Cloisite 20A Research Articles

Rapid preparation of epoxy acrylate-clay nanocomposite: Simultaneous acrylation/nanoclay dispersion under ultrasonication

Abstract The main theme of the present study was to prepare the epoxy acrylate-clay nanocomposite through the simultaneously acrylation reaction of epoxy resin and dispersion of clay nanoparticles under ultrasonic irradiation. The acrylation of diglycidyl ether of bisphenol-A epoxy resin was carried out through the reaction with acrylic acid in the presence of different nanoclays. In addition to UV-curing agents, two different types of commercial organoclays namely, Cloisite 15A and Cloisite 30B were used in nanocomposite films. The degree of epoxy acrylation and the UV-curing process of nanocomposite films were monitored by the corresponding absorption bands in FTIR spectroscopy. The degree of epoxy acrylation reached up to 85% for 30 min ultrasonication with a rather good degree of dispersion for both organoclays as evidenced in XRD patterns and SEM and TEM micrographs. The comparative study of different UV-cured nanocomposites films were carried out by means of different thermal and mechanical test such as DSC, TGA, DMTA and the surface hardness. The significant improvements in glass transition temperature and the thermal stability of different nanocomposites were attributed mainly to effective interactions between clay platelets and epoxy acrylate chains which result in proper dispersion of clay platelets.

The effects of organoclay on the morphology and mechanical properties of PAI/clay nanocomposites coatings prepared by the ultrasonication assisted process

In this research, solvent based polyamide – imide (PAI)/clay nanocomposites were prepared successfully using the solution dispersion technique. With the assistance of the ultrasonic wave, the effect of the ultrasonic wave time on the microstructure of 3wt% PAI/C20A nanocomposite (NC) was investigated. Then, the best ultrasonic parameters were selected and the effects of the concentration of Cloisite 20A (C20A) (1, 3 and 5wt% C20A) on the microstructure and mechanical properties (adhesion, hardness, flexibility, wear and impact) of NCs were investigated. The PAI, C20A and nanocomposites (NC)s were characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX), and Wide-angle X-ray diffraction (WAXD). The results showed that the sample with 1 and 3wt% C20A had better mechanical properties, as compared to the pure PAI and the 5wt% NC.

Development of acrylic‐based powder coatings with incorporation of montmorillonite clays

ABSTRACTPowder coatings have been receiving attention because they are environmentally friendly. They do not contain solvents in their composition, and their components have decorative and corrosion‐protection functions, among many others. However, the presence of polymers in their composition increases the risk of combustion in adverse situations. In this context, this study aims to develop and characterize acrylic‐based powder paints with the addition of 2 wt % and 4 wt % montmorillonite clays (MMT) as Cloisite 30B (MMT‐30B) and Cloisite 15A (MTT‐15A), employed as flame retardants. The characterization of the coatings was carried out by thermogravimetric analysis (TGA), X‐ray diffraction, and scanning electron microscopy. After application of the coatings on carbon steel substrates, flammability tests were performed. The coatings with 2 wt % MMT‐30B showed overall better results, especially in the flammability tests. Flames spread less on these coatings than on the other systems. However, when the surface and bottom temperatures were analyzed by the cone calorimeter test, the samples prepared with 4 wt % MMT‐15A were considered safer to be applied in fire scenarios. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45031.

Micro and nanocomposites of polybutadienebased polyurethane liners with mineral fillers and nanoclay: thermal and mechanical properties

AbstractMicro and nanocomposites of hydroxyl terminated polybutadiene (HTPB)-based polyurethanes (NPU) were obtained using five mineral fillers and Cloisite 20A nanoclay, respectively. Samples were prepared by the reaction of HTPB polyol and toluene diisocyanate (TDI), and the chain was further extended with glyceryl monoricinoleate to produce the final elastomeric polyurethanes. Mechanical and thermal properties were studied, showing that mineral fillers (20%w/w) significantly increased tensile strength, in particular nanoclay (at 5% w/w). When nanoclay-polymer dispersion was modified with a silane and hydantoin-bond promoter, elongation at break was significantly increased with respect to NPU with C20A. Thermal properties measured by differential scanning calorimetry (DSC) were not significantly affected in any case. The molecular structure of prepared micro and nanocomposites was confirmed by Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. Interaction of fillers with polymer chains is discussed, considering the role of silanes in compatibilization of hydrophilic mineral fillers and hydrophobic polymer. The functionalization of nanoclay with HMDS silane was confirmed using FTIR. Microstructure of NPU with C20A nanoclay was confirmed by Atomic Force Microscopy (AFM).

PBAT/organoclay composite films: preparation and properties

Environmental problems caused by the increased waste associated with short-term use of plastic materials, particularly by the food packaging industry, prompted the search for biodegradable alternatives. This contribution studied one of these alternatives, poly(butylene adipate-co-terephthalate)—PBAT, a polymer that is fully biodegradable in common landfills, compounded with a small amount of Cloisite 20A organoclay. Materials were mixed in a laboratory internal mixer and films prepared in a chill roll extruder. Results show that the presence of organoclay does not increase degradation of the polymer matrix during processing, nor affects its crystallization characteristics. However, organoclay addition significantly diminished oxygen and carbon dioxide permeability of the films, making them a very interesting alternative for the food packaging industry.

Investigation of diffusion and cure kinetic in nanoclay-reinforced unsaturated polyester resin

The cure kinetics parameters of unsaturated polyester (UP) resin and unsaturated polyester resin containing 3wt% Cloisite 10A (UP/10A) have been evaluated by three different kinetic approaches using non-isothermal differential scanning calorimetry (DSC) data. In the first method, dependence of activation energy, pre-exponential factor and reaction model on the degree of conversion has been calculated using an Advanced Integral Isoconversional method. In the second method, kinetic parameters of Kamal model and Chern diffusion factor have been computed using experimental data. In the third method, the Sbirrazzuoli diffusion factor kinetic parameters have been evaluated using the activation energy dependence on the degree of conversion. The results show that the addition of Cloisite 10A to UP resin causes the diffusion occurs earlier. According to the results, by adding nanoclay, activation energy and pre-exponential factor of chemical reaction and diffusion are decreased.

Polylactide/organically modified montmorillonite composite fibers

Direct pyrolysis mass spectrometry technique was applied to investigate the characteristics of polylactide, (PLA) nanofibers containing organically modified montmorillonites, Cloisite 15A, (C15A) Cloisite 20A, (C20A) and Cloisite 30B, (C30B) prepared by electrospinning. As the amount of Cloisite present in the composites was increased, the fiber diameters became slightly narrower compared to neat PLA fiber due to the presence of quaternary ammonium salt as organic modifier increasing electrical conductivity. The diameters of the fibers were smallest for PLA/C15A composite and largest for PLA/C30B composite. This behavior was directly related to the amount of organic modifier present in the nanoclays. Significant increase in the thermal stability of PLA composite nanofibers was detected compared to not only neat PLA and PLA fiber but also compared to PLA/organoclay composites and associated with the increase in extent of delamination evidenced by pyrolysis mass spectrometry results.

Presence of vacuoles in natural rubber–Cloisite 15A nanocomposites

ABSTRACTWe studied natural rubber (NR) filled with frequently used organoclay Cloisite 15A using transmission electron microscopy (TEM), cryoporosimetry, and electron spin resonance (ESR) spectroscopy. Quantitative analysis of the TEM micrographs showed a high level of dispersion without the formation of a rigid filler network. The presence of vacuoles was established on the surface of Cloisite 15A; this indicated weak filler–matrix interactions. The mechanism of reinforcement is, therefore, discussed. The volume of vacuoles was found to be proportional to the crosslinking density; this was confirmed with ESR spin‐probe method. The shape of the ESR spectra was highly influenced by the presence of vacuoles. In the NR–Cloisite 10A nanocomposites, vacuoles were absent. The strong interactions implied by this result were confirmed by ESR measurements and are discussed further. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44776.

Effect of shear processing on the linear viscoelastic behaviour and microstructure of bitumen/montmorillonite/MDI ternary composites

Abstract Polymer modified bitumens (PMBs) have largely been utilized as a construction material. However, lack of affinity between bitumen and polymer leads to phase separation, and eventually, performance depletion. In this paper, alternative formulations of bitumen with an organically-modified montmorillonite (OMMT) Cloisite 20A ® and polymeric methylene diphenyl diisocyanate (MDI) were prepared by melt blending. Their comprehensive rheological characterisation evidenced improved linear viscoelastic properties when OMMT is added, revealing a noticeable structural reinforcement and thermal stability. Rheological data also showed that MDI-involved reactions control the composite end properties, being greatly influenced by the shear conditions applied.

Study of the dispersion of Cloisite 10A in recycled polyethylene terephtalate by extrusion

Esta investigación fue enfocada en la dispersión de una arcilla de marca comercial Cloisite 10A en PET reciclado (RPET) para mejorar las propiedades del polímero reciclado que se perdieron en el reprocesamiento de los materiales, específicamente durante la extrusión. Diferentes mezclas de RPET/Cloisite 10A fueron preparadas en un extrusor monohusillo. Las mezclas obtenidas fueron reprocesadas en un extrusor monohusillo tipo reómetro y pasadas a traves de un dado capilar en altos esfuerzos de corte para para incrementar la dispersión de la arcilla en la matriz polimérica. Los resultados muestran degradación física de los materiales. Difracción de rayos X (XRD) indica exfoliación de la arcilla con bajas concentraciones. Además, los resultados reológicos muestran decremento en la viscosidad con incremento de la concentración de la arcilla en las mezclas. Microscopia electrónica de barrido (SEM) revela baja dispersión de la arcilla con incremento de la concentración.

Synergistic Effect of EG and Cloisite 15A on the Thermomechanical Properties and Thermal Conductivity of EVA/PCL Blend

The purpose of this study was to investigate the synergy of expanded graphite (EG) and Cloisite 15A (C15A) on the thermal conductivity and thermomechanical properties of ethylene-vinyl acetate copolymer/poly ( ɛ-caprolactone) (EVA/PCL) blend. Scanning electron microscopy (SEM) results showed that the blend had a phase separation, in which the PCL phase (appeared as droplets) was dispersed uniformly in the EVA matrix in all samples. The results from SEM and X-ray diffraction (XRD) showed that as the EG content increases, graphite sheets increase, leading to a high probability of re-stacking and poor dispersion as well, however the synergy rendered an increase in the storage modulus for the composite containing low content of EG (5phr) in both the EG and clay containing samples. The addition of EG showed a slight increase in thermal stability,but the presence of C15A decreased the onset of degradation of EVA/PCL blend. However, at high temperatures the synergistic effect of EG and C15A showed better thermal stability for EVA/PCL blend than EG alone. The addition and increase in EG content improved thermal conductivity of the EVA/PCL blend in both the clay containing and EG containing samples, however the clay-containing samples showed lower values compared to EG only.

Characterization of silylated modified clay nanoparticles and its functionality in PMMA

The objective of this work was to investigate the effect of single and dual functionalized montmorillonite on the morphology, mechanical and thermal characteristics of the resulting PMMA nanocomposites. In this work, pristine sodium montmorillonite (Cloisite Na+) and commercially organomodified montmorillonite (Cloisite 20A) were modified with silane coupling agent via silylation reaction to increase the clay's compatibility with poly (methyl methacrylate) (PMMA). The resulting nanofillers were then characterized using fourier transform infrared (FTIR), X-ray diffraction (XRD), CHN elemental analysis, nitrogen adsorption-desorption analysis and thermogravimetric analysis (TGA). The PMMA nanocomposites with intercalated structure were successfully fabricated by melt compounding of PMMA with s-Cloisite 20A. It was found that only microcomposites were formed using s-Cloisite Na+ as evidenced by the results obtained by XRD. The structure and morphology of the as-prepared polymer hybrids were further characterized by Scanning Electron Microscopy (SEM). The effect of the interfacial interaction between the polymer and nanofillers, their microstructure as well as the influence of clay loading on the thermal and mechanical properties of the resulting products was also studied by means of TGA and tensile tester and hardness tester. The result shows that the thermal stability and tensile strength of the nanocomposites prepared by twice-modified clay surpassed the neat PMMA and PMMA/s-Cloisite Na+ microcomposites, which is attributed to the formation of more favourable polymer-filler interaction in the PMMA/s-Cloisite 20A nanocomposites.

Thermomechanical properties and bioactivity evaluation of silicone rubber composites

The effect of incorporation of nanofillers (montmorillonite, silica, hydroxyapatite) and bioactive glass (BG) microparticles into a silicone elastomer matrix, on its thermomechanical properties and bioactivity was investigated. The obtained samples were characterized using differential scanning calorimetry and dynamic mechanical analysis, as well as by hardness, tensile, and tear testing, whereas their bioactivity was evaluated by immersion of specimens into simulated body fluid solution and by cell culture experiments (fibroblasts and osteoblasts). Montmorillonites and especially Cloisite 20A have been shown the most efficient reinforcement for improving mechanical properties of silicone rubber composites. On the other hand, BG and silica hybrids exhibited significant bioactive properties. POLYM. COMPOS., 39:2560–2570, 2018. © 2016 Society of Plastics Engineers

Development of an adsorbent via chitosan nano-organoclay assembly to remove hexavalent chromium from wastewater

This study involves nano-biocomposite (chitosan-nanoclay composite, CNC) preparation using solvent casting method with chitosan and organoclay (Cloisite 20A) and investigation of Cr6+ ion adsorption. The influence of contact time, solution pH, initial metal concentration, concentration of the adsorbents and temperature on the removal of Cr6+ ions were examined. Langmuir, Freundlich and Scatchard adsorption isotherms were tested. Maximum adsorption capacity of 128.43mg of Cr6+/g for CNC and 21.83mg of Cr6+/g for chitosan were obtained according to the Scatchard adsorption isotherm at pH of 2 and 3, respectively. Obtained results showed that the adsorption data for Cr6+ ions on CNC correlated well with the Langmuir isotherm model.

Polylactide/organically modified montmorillonite composites; effects of organic modifier on thermal characteristics

The effects of interspace distance and the possible chemical interactions between PLA and the organic modifier of montmorillonites, Cloisite 15A, 20A and 30B on thermal degradation of PLA in the absence and presence of water vapor were investigated by direct pyrolysis mass spectrometry, (DP-MS) in addition to XRD, TEM, DSC, TGA analyses. The DP-MS results clearly showed that the way in which the polymer was incorporated into the nanocomposite strongly depends on the mixing technique, the interspacing between the clay layers and mostly on the type of the organic modifier used. Strong evidences for interactions of the organic modifier of Cloisite 30B with PLA chains resulting in exfoliated structure were detected. In the presence of water vapor, the relative yields of products due to trans-esterification and cis-elimination reactions were diminished. Thermal degradation of PLA nanocomposites was shifted to low temperatures as the partial pressure of H2O was increased.

Water-based polyamide imide – nanoclay coating: Preparation, characterization, thermal stability and visible transparency

Abstract In this study, water-based polyamide-imide (PAI)/clay nanocomposites were prepared using the solution intercalation technique. For this purpose, organo-montmorillonite (Cloisite 20A, C20A) was introduced into water-based polyamide-imide resin matrices. The water-based PAI (WBP)/Cloisite20A (C20A) nanocomposites film and the coating containing 1, 3 and 5 wt% of C20A were prepared using solution intercalation method by blending C20A and WBP solution. The morphology and structure of WBP/C20A nanostructured films containing 1, 3 and 5 wt% organoclay were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray Analysis (EDX). The distribution of C20A in WBP was revealed through XRD, FE-SEM and EDX-map. Furthermore, the thermal decomposition and optical transparency of WBP/C20A nanocomposites were examined. Thermogravimetric analysis and UV–vis spectroscopy indicated that the addition of C20A into the WBP matrix decreased the thermal decomposition temperatures and the optical transparency of the obtained nanocomposites, as compared to the pure WBP.

Morphology and viscoelastic behavior of silicone rubber/EPDM/Cloisite 15A nanocomposites based on Maxwell model

Blends of silicone rubber (SR) and ethylene propylene diene monomer (EPDM) are immiscible due to different polarity and poor interfacial surface tension between their rubber chains. In this study, compatibilizing effect of a nanoclay addition in SR/EPDM blends was investigated. Viscoelasticity and morphology of nanocomposites based on SR and EPDM, containing 10, 20 and 30 wt% of EPDM and 3, 6 and 9 phr of nanoclay (Cloisite 15A), were studied. The curing behavior of the samples showed that the vulcanization rate and cross-link density of the blends increased with increases in SR content. Morphological study was conducted by XRD, SEM and EDX analyses and they indicated that the nanoparticles tended to disperse in the EPDM phase and consequently caused hardness and the elasticity of this phase in nanocomposites increased. Tensile properties of the samples showed a good fitting between that of experiments and the Maxwell model at initial time of testing (1.5 s) for all the blends. Sample parameters including modulus (E), viscosity (η) and relaxation time (τ) calculated by the Maxwell model revealed that those samples with higher content of nanoparticles exhibit higher modulus and lower relaxation time. The good match in tensile properties based on Maxwell model and those of the experimental data was attributed to good dispersion of nanoclay in the blends.

In situ monitoring by DSC and modeling of curing of vinyl polysiloxanes in layered silicate nanocomposites

The study of curing mechanism and the related kinetics in montmorillonite/vinyl-terminated polysiloxane nanocomposites was carried out. Commercially unmodified montmorillonite, as well as two different types of organically modified products, under the trade names: Nanofil 116, Cloisite 20A and Cloisite 30B, respectively, was used as the reinforcing nanofillers. The vulcanization reaction was followed by isothermal and non-isothermal differential scanning calorimetry analysis. The Cloisite 20A/PDMS systems showed increased reaction rate at the early stages of cross-linking, followed by a retardation of the rate and extension of curing time, with respect to the pure PDMS. On the other hand, Cloisite 30B decreases the curing rate of PDMS during the whole process, whereas a significant increase in this parameter was recorded in the case of unmodified clay/PDMS nanocomposites. This diversity of the effect of various types of fillers was attributed to physicochemical interactions between the cross-linking system and organoclay particles mainly due to their surface chemistry. In an attempt to further evaluate the obtained results, it was found that the autocatalytic model shows good fitting with the experimental data.

Using multiple melt blending to improve the dispersion of montmorillonite in polyamide 6 nanocomposites

Polyamide 6 (PA6) was multiple melt-blended with organically modified montmorillonite (MMT) Cloisite 20A and Cloisite 30B and unmodified MMT Na+ in order to make three types of PA6/MMT nanocomposites. According to the morphology observation, the dispersion of silicate layers in the 20A nanocomposites was improved until it scattered, whereas the dispersion of silicate layers in the 30B nanocomposites is satisfactory. Moreover, the dispersion of silicate layers in Na+ nanocomposites slightly improved with the increase in melt-blending cycles. After PA6 was melt-blended with MMT, its molecular weight (MW) decreased with the processing cycles, which resulted in easy degradation. The mechanical property tests show that multiple melt blending has a positive influence on the mechanical properties of three PA6/MMT nanocomposites. However, their elongation at break and impact strength both decrease as a result of the aggravating degradation of PA6. Increasing the melt-blending cycles causes the crystallization temperature to increase and the melting temperature to decrease.

Vibrational energy-harvesting performance of bio-sourced flexible polyamide 11/layered silicate nanocomposite films

ABSTRACTThe energy-harvesting efficiency of melt processed polyamide 11 (PA11) films and its nanocomposites have been investigated as a function of filler type and content. In the present work, nanoclays have been used as structural modifiers in a PA11 matrix. The nanocomposites were prepared using layered clays, Cloisite 20A, 10A, and Na+, by extrusion process through varying the filler content, 1, 2, 4, and 5 wt.%. The crystalline structure of these nanocomposites has been studied by X-ray diffractometer. It has been demonstrated that layered silicates are not significant for the structural quality of the obtained nanocomposites. Regarding the interlayer peak of different clays, it has also been revealed that Cloisite 20A is partially exfoliated, whereas 10A and Na+ are totally exfoliated in the PA11 matrix. From mechanical and dynamic mechanical analyses, it was found that the addition of layered silicates results in an increase in mechanical properties. The piezoelectric strain coefficient d33 and dielectric constant εR have been measured on polarized films at ambient temperature. Among all the prepared nanocomposites only Cloisite Na+-loaded PA11 nanocomposites showed the best piezoelectric constant. This observation showed that piezoelectric constant not only depends on the crystalline phases but also on the nature of the filler. Cloisite Na+ is more polar than other modified clays and high polarity leads to a better polarization response. A specific method for the quantification of energy vibration recovery has been developed for these nanocomposites. The capabilities of vibrational energy recovery were studied on PA11 loaded with Cloisite Na+.