Dispersed Epoxy Research Articles

Reinforcement of Bisphenol-F epoxy resin composites with fluorinated carbon nanotubes

Pristine and fluorinated carbon nanotubes (CNT) were studied by FTIR, TGA, Raman spectroscopy, transmission and scanning electron microscopy. Influence of fluorination on CNT dispersion in epoxy resin was studied by the dynamic light scattering. It was shown that fluorination favoured CNT dispersion in epoxy matrix. Mechanical properties (tensile and flexural strength and modulus, abrasion resistance, thermal diffusivity and heat conductivity), thermal stability and fracture texture of epoxy resin (Bisphenol-F type) polymer composites with added unmodified and fluorinated CNT were studied. Insertion of pristine and fluorinated CNT into epoxy matrix did not influence composites thermal stability below 275 °C and resulted in a very small worsening of thermal stability over 275–375 °C range. Insertion of both pristine and fluorinated CNT into epoxy matrix resulted in composites reinforcement but fluorinated CNT were more efficient in reinforcement than pristine CNT. The best reinforcement was obtained for 0.1 wt % CNT fluorinated at 150 °C. Tensile strength and modulus were increased by 50% and 74% respectively, flexural strength and modulus were increased by 60 and 66% respectively. Obtained in the frames of the current research results on a relative reinforcement exceed data from available literature data. Insertion of both pristine and fluorinated CNT into epoxy matrix did not improve composite conductivity. Insertion of 0.5 wt % fluorinated CNT into composites resulted in +25% increase of the thermal diffusivity. Fluorinated CNT are more effective than pristine CNT. Presence of both pristine and fluorinated CNT did not influence thermal conductivity. Fluorinated CNT were more effective in abrasion decrease than pristine CNT. The best results – abrasion decrease by 33% - was obtained for the composites with 0.1 wt % fluorinated CNT.

Multiscale metrologies for process optimization of carbon nanotube polymer composites

Carbon nanotube (CNT) polymer nanocomposites are attractive multifunctional materials with a growing range of commercial applications. With the increasing demand for these materials, it is imperative to develop and validate methods for on-line quality control and process monitoring during production. In this work, a novel combination of characterization techniques is utilized, that facilitates the non-invasive assessment of CNT dispersion in epoxy produced by the scalable process of calendering. First, the structural parameters of these nanocomposites are evaluated across multiple length scales (10−10 m to 10−3 m) using scanning gallium-ion microscopy, transmission electron microscopy and small-angle neutron scattering. Then, a non-contact resonant microwave cavity perturbation (RCP) technique is employed to accurately measure the AC electrical conductivity of the nanocomposites. Quantitative correlations between the conductivity and structural parameters find the RCP measurements to be sensitive to CNT mass fraction, spatial organization and, therefore, the processing parameters. These results, and the non-contact nature and speed of RCP measurements identify this technique as being ideally suited for quality control of CNT nanocomposites in a nanomanufacturing environment. When validated by the multiscale characterization suite, RCP may be broadly applicable in the production of hybrid functional materials, such as graphene, gold nanorod, and carbon black nanocomposites.

Epoxy-acrylic core-shell particles by seeded emulsion polymerization

We developed a novel method for synthesizing epoxy-acrylic hybrid latexes. We first prepared an aqueous dispersion of high molecular weight solid epoxy prepolymers using a mechanical dispersion process at elevated temperatures, and we subsequently used the epoxy dispersion as a seed in the emulsion polymerization of acrylic monomers comprising methyl methacrylate (MMA) and methacrylic acid (MAA). Advanced analytical techniques, such as scanning transmission X-ray microscopy (STXM) and peak force tapping atomic force microscopy (PFT-AFM), have elucidated a unique core-shell morphology of the epoxy-acrylic hybrid particles. Moreover, the formation of the core-shell morphology in the seeded emulsion polymerization process is primarily attributed to kinetic trapping of the acrylic phase at the exterior of the epoxy particles. By this new method, we are able to design the epoxy and acrylic polymers in two separate steps, and we can potentially synthesize epoxy-acrylic hybrid latexes with a broad range of compositions.

Rheological and microstructural properties of foamed epoxy asphalt

Epoxy asphalt has been extensively used in the bridge deck pavement. The main concerns during the construction process of epoxy asphalt are including high construction temperature, high viscosity to deal with and limited construction time which finally affects the service performance of the pavement. In this study, foamed epoxy asphalt is proposed to solve these construction challenges. The foamed epoxy asphalt samples were prepared by foaming machine at different foaming water content in the laboratory. The viscosity-temperature performance, failure temperature, ZSV@60°C, temperature sensitivity and storage stability were evaluated by rotational viscometer, temperature sweep, frequency sweep and storage tests. Fluorescence microscope and Infrared spectroscopy were utilized to characterize the morphology and chemical reaction change of non-foamed and foamed epoxy asphalt with different foaming water content. The results show that the addition of foaming water could improve the workability of foamed epoxy asphalt binder mixtures and prolong the allowable reserved time of construction process. Compared to non-foamed epoxy asphalt, foamed epoxy asphalt compromise failure temperature and viscosity@60°C and improve the temperature sensitivity and storage stability. With the increase of foaming water content, the failure temperature, viscosity@60°C and storage stability of foamed epoxy asphalt decrease at some extent, while the temperature sensitivity of foamed epoxy asphalt increases. According to the change of microstructure, the foaming water is beneficial to enhance the epoxy resin dispersion in the asphalt and promote the chemical reaction between epoxy resins and curing agent, which could improve the pavement performance of epoxy asphalt.

Development of silane grafted ZnO core shell nanoparticles loaded diglycidyl epoxy nanocomposites film for antimicrobial applications

In this article a series of epoxy nanocomposites film were developed using amine functionalized (ZnO-APTES) core shell nanoparticles as the dispersed phase and a commercially available epoxy resin as the matrix phase. The functional group of the samples was characterized using FT-IR spectra. The most prominent peaks of epoxy resin were found in bare epoxy and in all the functionalized ZnO dispersed epoxy nanocomposites (ZnO-APTES-DGEBA). The XRD analysis of all the samples exhibits considerable shift in 2θ, intensity and d-spacing values but the best and optimum concentration is found to be 3% ZnO-APTES core shell nanoparticles loaded epoxy nanocomposites supported by FT-IR results. From TGA measurements, 100wt% residue is obtained in bare ZnO nanoparticles whereas in ZnO core shell nanoparticles grafted DGEBA residue percentages are 37, 41, 45, 46 and 52% for 0, 1, 3, 5 and 7% ZnO-APTES-DGEBA respectively, which is confirmed with ICP-OES analysis. From antimicrobial activity test, it was notable that antimicrobial activity of 7% ZnO-APTES core shell nanoparticles loaded epoxy nanocomposite film has best inhibition zone effect against all pathogens under study.

Electrochemical and anticorrosion behaviors of hybrid functionalized graphite nano-platelets/tripolyphosphate in epoxy-coated carbon steel

Functionalized graphite nano-platelets (FGNP) were combined with tripolyphosphate (TPP) to gain a hybrid nano-particle (FGNP-TPP) with homogenous dispersion in epoxy, resulting in an excellent anti-corrosion coating for carbon steel substrate. Characterization analyses of the hybrid nano-particle were performed by FT-IR, SEM, XRD and TEM. TPP was linked to FGNP nano-particles by hydrogen bondings. Different epoxy coatings formulated with 1wt.% of FGNP, FGNP-TPP and TPP were evaluated. Electrochemical investigations, salt spray and pull-off tests showed that the hybrid nano-particle can provide long-term corrosion protection compared to FGNP and TPP due to synergistic effect between FGNP as an accelerator and TPP as a corrosion inhibitor to produce a uniform and stable iron-phosphate passive film with high surface coverage.

An approach to identify complex CNT reinforcement effect on the interlaminar shear strength of prepreg composites by Taguchi method

Several factors affect the interlaminar shear strength of carbon nanotube reinforced carbon fiber composites in multi-scale. A combined route of CNT toughening through manufacturing a custom made prepreg system with CNT dispersion in epoxy and integrating vertically aligned CNTs as nanofibers to bridge in between prepreg plies is applied to achieve enhanced interlaminar shear strength (ILSS). Depending on the CNT loading, effectiveness of dispersion and CNT bridging between prepreg plies, the mechanical enhancement is achieved up to 15%. A new approach of identifying the critical parameters of nano-engineered and nano-reinforced composites through Taguchi method is a novel route for investigating the combined effects of several factors in a complex mechanical enhancement problem with reduced number of experiments as studied in here. Taguchi L8 orthogonal array is used to obtain maximum ILSS by short beam shear (SBS) test. The parametric study has shown that the most significant parameters affecting the ILSS results are type of epoxy, fabrication procedure and CNT loading.

High yield synthesis of amine functionalized graphene oxide and its surface properties

High yield amination of GO showing improved dispersion in epoxy resin.

Conducting poly(o-anisidine) nanofibre dispersed epoxy-siloxane composite coatings: synthesis, characterization and corrosion protective performance

Tartaric acid–dodecylbenzenesulphonic acid doped poly(o-anisidine) dispersed epoxy–siloxane nanocomposites exhibited promising application as new generation smart anti-corrosive coating materials.

Nanoindentation, compression and fractural characterization of highly dispersed epoxy silica nanocomposites

Uniaxial compression tests were conducted in this study in order to investigate the compressive properties of the unmodified and nanomodified epoxy with silica nanoparticles. An instrumented nanoindentation technique was also used to investigate its applicability for measuring mechanical properties for such nanocomposite systems. Additionally, the fracture toughness of the unmodified and nanomodified epoxy was measured with single-edge-notch bending tests. The Young’s modulus was found to significantly improve with addition of silica nanoparticles and increase with increasing filler content when measured with both compression and nanoindentation tests. The modulus obtained from the nanoindentation testing was 4–8% higher than the one obtained from the compression tests. As expected, the addition of silica nanoparticles had a significant impact on the fracture toughness and fracture energy and increased with increasing filler content, while observation of the fracture surfaces using SEM suggested that the nanoparticles affected the fracture behavior of such epoxy systems. Implementation of an analytical model in the current nanomodified epoxy network as compared with the experimental fracture energy results showed that the 15% matrix void growth, from debonded nanoparticles, as well as the matrix shear banding are the governing mechanisms of energy absorption.

Phase Inversion Emulsification and Enhancement of Physical Properties for Cationic Emulsified Asphalt

In this work, the emulsified asphalt with high phase stability and storage stability was prepared by using phase inversion emulsification and the surfactant mixed with cationic and nonionic surfactants. It was found that the asphalt together with Span 20, nonionic surfactant and DDA (Dimethyl Dodecyl Amine), cationic surfactant showed the most stable phase. The phase stability of the emulsified asphalt, therefore, was investigated through the particle size with mixed surfactant content, rheology behavior and Zeta potential value; the particle size decreased with the increase of the mixed surfactant content but the viscosity increased. The shear thinning behaviors and the Zeta potential value with 50 mV~60 mV were shown, which was found to be considered stable. In addition, SBR latex(Styrene-butadiene-rubber) and water dispersed Epoxy (EPD) were used to enhance the physical properties of the emulsified asphalt. The swelling and adhesion features of the emulsified asphalt were also studied with <TEX>$CaCO_3$</TEX>, Silica, and Montmorillonite (MMT). It was shown that the addition of SBR latex and MMT can be another way to improve the physical properties of the emulsified asphalt in that the lowest swelling feature was found.

Preparation and Characterization of Anionic Emulsified Asphalt with Enhanced Adhesion Properties

In this study, the anionic emulsified asphalt was prepared by dispersing asphalt particles evenly into water with combination of anionic and nonionic surfactants. Effects of NaOH and <TEX>$CaCl_2$</TEX> on the phase stability of the emulsified asphalt were also investigated through zeta potential value and rheology behavior; the emulsified asphalt added with NaOH and <TEX>$CaCl_2$</TEX> showed higher zeta potential value than that the asphalt with addition of only anionic and nonionic surfactants. In addition, with regard to shear thinning behaviors, it was found that pH of the emulsified anionic asphalt and <TEX>$Ca^{2+}$</TEX>, counter ion, affected the phase stability. SBR (styrene-butadiene-rubber) latex, EPD (water dispersed Epoxy), PU (polyurethane) and RI-10S, SBS (styrene-butadiene-styrene)-based property improvement additive, were used and studied to enhance the adhesion properties with the aggregates. RI-10S, however, was found to be only compatible with the anionic emulsified asphalt; the coating rate, adhesion and compression strength were increased with the RI-10S content.

Mechanical property characterization of carbon nanofiber/epoxy nanocomposites reinforced by GMA-grafted UHMWPE fibers

Carbon nanofibers (CNFs) dispersed epoxy resin was reinforced with unidirectional glycidyl methacrylate (GMA) grafted ultra-high molecular weight polyethylene (UHMWPE) fibers. Tensile tests were performed on unfilled, and CNF filled epoxy to identify the effect of adding CNFs on the mechanical properties of epoxy. The highest improvement in strength was obtained with 1 wt% of CNF. Tensile and flexural properties improvements in three-component nanocomposites were confirmed by obtained results. The combined use of CNFs and GMA-grafted UHMWPE fibers leads to a significant synergy in the mechanical properties of nanocomposites. The mechanisms of such synergism were analyzed by fracture studies using scanning electron microscopy.

Fracture Behaviors of TRGO-Filled Epoxy Nanocomposites with Different Dispersion/Interface Levels

In this work, we investigate mechanical properties and fracture behaviors of thermally reduced graphene oxide (TRGO)-filled epoxy composites with two different dispersion/interface levels. The amphiphilic surfactant treatment of TRGO was found to promote the dispersion in both water and epoxy, but also produced improved TRGO/epoxy interface. As expected, incorporation of untreated or treated TRGO sheets into epoxy increases the storage modulus and the glass transition temperature. In particular, significant improvements in both tensile strength and fracture toughness (KIC) of the TRGO/epoxy composites were also obtained after the surfactant treatment processing. For example, at a very low loading of 0.20 wt.-%, the surfactant-treated TRGO enhances the tensile strength and KIC of epoxy by ∼51 and∼65%, respectively; while the corresponding untreated TRGO results in almost unchanged strength and produces ∼52% improvement in the KIC value. Based on the fractography observation and analysis, several failure mechanisms, e.g., crack bridging, pull-out/debonding, and fracture of TRGO as well as matrix plastic deformation, were identified and correlated to the increased fracture toughness of the two composite systems studied.

Improvement in Dispersion of Phosphate Pigments Modified by Functionalized Graphite Nanoplatelets and Its Influence on Epoxy Coating Adhesion

Tripolyphosphate corrosion inhibitor was modified by functionalized graphite nanoplatelets to obtain a hybrid nanoparticle (functionalized graphite nanoplatelets–tripolyphosphate) with homogenous dispersion in epoxy coating. The effect of functionalized graphite nanoplatelets–tripolyphosphate dispersion on adhesion and anticorrosion behavior was discussed. Characterization analyses of the hybrid nanoparticle were performed by Fourier transform-infrared spectroscope, scanning electron microscope, and transmission electron microscope. Tripolyphosphate was linked to functionalized graphite nanoparticles by hydrogen bondings. Different epoxy coatings formulated with 1 wt% of functionalized graphite nanoplatelets, functionalized graphite nanoplatelets–tripolyphosphate, and tripolyphosphate were evaluated. Results showed, compared to traditional phosphate pigments, the adhesion of functionalized graphite nanoplatelets–tripolyphosphate epoxy coating and its anticorrosion behavior were significantly increased with the lowest loadings amounts.

Conducting poly(o-anisidine-co-o-phenyldiammine) nanorod dispersed epoxy composite coatings: synthesis, characterization and corrosion protective performance

Conducting polymers (CPs) have been significantly contributing to the development of high performance new-generation anti-corrosive coatings.

Energy absorption capability of carbon nanotubes dispersed in resins under compressive high strain rate loading

The focus of the present study is on energy absorption capability (EA) of carbon nanotubes (CNTs) dispersed in thermoset epoxy resin under compressive high strain rate loading. Toward this objective, high strain rate compressive behavior of multi-walled carbon nanotube (MWCNT) dispersed epoxy is investigated using a split Hopkinson pressure bar. The amount of MWCNT dispersion is varied up to 3% by weight. Calculation methodology for the evaluation of EA of individual CNTs and CNTs dispersed in resins/composites is presented. Quantitative data on EA of individual CNTs and CNTs dispersed in resins under quasi-static and high strain rate loading is given.

Mechanical properties of hybrid structural composites reinforced with nanosilica

Epoxy‐based hybrid structural composites reinforced with 14 nm spherical silica particles were investigated for mechanical properties as a function of nanosilica loading fractions. Composites were fabricated using continuous glass or carbon fiber of unidirectional architecture and nanosilica dispersed epoxy, through resin film infusion process. Uniform dispersion of nanoparticles in resin matrix was ensured by an optimized ultrasound‐assisted process. Although resin viscosity marginally reduces in the presence of nanosilica enabling a better control in composite manufacturing process, glass transition temperature of epoxy remained unaffected at low weight fractions. Compressive strength of hybrid glass or carbon fiber/epoxy composites showed more than 30–35% increase with nanosilica at a concentration as low as 0.2 wt%. Tensile and compressive properties of hybrid composites in transverse direction to the reinforcement remained unaffected. POLYM. COMPOS. 37:1216–1222, 2016. © 2014 Society of Plastics Engineers

Analytical and experimental studies on ballistic impact behavior of carbon nanotube dispersed resin

An analytical formulation is presented for the prediction of ballistic impact behavior of multi-walled carbon nanotube (MWCNT) dispersed epoxy resin. The formulation is based on stress wave propagation and energy balance between the projectile and the target. During the ballistic impact event, the energy lost by the projectile is absorbed by the target through various damage and energy absorbing mechanisms such as compression of the target directly below the projectile, compression in the region surrounding the impacted zone, shear plugging, formation of ring and radial cracks in the resin leading to tensile failure and energy absorbed due to the presence of carbon nanotubes. Complete failure of the target was due to catastrophic brittle fracture and shattering. Experimental studies are carried out on ballistic impact behavior of neat epoxy and MWCNT dispersed epoxy. Typical results on ballistic limit velocity and energy absorbed by various mechanisms are presented. Ballistic impact behavior of neat epoxy resin and MWCNT dispersed epoxy resin are compared. A good match is observed between the analytical and experimental results.

Synthesis and properties of nanohybrid materials with SiO2 and epoxy resin.

SiO2-epoxy nanohybrid materials were synthesized by hybridization of surface-modified colloidal silica nanoparticle (CS) and epoxy resin. The CS was surface-modified with either methyltrimethoxysilane (MTMS) or phenyltrimethoxysilane (PTMS) followed by the solvent exchange with dimethylacetamide (DMAc) to have a homogenous dispersion in epoxy resin. Various amounts of surface-modified CS were mixed with epoxy resin. The chemical structures of surface-modified CS were investigated with FT-IR spectroscopy. The particle sizes of CS and surface-modified CS were measured with DLS. The morphology of hybrid materials analyzed using FE-SEM and AFM showed homogeneous dispersion in epoxy resin. The optical and thermal properties of the hybrid materials determined by refractive index meter and DSC were lower in RI and higher in Tg than neat epoxy resin, respectively.