High-performance diglycidyl ether of bisphenol-A (DGEBA) epoxy-based composite systems with improved thermal stability for advanced structural applications were developed, using bismaleimide (BMI) as toughening agent and surface-modified mullite as reinforcing agent. The nanocomposites developed in the present study are referred to as M/DGEBA–BMI. 95 % by wt. of DGEBA was toughened with 5 % by wt. of BMI and further reinforced with varying weight percentages of (0.5, 1.0 and 1.5 wt%) glycidyl-functionalized mullite to obtain M/DGEBA–BMI nanocomposites. The formation of nanocomposites was ascertained using Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The mechanical and dielectric properties of nanocomposites were investigated by analytical techniques. The thermal behaviour of nanocomposites was characterized using thermogravimetric analyzer and differential scanning calorimeter. Contact angle, surface free energy and percentage water absorption were also studied and reported. Studies suggest that the properties of M/DGEBA–BMI nanocomposites viz; mechanical, dielectric, surface energy and thermal properties improved to an appreciable extent, when compared to those of neat epoxy matrix.     

Strengthening and toughening effects of layered double hydroxide and hyperbranched polymer on epoxy resin

The effects of organically modified layered double hydroxide (O-LDH) and epoxy functionalized hyperbranched aliphatic polyester (E1), on the mechanical strength, thermal property and toughness of diglycidyl ether of bisphenol A (DGEBA) epoxy resin were studied in detail. The crystalline structure and morphology of the nanocomposites composed of DGEBA/O-LDH and DGEBA/E1/O-LDH were investigated by wide angle X-ray diffraction analysis and transmission electron microscopy observation. Both results showed that the LDH nanosheets were sufficiently exfoliated and randomly dispersed in the epoxy matrix. The thermal and mechanical properties were compared with the corresponding neat polymer matrix. The enhancement in strength and toughness was achieved by the addition of O-LDH and E1, respectively, and confirmed in terms of fracture surface analysis by scanning electron microscopy.     

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.     

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.     

Mechanical and thermal properties of novel rubber‐toughened epoxy blend prepared by in situ pre‐crosslinking

A novel method is used for preparing liquid rubber‐toughened epoxy blend, in which an initiator was added to the liquid rubber–epoxy mixture to initiate crosslinking reaction of liquid rubber, and then curing agent was added to form the thermoset. Two epoxy blends with carboxyl‐terminated butadiene‐acrylonitrile copolymers were prepared using traditional and novel methods respectively. Results indicated that the novel rubber‐toughened epoxy blend exhibited much better mechanical properties than its traditional counterpart. The morphologies of the blends were explored by transmission electron microscopy (TEM), it was revealed that the use of the novel method formed a local interpenetrating network structure in the blend, which substantially improved the interfacial adhesion. The impact fracture surfaces of the two blends were observed by scanning electron microscopy (SEM) to explore the toughening mechanism, it was found that crack pinning was the major toughening mechanism for the novel rubber‐toughened epoxy blend. Dynamic mechanical analysis (DMA) was applied to determine the T_g values of the blends, which were found to be close. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41110.     

Mechanical and morphological properties of carbon fiber reinforced–modified epoxy composites

Epoxy, prepared through aminomethyl 3,5,5‐trimethylcyclohexylamine hardening of diglycidylether of bisphenol‐A (DGEBA) prepolymer, toughened with polycarbonate (PC) in different proportions, and reinforced with carbon fiber, was investigated by differential scanning calorimetry, tensile and interlaminar shear strength testing, and scanning electron microscopy (SEM). A single glass transition temperature was found in all compositions of the epoxy/PC blend system. The tensile properties of the blend were found to be better than that of the pure epoxy matrix. They increased with PC content up to 10%, beyond which they decreased. The influence of carbon fiber orientation on the mechanical properties of the composites was studied, where the fiber content was kept constant at 68 wt %. Composites with 45° fiber orientation were found to have very weak mechanical properties, and the mechanical properties of the blend matrix composites were found to be better than those of the pure epoxy matrix composites. The fracture and surface morphologies of the composite samples were characterized by SEM. Good bonding was observed between the fiber and matrix for the blend matrix composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3529–3536, 2006     

Effect of bone ash fillers on mechanical and thermal properties of biobased epoxy nanocomposites

In this study, the fabrication and characterization of bone ash filled biobased epoxy resin (Super SAP 100/1000, contains 37% biobased carbon content) nanocomposites are presented. Biosource bone ash was modified by size reduction and surface modification processes using a combination of ball milling and sonochemical techniques and characterized using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The modified bone ash particles were incorporated into biobased epoxy with noncontact mixing process. The as-fabricated nanocomposites were characterized using various thermal and mechanical analyses. The nanocomposites showed significant improvement in flexural strength (41.25%) and modulus (34.56%) for 2 wt% filler loading. Dynamic mechanical analysis (DMA) results showed improvement in both storage modulus and loss modulus. Additionally, DMA results showed a slight reduction in glass transition temperature which also complies with differential scanning calorimetry results. Thermomechanical analysis results showed a reduction in the coefficient of thermal expansion. Thermogravimetric analysis results showed improved thermal stability at both onset of degradation and the major degradation. These enhanced thermal and mechanical performances of the epoxy nanocomposites allows them to be suitable for lightweight aerospace, automotive, and biomedical applications.     

High impact strength epoxy nanocomposites with natural nanotubes

Epoxy-based nanocomposites were prepared with natural nanotubes from halloysite, a clay mineral with the empirical formula Al₂Si₂O₅(OH)₄. The morphology of the nanotubes was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and was found geometrically similar to multi-walled carbon nanotubes. The thermal and mechanical properties of the nanocomposites were characterized by thermogravimetric analysis, dynamic mechanical analysis, Charpy impact and three-point bending tests. The results demonstrated that blending epoxy with 2.3 wt% halloysite nanotubes increased the impact strength by 4 times without scarifying flexural modulus, strength and thermal stability. Unique toughening mechanisms for this improvement were investigated and discussed. It was proposed that impact energy was dissipated via the formation of damage zones with a large number of micro-cracks in front of the main crack. The micro-cracks were stabilized by nanotube bridging. Nanotube bridging, pull-out and breaking were also observed and proposed as the major energy dissipating events. The findings of this work suggest that halloysite nanotube may be an effective impact modifier for epoxy and other brittle polymers.