Epoxy-montmorillonite clay nanocomposites: Synthesis and characterization (original) (raw)
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Synthesis and characterization of new nanocomposites based on epoxy resins and organophilic clays
Polymer International, 2007
Epoxy-clay nanocomposites were synthesized using different types of modified montmorillonite, either with a classic quaternary ammonium salt or with protonated adducts synthesized by reacting resorcinol diglycidyl ether with monoamines (benzylamine or cyclohexylamine). The chemical structure was investigated using Fourier transform infrared and 1 H NMR spectrometry. The nanocomposite structures were confirmed using X-ray diffraction analysis and transmission electron microscopy. The influence of the montmorillonite modifier on the glass transition temperature of the cured composites was studied using dynamic mechanical analysis.
Intercalation of epoxy resin in organically modified montmorillonite
Journal of Applied Polymer Science, 2006
Various methods of preparation of epoxy resin/clay mixtures, before the addition of the crosslinking agent and curing to form epoxy-based polymer layered silicate (PLS) nanocomposites, have been investigated to determine their effect on the nanostructure. Organically modified montmorillonite clay was used, and the mixtures were prepared by both simple mixing and solvent-based methods. X-ray diffraction shows that intercalation of the resin into the clay galleries occurs for all clay loadings up to 25 wt % and for both preparation methods, but the dispersion of the clay in the resin, observed by optical microscopy, is significantly better for the solvent preparation method. Differential scanning calorimetry (DSC) shows that the intercalated resin has the same molecular mobility as the extra-gallery resin, but suggests that the intercalated resin does not penetrate completely into the galleries. Pro-longed storage of the resin/clay mixtures at room temperature leads to changes in the DSC response, as well as in the response to thermogravimetry, which are interpreted as resulting from homopolymerization of the epoxy resin, catalyzed by the onium ion in the modified clay. This confirms and explains the earlier observation of Benson Tolle and Anderson (J Appl Polym Sci 2004, 91, 89) that ''conditioning'' of the resin/clay mixtures at ambient temperature has a significant effect when the crosslinking agent is subsequently added, and indicates that the preparation method has important consequences for the nanostructure development in the PLS nanocomposites.
International Journal of Plastics Technology, 2011
Organic-inorganic hybrids involving organo-modified montmorillonite (OMMT) clay and tetraglycidyl diamino diphenyl methane epoxy (TGDDM) were prepared via in situ polymerization by the homogeneous dispersion of various percentages (1-5% w/w) of clay in epoxy matrix resin. The resulting homogeneous epoxy-clay hybrids were modified with 10 wt% of hydroxyl terminated polydiemthyl siloxane (HTPDMS) using γ-aminopropyltriethoxysilane (γ-APS) as coupling agent in the presence of tin catalyst. The siliconized epoxy-clay prepolymers were further modified separately with 15 wt% of bismaleimide (BMI) monomers and cured with diaminodiphenylmethane. The reactions involved during the curing process between epoxy resin, siloxane and BMI were confirmed by using FTIR and DSC curing analysis. The differential scanning calorimetry (DSC) show that the significant increase in glass transition temperatures in the clay filled hybrid epoxy systems than that of neat epoxy resin. The data obtained from thermal studies indicates that the appreciable improvement in hybrid systems was due to the incorporation of MMT clay, BMI and siloxane into epoxy systems. Scanning electron microscopy (SEM) of the hybrid systems show that the homogenous morphology. X-ray diffraction analysis of the clay hybrid systems shows that the amorphous diffraction patterns and the peaks are broadened and nearly disappeared after 24 h swelling, suggesting the formation of exfoliated structure.
2014
Three different protocols for the preparation of polymer layered silicate nanocomposites based upon a tri-functional epoxy resin, triglycidyl para-amino phenol (TGAP), have been compared in respect of the cure kinetics, the nanostructure and their mechanical properties. The three preparation procedures involve 2 wt% and 5 wt% of organically modified montmorillonite (MMT), and are: isothermal cure at selected temperatures; pre-conditioning of the resin-clay mixture before isothermal cure; incorporation of an initiator of cationic homopolymerisation, a boron tri-fluoride methyl amine complex, BF 3 •MEA, within the clay galleries. It was found that features of the cure kinetics and of the nanostructure correlate with the measured impact strength of the cured nanocomposites, which increases as the degree of exfoliation of the MMT is improved. The best protocol for toughening the TGAP/MMT nanocomposites is by the incorporation of 1 wt% BF 3 •MEA into the clay galleries of nanocomposites containing 2 wt% MMT.
Clay-Epoxy Nanocomposites: Processing and Properties
JOM Journal of the Minerals, Metals and …, 2007
The work described in this paper is focused on evaluating the effect of the processing method and nanoclay (montmorillonite) content on the ten-sile, compressive, and impact proper-ties of clay-epoxy nanocomposites. Nanocomposites are synthesized by two methods: ...
New method for the synthesis of clay/epoxy nanocomposites
Journal of Applied Polymer Science, 2006
A new liquid-liquid method for the synthesis of epoxy nanocomposites was developed. This new method improved the dispersion and exfoliation of the organoclay in the polymer matrix, thus improving the end-use properties. The microstructure and physical properties of the clay/epoxy nanocomposite synthesized by the new method were studied. Rheological tests of the uncured epoxy-organoclay system demonstrated that this method resulted in a great increase in viscosity, much more than the most commonly used direct-mixing method. The Krieger-Dougherty model successfully described the dispersion of the clay layers in the uncured epoxy. In the 5 wt % organoclay nanocomposite, compressive tests on the cured samples showed that there was a 45% increase in the maximum strength, a 10% increase in the yield strength, and a 26% increase in the modulus over the pure epoxy-amine cured system.
Bio-based epoxy clay nanocomposites
The present research focuses on the development of a new family of bio-epoxy clay nanocomposite for coatings and other high performance applications and describes the degree of clay dispersion, curing kinetics, and mechanical properties associated with these formulations. The epoxy matrix consisted of a commercial sorbitol glycidyl ether (SGE) epoxy resin cured with one of three polyaminestwo polyetheramines (one based on poly(ethylene oxide), PEO, the other based on poly(propylene oxide), PPO), and one aliphatic polyamine (triethylenetetraamine, TETA)and reinforced with organically modified montmorillonite (OMMT) nanoclay. The degree of OMMT dispersion was assessed via x-ray diffraction (XRD). The SGE/PEO and SGE/TETA systems gave shorter gel times compared to the SGE/PPO system as observed by viscosity measurements, consistent with relative differences in amine hydrogen equivalent weight. Epoxy conversion was followed via near-IR (NIR) spectroscopy. The addition of OMMT to the SGE/TETA system gave a larger increase in mechanical properties compared to the other epoxy formulations. Based on the results of these evaluations, it is concluded that SGE/polyamine systems show promise as aliphatic epoxy nanocomposite networks for green coatings and high performance applications.
Properties of Epoxy Systems with Clay Nanocomposites
Mechanics of Composite Materials, 2003
Different types of montmorillonite clays are often used for the modification of thermoplastic polymers. In the case of epoxy systems, the presence of the clays can complicate the cure process. Therefore, the influence of montmorillonite concentration and the temperature regime on the cure rate and mechanical properties of the composite material obtained is investigated in this paper.
Characterization of Natural and Modified Clays to the Development of Polymeric Nanocomposites
Macromolecular Symposia, 2011
Bentonite is a technical term applied to layered silicates of very thin granulation, mainly composed by minerals of the smectites group. Montmorillonite, a phylossilicate with layers as thick as 1 nm, is the most common structure in the bentonite clay. The polarity of these materials is incompatible with most of the usual polymers and in order to overcome this problem, chemical modifications are often necessary. The purpose of this work is to evaluate the chemical and physical characteristics of different bentonites by comparing their product data sheets, their performance in the water Foster swelling and their response to chemical modifications of their surfaces structures. The samples were characterized by infrared spectroscopy and X-ray diffraction analysis. All bentonite samples showed effective intercalations of the modifying agent on their surface structures. This behavior showed the possibility of usage of these materials in the polymer layered silicates nanocomposites preparations.
Composites Science and Technology, 2011
This paper investigates the effect of both the mixing technique and heating rate during cure on the dispersion of montmorillonite (MMT) clay in an epoxy resin. The combination of sonication and using a 10 °C/min heating rate during cure was found to facilitate the dispersion of nanoclay in epoxy resin. These processing conditions provided a synergistic effect, making it possible for polymer chains to penetrate in-between clay galleries and detach platelets from their agglomerates. As the degree of dispersion was enhanced, the flexural modulus and strength properties were found to decrease by 15% and 40%, respectively. This is thought to be due to individual platelets fracturing in the nanocomposite. Complementary techniques including X-ray diffraction (XRD), small angle X-ray scattering (SAXS), scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX), transmission electron microscopy (TEM) and optical microscopy were essential to fully characterise localised and spatial regions of the clay morphologies.► Effect of mixing method and heating rate on dispersion of MMT in epoxy investigated. ► Sonication and a 10 °C/min heating rate facilitated the dispersion of MMT in epoxy. ► As the degree of dispersion was enhanced, the flexural properties decreased. ► XRD, SAXS, SEM–EDX, TEM and optical microscopy fully characterised clay morphologies.