Synthesis and evaluation of high‐performance ethylene–propylene–diene terpolymer/organoclay nanoscale composites

The main objective of this study was to synthesize and characterize the properties of ethylene–propylene–diene terpolymer (EPDM)/clay nanocomposites. Pristine clay, sodium montmorillonite (Na⁺–MMT), was intercalated with hexadecyl ammonium ion to form modified organoclay (16Me–MMT) and the effect of intercalation toward the change in interlayer spacing of the silicate layers was studied by X‐ray diffraction, which showed that the increase in interlayer spacing in Na⁺–MMT by 0.61 nm is attributed to the intercalation of hexadecyl ammonium ion within the clay layers. In the case of EPDM/16Me–MMT nanocomposites, the basal reflection peak was shifted toward a higher angle. However, gallery height remained more or less the same for different EPDM nanocomposites with organoclay content up to 8 wt %. The nanostructure of EPDM/clay composites was characterized by transmission electron microscopy, which established the coexistence of intercalated and exfoliated clay layers with an average layer thickness in the nanometer range within the EPDM matrix. The significant improvement in thermal stability and mechanical properties reflects the high‐performance nanocomposite formation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2429–2436, 2004     

Synthesis and thermal properties of polystyrene/montmorillonite nanocomposites by γ‐ray radiation polymerization

Polystyrene/montmorillonite nanocomposites were prepared by γ‐ray radiation polymerization. X‐ray diffraction and high‐resolution transmission electron microscopy confirmed that polystyrene (PS) could be easily inserted between the sheets of montmorillonite (MMT) to form intercalated nanocomposites. In these PS/MMT nanocomposites, the distance between the sheets of MMT was barely influenced by varying the content of the MMT. Thermal stabilities of the samples were studied by thermal gravimetric analysis and differential scanning calorimetry. The glass‐transition temperature of PS/MMT nanocomposites was obviously higher than that of the pure PS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1692–1696, 2003     

Preparation and properties of EPDM/organomontmorillonite hybrid nanocomposites

Hybrid nanocomposites based on organophillic montmorillonite (MMT) and ethylene–propylene–diene rubber (EPDM) have been prepared by a melt compounding process. From analysis by X‐ray diffraction and transmission electron microscopy, the rubber molecules were found to be intercalated into the galleries of organoMMT and the silicate layers of organoMMT are uniformly dispersed as platelets of 50–80 nm thickness in the EPDM matrix. Dynamic mechanical studies reveal a strong rubber–filler interaction in the hybrid nanocomposite which is manifested in the lowering of tan δ at the glass transition temperature. The hybrid nanocomposites exhibit great improvement in tensile and tear strength, and modulus, as well as elongation‐at‐break. Moreover, the permeability of oxygen for the hybrid nanocomposite was reduced remarkably. © 2002 Society of Chemical Industry     

Effect of organic modifiers and silicate type on filler dispersion,thermal, and mechanical properties of ABS‐clay nanocomposites

Acrylonitrile–butadiene–styrene (ABS)–clay composite and intercalated nanocomposites were prepared by melt processing, using Na‐montmorillonite (MMT), several chemically different organically modified MMT (OMMT) and Na‐laponite clays. The polymer–clay hybrids were characterized by WAXD, TEM, DSC, TGA, tensile, and impact tests. Intercalated nanocomposites are formed with organoclays, a composite is obtained with unmodified MMT, and the nanocomposite based on synthetic laponite is almost exfoliated. An unintercalated nanocomposite is formed by one of the organically modified clays, with similar overall stack dispersion as compared to the intercalated nanocomposites. T_g of ABS is unaffected by incorporation of the silicate filler in its matrix upto 4 wt % loading for different aspect ratios and organic modifications. A significant improvement in the onset of thermal decomposition (40–44°C at 4 wt % organoclay) is seen. The Young's modulus shows improvement, the elongation‐at‐break shows reduction, and the tensile strength shows improvement. Notched and unnotched impact strength of the intercalated MMT nanocomposites is lower as compared to that of ABS matrix. However, laponite and overexchanged organomontmorillonite clay lead to improvement in ductility. For the MMT clays, the Young's modulus (E) correlates with the intercalation change in organoclay interlayer separation (Δd₀₀₁) as influenced by the chemistry of the modifier. Although ABS‐laponite composites are exfoliated, the intercalated OMMT‐based nanocomposites show greater improvement in modulus. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel preparation and properties of EPDM/montmorillonite nanocomposites

This article reports on a novel route to develop ethylene–propylene–diene rubber (EPDM)/montmorillonite nanocomposites Modification of the MMT was carried out with maleic anhydride (MA), which acts as the intercalation agent for MMT and the vulcanizing agent for EPDM matrix, as well as the compatibilizer for the EPDM and MMT phases. The effect of MA‐modified MMT in nanocomposites was investigated by focusing on three major aspects: structural analysis, thermal properties, and material properties. The d‐spacings of both the MA modified MMT and exfoliated nanocomposites were investigated by X‐ray diffraction (XRD), and the morphology of these nanocomposites was examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Dynamic mechanical analysis confirms the constraint effect of exfoliated MMT layers on EPDM chains, which benefited the increased storage modulus, increased glass transition temperature. Thermogravimetric analysis indicates that there is some enhancement in degradation behavior between the nanocomposites and EPDM matrix. The nanocomposites exhibit great improvement in tensile strength and modulus, as well as elongation‐at‐break. The effects of MA addition on the formation of nano‐metric reinforcement and on the mechanical properties of nanocomposites are discussed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2578–2585, 2006     

Ethylene propylene diene terpolymer/ethylene vinyl acetate/layered silicate ternary nanocomposite by solution method

A new ternary nanocomposite has been developed using ethylene propylene diene terpolymer (EPDM), ethylene vinyl acetate (EVA‐45) copolymer, and organically modified layered silicate (16 Me‐MMT) from sodium montmorillonite (Na⁺‐MMT). Wide angle X‐ray diffraction and transmission electron microscopic analysis confirmed the intercalation of the polymer chains in between the organosilicate layers and the nanoscale distribution of 16 Me‐MMT in polymer matrix, respectively. The measurement of mechanical properties for 2–8 wt% of 16 Me‐MMT loadings showed a significant increase in tensile strength, elongation at break, and modulus at different elongations. Such an improvement in mechanical properties has been correlated based on the fracture behavior of nanocomposite by SEM analysis. Thermal stability of EPDM/EVA/layered silicate ternary nanocomposites also showed substantial improvements compared with the neat EPDM/EVA blend, confirming thereby the formation of a high performance nanocomposite. POLYM. ENG. SCI., 46:437–843, 2006. © 2006 Society of Plastics Engineers     

Effect of layered silicate on EPDM/EVA blend nanocomposite: Dynamic mechanical,thermal, and swelling properties

Polymer blend nanocomposites have been developed by solution method using ethylene propylene diene terpolymer (EPDM), ethylene vinyl acetate (EVA‐45) copolymer, and organically modified layered silicate. Morphological investigation made by wide‐angle X‐ray diffraction and transmission electron microscopic analysis indicates intercalated structure of EPDM/EVA nanocomposites with partial disorder. Scanning electron microscopic studies exhibit the phase behavior of EPDM/EVA blend nanocomposites. Dynamic mechanical thermal analysis shows a significant increase in storage modulus in the rubbery plateau. The decrease in damping (tan δ) value and enhanced glass‐transition temperature (T_g) demonstrate the reinforcing effect of layered silicate in the EPDM/EVA blend matrix. The tensile modulus of these nanocomposites also showed a significant improvement with the filler content. The main chain scission of EPDM/EVA blend nanocomposites compared with the neat EPDM/EVA blend showed substantial improvement in thermal stability in nitrogen, whereas a sizeable increase is observed in air. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Flame‐retarding mechanism of organically modified montmorillonite and phosphorous‐Nitrogen flame retardants for the preparation of a halogen‐free,flame‐retarding thermoplastic poly(ester ether) elastomer

In this study, thermoplastic poly(ester ether) elastomer (TPEE) nanocomposites with phosphorus–nitrogen (P–N) flame retardants and montmorillonite (MMT) were prepared by melt blending. The fire resistance of the nanocomposites was analyzed by limiting oxygen index (LOI) and vertical burning (UL 94) tests. The results show that the addition of the P–N flame retardants increased the LOI of the material from 17.3 to 27%. However, TPEE containing P–N flame retardants only obtained a UL 94 V‐2 ranking; this resulted in a flame dripping phenomenon. On the other hand, TPEE containing the P–N flame retardant and organically modified montmorillonite (o‐MMT) achieved better thermal stability and good flame retardancy; this was ascribed to its partially intercalated structure. The synergistic effect and synergism were investigated by Fourier transform infrared spectroscopy and thermogravimetry. The introduction of o‐MMT decreased the inhibition action of the P–N flame retardant and increased the amount of residues. The catalytic decomposition effect of MMT and the barrier effect of the layer silicates are discussed in this article. The residues after heating in the muffle furnace were analyzed by scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and laser Raman spectroscopy. It was shown that the intercalated layer silicate structure facilitated the crosslinking interaction and promoted the formation of additional carbonaceous char residues in the formation of the compact, dense, folded‐structure surface char. The combination of the P–N flame retardant and o‐MMT in TPEE resulted in a better thermal stability and fire resistance because of the synergistic effect of the mixture. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41094.     

Effect of clay modification on the morphological,mechanical, and thermal properties of polyamide 6/polypropylene/montmorillonite nanocomposites

Polyamide 6/polypropylene (PA6/PP = 70/30 parts) blends containing 4 phr (parts per hundred resin) of organophilic montmorillonite (OMMT) were prepared by melt compounding. The sodium montmorillonite (Na‐MMT) was modified using three different types of alkyl ammonium salts, namely dodecylamine, 12‐aminolauric acid, and stearylamine. The effect of clay modification on the morphological and mechanical properties of PA6/PP nanocomposites was investigated using x‐ray diffraction (XRD), transmission electron microscopy (TEM), tensile, flexural, and impact tests. The thermal properties of PA6/PP nanocomposites were characterized using thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and heat distortion temperature (HDT). XRD and TEM results indicated the formation of exfoliated structure for the PA6/PP nanocomposites prepared using stearylamine modified montmorillonite. On the other hand, a mixture of intercalated and exfoliated structures was found for the PA6/PP nanocomposites prepared using 12‐aminolauric acid and dodecylamine modified montmorillonite. Incorporation of OMMT increased the stiffness but decreased the ductility and toughness of PA6/PP blend. The PA6/PP nanocomposite containing stearylamine modified montmorillonite showed the highest tensile, flexural, and thermal properties among all nanocomposites. This could be attributed to better exfoliated structure in the PA6/PP nanocomposite containing stearylamine modified montmorillonite. The storage modulus and HDT of PA6/PP blend were increased significantly with the incorporation of both Na‐MMT and OMMT. The highest value in both storage modulus and HDT was found in the PA6/PP nanocomposite containing stearylamine modified montmorillonite due to its better exfoliated structure. POLYM. COMPOS., 31:1156–1167, 2010. © 2009 Society of Plastics Engineers     

Preparation and characterization of polystyrene–clay nanocomposites by free‐radical polymerization

The polymerizable cationic surfactant, vinylbenzyldimethylethanolammouium chloride (VBDEAC), was synthesized to functionalize montmorillonite (MMT) clay and used to prepare exfoliated polystyrene–clay nanocomposites. The organophilic MMT was prepared by Na⁺ exchanged montmorillonite and ammonium cations of the VBDEAC in an aqueous medium. Polystyrene–clay nanocomposites were prepared by free‐radical polymerization of the styrene containing intercalated organophilic MMT. Dispersion of the intercalated montmorillonite in the polystyrene matrix determined by X‐ray diffraction reveals that the basal spacing is higher than 17.6 nm. These nanocomposites were characterized by differential scanning calorimetry (DSC), transmission electron micrograph (TEM), thermal gravimetric analysis (TGA), and mechanical properties. The exfoliated nanocomposites have higher thermal stability and better mechanical properties than the pure polystyrene. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1370–1377, 2002     

Synthesis and properties of poly(methyl methacrylate)/clay nanocomposites using natural montmorillonite and synthetic Fe‐montmorillonite by emulsion polymerization

In this article, Fe‐montmorillonite (Fe‐MMT) was synthesized by hydrothermal method. For the first time, Fe‐MMT was modified by cetyltrimethyl ammonium bromide (CTAB), and poly(methyl methacrylate)(PMMA)/Fe‐MMT nanocomposites were synthesized by emulsion polymerization. Then poly(methyl methacrylate)(PMMA)/natural montmorillonite (Na‐MMT) and PMMA/Fe‐MMT nanocomposites were compared by Fourier transform infrared (FTIR) spectra, X‐ray diffraction (XRD) patterns, transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA). By XRD and TEM, it was found out that the morphology of PMMA/Fe‐MMT nanocomposites was different from that of the PMMA/Fe‐MMT nanocomposites when the content of two types of clay was same in the PMMA matrix. It was possible that the presence of iron may lead to some radical trapping, which enhances intragallery polymerization to be developed to improve layer dispersion in PMMA/Fe‐MMT systems. In TGA curves, the thermal stability and residue at 600°C of PMMA/Fe‐MMT nanocomposites were higher than those of PMMA/Na‐MMT nanocomposites. Those dissimilarities were probably caused by structural Fe ion in the lattice of Fe‐MMT. POLYM. COMPOS., 27:49–54, 2006. © 2005 Society of Plastics Engineers     

Synthesis of poly(butyl acrylate‐co‐methyl methacrylate)/montmorillonite waterborne nanocomposite via semibatch emulsion polymerization

Poly(butyl acrylate‐co‐methyl methacrylate)‐montmorillonite (MMT) waterborne nanocomposites were successfully synthesized by semibatch emulsion polymerization. The syntheses of the nanocomposites were performed in presence of sodium montmorillonite (Na‐MMT) and organically modified montmorillonite (O‐MMT). O‐MMT was used directly after the modification of Na‐MMT with dimethyl dioctadecyl ammonium chloride. Both Na‐MMT and O‐MMT were sonified to obtain nanocomposites with 47 wt % solids and 3 wt % Na‐MMT or O‐MMT content. Average particle sizes of Na‐MMT nanocomposites were measured as 110–150 nm while O‐MMT nanocomposites were measured as 200–350 nm. Both Na‐MMT and O‐MMT increased thermal, mechanical, and barrier properties (water vapor and oxygen permeability) of the pristine copolymer explicitly. X‐ray diffraction and transmission electron microscope studies show that exfoliated morphology was obtained. The gloss values of O‐MMT nanocomposites were found to be higher than that of the pristine copolymer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42373.     

Preparation of exfoliated high‐impact polystyrene/MMT nanocomposites via in situ polymerization under controlling viscosity of the reaction medium

Exfoliated high‐impact polystyrene (HIPS)/montmorillonite (MMT) nanocomposites were prepared via in situ polymerization of styrene in the presence of polybutadiene, using an intercalated cationic radical initiator‐MMT hybrid (organoclay). In the solution polymerization in toluene, the silicate layers of the clay were well exfoliated, due to the low extra‐gallery viscosity that can facilitate the diffusion of styrene monomers into the clay layers during the polymerization. The exfoliated HIPS/MMT nanocomposites were also successfully prepared by controlling the viscosity of the reaction medium with prolong swelling of the organoclay in styrene, prior to bulk polymerization. The HIPS/MMT nanocomposites, obtained from bulk polymerization, exhibited a significant improvement in thermal stability, compared to those obtained from solution polymerization as well as the pure polymer counterparts. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers     

A polymeric flame retardant and surfactant‐free montmorillonite nanocomposites: Preparation and exfoliation mechanism discussion

A polymeric flame retardant (PDEPD) and various amounts of sodium montmorillonite (Na‐MMT) nanocomposites with exfoliation structure were prepared via one‐step polycondensation, attempting to prepare flame‐retardant nanocomposites. The nanocomposites exhibited high thermal stability at high temperature. Based on several comparative studies, we investigated and proposed the possible exfoliation mechanism of Na‐MMT in PDEPD substrate. The microscale combustion calorimeter and cone calorimeter results showed the PDEPD/Na‐MMT nanocomposites could significantly improve the flame retardancy of polystyrene and polyurethane elastomer (TPU), especially the TPU matrix. This study provides new viewpoint for preparing flame‐retardant nanocomposites without surfactants. POLYM. COMPOS., 35:167–173, 2014. © 2013 Society of Plastics Engineers     

Influence of annealing treatment on the heat distortion temperature of nylon‐6/montmorillonite nanocomposites

It has been recognized that the incorporation of nanoscale montmorillonite (MMT) layers into polymer matrix enhances significantly the heat resistance of the resultant nanocomposites, especially for nylon‐6 (N6)/clay nanocomposites (NCNs). In the present work, the heat distortion temperature (HDT) of NCNs, including the intercalated N6/Na‐montmorillonite (Na‐MMT) and the exfoliated N6/organo‐montmorillonite (OMMT) ones, have been investigated for both non‐annealed and annealed testing specimens in comparison with the neat N6. As expected, the incorporation of MMT obviously improved HDT of NCNs, with the highest HDT value obtained in the N6/OMMT system due to its exfoliated nano‐structure. After an annealing treatment at 80°C for 6 hr, the HDT revealed noticeable increase for all the samples, particularly for the intercalated N6/Na‐MMT nanocomposite that showed the highest increment of 34°C. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and Fourier transform infrared (FTIR) techniques were employed to clarify the origin of the variation in HDT after annealing, and the results suggest that the increases in the crystallinity, the glass transition temperature, and the order degree of hydrogen bonding may account for the noticeable increases in the HDT of the nanocomposites after annealing. POLYM. ENG. SCI., 45:1247–1253, 2005. © 2005 Society of Plastics Engineers     

Preparation and characterization of polymer/organosilicate nanocomposites based on unmodified LDPE

Low‐density polyethylene (LDPE)/silicate nanocomposites were prepared by the melt compounding and solution blend methods using unmodified LDPE polymer and layered silicates with different aspect ratio. X‐ray diffraction (XRD) analysis performed on composites obtained by dispersing the organosilicates in molten LDPE evidenced an exfoliated or partially exfoliated structure for the low aspect ratio silicate (laponite) in contrast to the high aspect ratio silicate (montmorillonite), which led to the formation of intercalated nanocomposites. With regard to the preparation method, the melt compounding method was more effective in forming exfoliated/highly intercalated LDPE nanocomposites compared with the solution blend method (using CCl₄ as a solvent). A gradual increase in crystallization temperatures (T_c) with increasing laponite content for LDPE‐organolaponite nanocomposites was revealed by differential scanning calorimetry (DSC) measurements. Thermogravimetric analysis and tensile measurements results indicated that thermal stability and elastic modulus increment were more prevalent for nanocomposites prepared using organomontmorillonite as filler. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of poly(methyl methacrylate)/montmorillonite nanocomposites by in situ bulk polymerization

Poly(methyl methacrylate)/montmorillonite (MMT) nanocomposites were prepared by in situ bulk polymerization. The results showed that the silicone coupling agent affected the structure and properties of hybrid materials. XRD analysis showed that the dispersion of clay in nanocomposites with silicone‐modified organophilic MMT was more ordered than that in nanocomposites with unmodified organophilic MMT. The glass transition temperature (T_g) of the nanocomposites was 6–15°C higher and the thermal decomposition temperature (T_d) was 100–120°C higher than those of pure PMMA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2256–2260, 2003     

Thermal–oxidative degradation and accelerated aging behavior of polyamide 6/epoxy resin‐modified montmorillonite nanocomposites

Polyamide 6 (PA6) nanocomposites based on epoxy resin‐modified montmorillonite (EP‐MMT) were prepared by melt processing using a typical twin‐screw extruder. X‐ray diffraction combined with transmission electron microscopy was applied to elucidate the structure and morphology of PA6/EP‐MMT nanocomposites, suggesting a nearly exfoliated structure in the nanocomposite with 2 wt % EP‐MMT (PA6/2EP‐MMT) and a partial exfoliated‐partial intercalated structure in PA6/4 wt %EP‐MMT nanocomposite (PA6/4EP‐MMT). The thermogravimetric analysis under air atmosphere was conducted to characterize the thermal–oxidative degradation behavior of the material, and the result indicated that the presence of EP‐MMT could inhibit the thermal‐oxidative degradation of PA6 effectively. Accelerated heat aging in an air circulating oven at 150°C was applied to assess the thermal–oxidative stability of PA6 nanocomposites through investigation of reduced viscosity, tensile properties, and chemical structure at various time intervals. The results indicated that the incorporation of EP‐MMT effectively enhanced the thermal–oxidative stability of PA6, resulting in the high retention of reduced viscosity and tensile strength, and the low ratio of terminal carboxyl group to amino group. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40825.     

Effects of silane grafting on the morphology and thermal stability of poly(ethylene terephthalate)/clay nanocomposites

An alkylammonium intercalated montmorillonite (A‐MMT) was modified by edge grafting with 3‐glycidoxypropyltrimethoxysilane. In comparison with poly(ethylene terephthalate) (PET)/A‐MMT, the resultant grafted clay, S‐A‐MMT, exhibited improved miscibility with PET matrix and revealed better dispersion state in the melting compounded PET/S‐A‐MMT nanocomposites. As a result, the PET/S‐A‐MMT nanocomposite had slower degradation rate owing to the enhanced clay barrier effect. Meanwhile, the nanocomposite exhibited lower degradation onset temperature under nitrogen because of the clay catalysis effect, which can be explained by the decreasing degradation reaction energy calculated from Coats–Redfern method of degradation kinetics. In the other hand, nanocomposite with better clay dispersion state exhibited increasing thermal oxidative stability due to clay barrier effect of hindering oxygen to diffuse in, which accorded with the continuous and compact char surface formed during polymer degradation. The clay catalysis and barrier effect of silicate layers were presented directly in isothermal oxidative TGA experiment. Furthermore, the mechanical and crystallization properties of PET/clay nanocomposites were investigated as well. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Study of nanocomposites prepared by melt blending TPU and montmorillonite

The intercalated thermoplastic polyurethane (TPU)/montmorillonite (MMT) nanocomposites were prepared by melt blending TPU and organic octadecylammonium‐treated MMT (ODA‐MMT) at 150–155°C for 10 min. Compared with those of TPU/montmorillonite composites, the interface interaction and dispersion of TPU/ODA‐MMT nanocomposites were improved remarkably. The tensile strength and tear strength of the TPU/ODA‐MMT nanocomposites were higher than those of pure TPU, and the MMT platelets dispersed on the nanometer scale in TPU matrix had reinforce effect. Due to the “labyrinth” effect of the MMT platelets dispersed on the nanometer scale in the TPU matrix caused by the eximious barrier and strong interaction between the MMT platelets and TPU, the temperature of initial weight loss of the TPU/ODA‐MMT nanocomposites was higher than that of pure TPU and TPU/MMT composites in the second thermodegradation step. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers