Synthesis and characterization of polymer–nanoclay conductive nanocomposites

Polymer–clay nanocomposites based on poly(3,4‐ethylenedioxythiophene)/polystyrene sulfonate (PEDOT) : PSS and nanoclay montmorillonite were synthesized and characterized. The doping of PEDOT with polystyrene sulfonate made it water dispersible (PEDOT–PSS). Sodium dodecyl benzene sulfonate (SDBS) and ionic liquid were used to increase the interlayer spacing and the conductivity of the nanocomposites, respectively. The nanocomposite was characterized by various techniques, such as X‐ray diffraction (XRD), TEM, surface resistivity, and thermogravimetric measurement analysis. Interlayer spacing increased as a result of the addition of SDBS, and this was confirmed by the 2θ shift observed via XRD analysis. The surface morphology of the conductive coated clay was examined by TEM analysis. Good electrical surface conductivity, interlayer spacing, and polymer coating were observed for the material prepared using the surfactant and conductive ionic liquid. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and investigation of the physical and chemical properties of clay-based polyacrylamide/Cr (III) hydrogels as a water shut-off agent in oil reservoirs

The effects of clay (montmorillonite and kaolinite) in the hydrogels were investigated on various properties such as syneresis and strength of thermal and salinity situations in one of the southern Iranian oil reservoirs. The X-ray diffraction (XRD) patterns exhibited a significant increase in interplanar spacing between the montmorillonite clay layers, varying from the initial value of 12.43 °A to 19.45 °A, which evidences the intercalation formation. It was revealed that even increasing of the interlayer spacing due to kaolinite modification had no effect on the clay compositions. Formation water was used to study the strength of the hydrogel in the presence of ions. The results indicated that 15 wt% increase of kaolinite clay (modified and non-modified) leads to 20% decrease of the hydrogels’ syneresis. The diffusion of polymer chains between the clay layers increased the elastic modulus (G′) of the prepared hydrogels with modified kaolinite and montmorillonite, where the maximum value of G’ was observed in 3 wt% of montmorillonite. Finally, the thermogravimetric analysis (TGA) indicated an increase in the thermal stability of the mentioned hydrogels.     

Preparation and characteristics of nitrile rubber (NBR) nanocomposites based on organophilic layered clay

The effect of clay modification on organo‐montmorillonite/NBR nanocomposites has been studied. Organo‐montmorillonite/NBR nanocomposites were prepared through a melt intercalation process. NBR nanocomposites were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), dynamic mechanical thermal analysis (DMTA) and a universal testing machine (UTM). XRD showed that the basal spacing in the clay increased, which means that the NBR matrix was intercalated in the clay layer galleries. On TEM images, organo‐montmorillonite (MMT) particles were clearly observed, having been exfoliated into nanoscale layers of about 10–20 nm thickness from their original 40 µm particle size. These layers were uniformly dispersed in the NBR matrix. The DMTA test showed that for these nanocomposites the plateau modulus and glass transition temperature (T_g) increased with respect to the corresponding values of pure NBR (without clay). UTM test showed that the nanocomposites had superior mechanical properties, ie strength and modulus. These improved properties are due to the nanoscale effects and strong interactions between the NBR matrix and the clay interface. Copyright © 2003 Society of Chemical Industry     

Dynamic properties of rubber vibration isolators and antivibration performance of a nanoclay‐modified silicone/poly(propylene oxide)–poly(ethylene oxide) copolymer with 20 wt % LiClO4 blend system

This research explores the interlayer effect, hysteresis behavior, and dynamic antivibration properties of a poly(propylene oxide)–poly(ethylene oxide) copolymer with 20 wt % LiClO₄ (PEL) for modified silicone [silicone/polymer electrolyte (SP)] blends with clay and organoclay in various amounts. The results show that the polymer chains of PEL expand the clay gallery distance from 1.21 to 1.84 nm. Clay, after it has been organically modified, is added to SP blends, and its gallery spacing shortens from 2 to 1.7 nm. From the compression hysteresis results, along with the increased content of unmodified clay, the antivibration performance of the blends is elevated. In the dynamic antivibration testing results, along with the addition of clay and organoclay, the dynamic ratio of the blends is decreased; thus, in the vibration isolation performance, there is evidence of an elevated effect. On the other hand, after the clay is modified with ammonium salt, its vibration isolation effect is not better than that of the unmodified clay. In terms of the formulation of the nanocomposites, when the concentration of the clay is less than 4 wt %, it has a better effect on the vibration isolation and antivibration effect of SP blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3713–3720, 2006     

Intercalation behavior of hydroxylated dendritic polyesters in polymer clay nanocomposites prepared from aqueous solution

Second and fourth generations of hydroxylated dendritic polyesters based on 2,2-bis-methylopropionic acid (bis-MPA) with an ethoxylated pentaerytriol (PP50) core were combined with unmodified sodium montmorillonite clay (Na⁺MMT) in water to generate a broad range of polymer clay nanocomposite films from 0 to 100% wt/wt. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate intercalation states of the clay galleries. Intercalation was the dominant state in these nanocomposites. Significant exfoliation was only observed within 0–5% wt/wt of mineral composition range. It was shown that interlayer spacing changed within the composition range 5–95% wt/wt from 0.5 nm to up to 3.5 nm in a step-like fashion with 0.5 nm increments which corresponded to a flattened conformation of confined hyperbranched polymers (HBP). Second and fourth generations exhibited the same layer-by-layer intercalation of completely flattened HBPs. No dependence of interlayer spacings on generation number was found. XRD and TEM revealed the presence of mixed intercalated populations with interlayer spacings at multiples of 0.5 nm.     

SYNTHESIS OF POLY(METHYL METHACRYLATE)—CLAY NANOCOMPOSITES

Poly(methyl methacrylate)/clay nanocomposites were synthesized via in situ free radical polymerization of methyl methacrylate (MMA) in the presence of functionalized clay. Montmoril-lonite (MMT), a smectic type of clay, was treated with a commercial cationic surfactant, benzalkonium chloride (BAC), and a synthesized zwitterionic surfactant, octadecyldimethyl betaine (CI8DMB) Functionalized MMT was prepared via an ion exchange between Na,ions in the clay and the surfactant cations in aqueous medium. The intercalation of the surfactant in the clay galleries was determined using X-ray diffraction (XRD). The interlayer spacing for C18DMB was 2.03nm, higher than 1.86nm observed for BAC. This is due to longer chain length of C18DMB. Both organophilic clays formed a viscous gel when dispersed in the monomer, MMA. Poly(methyl methacrylate) (PMMA) nanocomposites were obtained by polymerizing the dispersions. XRD and transmission electron microscopy (TEM) indicate predominant exfoliation of the silicate layers in the polymer matrix for MMT treated with C18DMB, and partial exfoliation for MMT treated with BAC     

Unusual exfoliation of layered silicate clays by non-aqueous amine diffusion mechanism

The organic ionic exchange intercalation of smectite clays is conventionally performed in water swelling conditions. Here we report a different mechanism for modifying the smectite clays in alcohol solvents. The modification of sodium montmorillonite with poly(oxyethylene-oxypropylene)-amines (POA-amine) were compared for the differences between in water and in alcohol. In water, the intercalation of hydrophobic poly(oxypropylene)-rich amines in the silicate galleries expands the interlayer spacing up to 10 nm and even to exfoliation (featureless in X-ray diffraction pattern) with over 5 amine equivalents, where as hydrophilic poly(oxyethylene)-rich amines could only intercalate in a low spacing of 1.8 nm. On the other hand, all of the POA-amines in isopropanol afford the exfoliation with over, 3 amine equivalents. The mechanism of this unexpected exfoliation is explained by the thermodynamic formations of an imaginary membrane surrounding the clay units, followed by amine diffusion from the solvent into the clay galleries.     

Ethylene–octene copolymer (engage)–clay nanocomposites: Preparation and characterization

In this work, preparation and properties of nanoclay modified by organic amine (octadecyl amine, a primary amine) and Engage (ethylene–octene copolymer)–clay nanocomposites are reported. The clay and rubber nanocomposites have been characterized with the help of Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X‐ray diffraction (XRD). The X‐ray results suggest that the intergallery spacing of pristine clay increases with the incorporation of the amine. The XRD peak observed in the range of 3–10° for the modified clay also disappears in the rubber nanocomposites at low loading. TEM photographs show exfoliation of the clays in the range of 10–30 nm in Engage. In the FTIR spectra of the nanocomposite, there are common peaks for the virgin rubber as well as those for the clay. Excellent improvement in mechanical properties, like tensile strength, elongation at break, and modulus, is observed on incorporation of the nanoclay in Engage. The storage modulus increases, tan δ peak decreases, and the glass transition temperature is shifted to higher temperature. The results could be explained with the help of morphology, dispersion of the nanofiller, and its interaction with the rubber. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 603–610, 2006     

Morphology and properties of silane‐modified montmorillonite clays and clay/PBT composites

Commercially available organoclay (Closite 30B) was modified by using 3‐aminopropyltriethoxysilane (APS) via a silylation reaction. Sodium clay (Closite Na) was treated by APS directly as a control. Such modified clays were further melt‐compounded with polybutylene terephthalate (PBT). The morphology and properties of the modified organoclays were characterized with X‐ray diffraction (XRD), transmission electrical microscopy (TEM), Infra‐red spectroscopy, contact angle measurement, and thermogravimetric analysis (TGA). The effects of modified clays on the crystallization behavior of PBT were characterized by differential scanning calorimetry. The basal spacing of Closite Na was enlarged from 1.01 to 1.41 nm after APS treatment, indicating that the APS was intercalated into the clay intergalleries as a monolayer. The basal spacing of Closite 30B increased slightly after APS treatment, partially resulted from the reactions between the APS and hydroxyl groups on the intercalant of Closite 30B. Closite 30B was found to be exfoliated disorderly after melt‐compounded with PBT. The APS‐modified Closite 30B only dispersed as swollen elliptical clay aggregates, in which the silicate layers were orderly intercalated. TGA results showed that the decomposition temperature at 5% weight loss of Closite 30B was increased from 250 to 270°C after APS treatment. A significant increase in the degree of crystallinity of PBT was observed in the exfoliated PBT/30B composite. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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     

Morphology,Thermal and Mechanical Properties of Biodegradable Poly(butylene succinate)/Poly(butylene adipate-co-terephthalate)/Clay Nanocomposites

Sodium montmorillonite (Na-MMT) was successfully modified by octadecylamine (ODA) through a cation exchange technique that showed by the increased of basal spacing of clay by XRD. The addition of the organoclay into the PBS/PBAT blends produced intercalated-type nanocomposites with improvements in tensile modulus and strength. The highest tensile strength of nanocomposite was observed at 1 wt% of organoclay incorporated. A TGA study showed that the thermal stability of the blend increased after the addition of the organoclay by 1 wt%. SEM micrographs of the fracture surfaces show that the morphology of the blend becomes smoother with presence of organoclay.     

Organo-Pillared-Clay: Synthesis,Characterization, and Applications for Treatment of Perfluoroalkyl Substances

Anthropogenic toxic pollutants are ubiquitous and need to be removed from the environment. This study investigates the preparation of an inorganic-organic modified clay (organo-pillared-clay) for the removal of contaminants. The present work investigates the compositional, structural and sorption properties of modified clay materials for the removal of perfluoroheptanoic acid (PFHpA). The chemical compositions of the clay materials used were determined by interlayer and surface analysis. The results showed changes in interlayer spacing and external surface area due to modification and surfactant addition during the cation exchange reaction. The combination of adsorption and irradiation increased removal efficiency, although photodegradation was partially inhibited. Modified clays show promise for PFHpA remediation, with potential for optimizing photodegradation processes.     

Nanoencapsulation of montmorillonite clay within poly(ethylene glycol) nanobeads by electrospraying

The present study describes the preparation and characterization of a novel nanocomposite, based on montmorillonite clay (MMT) encapsulation in poly(ethylene glycol) (PEG) by an electrospraying process. PEG/MMT nanocomposites with MMT contents ranging from 1 to 5 wt % were successfully prepared and characterized in relation to their morphological, spectroscopic, structural, and thermal properties. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy micrographs showed that the PEG nanobeads formed spherical shapes, and with increasing amount of MMT clay, the size of the beads decreased significantly, ranging from 120 to 3.7 nm. The Fourier transform infrared spectroscopy results suggested that there was no significant chemical interaction between PEG and MMT clay. However, the d‐spacing of MMT clay in PEG/MMT increased, a clear indication of the intercalation of PEG in the interlayer spaces of MMT clay. Furthermore, the thermal stability of PEG polymer decreased upon encapsulation of MMT clay in PEG/MMT composites. Nanoindentation results showed that the hardness and Young's modulus of the PEG/MMT composites increased with 3 wt % loading of MMT. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45048.     

Nanocomposites based on poly(butylene adipate‐co‐terephthalate) and montmorillonite

Nanocomposites based on biodegradable poly(butylene adipate‐co‐terephthalate) (PBAT) and layered silicates were prepared by the melt intercalation method. Nonmodified montmorillonite (MMT) and organo‐modified MMTs (DA‐M, ODA‐M, and LEA‐M) by the protonated ammonium cations of dodecylamine, octadecylamine, and N‐lauryldiethanolamine, respectively, were used as the layered silicates. The comparison of interlayer spacing between clay and PBAT composites with inorganic content 3 wt % measured by X‐ray diffraction (XRD) revealed the formation of intercalated nanocomposites in DA‐M and LEA‐M. In case of PBAT/ODA‐M (3 wt %), no clear peak related to interlayer spacing was observed. From morphological studies using transmission electron microscopy, the ODA‐M was found to be finely and homogeneously dispersed in the matrix polymer, indicating the formation of exfoliated nanocomposite. When ODA‐M content was increased, the XRD peak related to intercalated clay increased. Although the exfoliated ODA‐M (3 wt %) nanocomposite showed a lower tensile modulus than the intercalated DA‐M and LEA‐M (3 wt %) composites, the PBAT/ODA‐M composite with inorganic content 5 wt % showed the highest tensile modulus, strength, and elongation at break among the PBAT composites with inorganic content 5 wt %. Their tensile properties are discussed in relation to the degree of crystallinity of the injection molded samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 386–392, 2005     

Synthesis of a Novel Zirconium Oligostyrenylphosphonate-Phosphate and its Application in Asymmetric Epoxidation

The layered crystalline zirconium oligostyrenylphosphonate-phosphate (LCZSPP) was synthesized in the presence of HF for the first time, and this compound was well characterized by FT-IR, TG, SEM, TEM, XPS and XRD. The LCZSPP possessed high thermal stability by TG. SEM and TEM demonstrated that this compound is a typically layered crystalline compound with basically regular shape. XRD data also showed that the interlayer spacing (10.65 Å) of the sample was 3.01 Å more than the α-ZrP (7.64 Å). Moreover, chiral Jacobsen’s catalyst was axially immobilized onto LCZSPP by a diamine linker group. All the synthesized heterogeneous catalysts exhibited excellent reactivity and enantioselectivity in the asymmetric epoxidation of simple olefins.     

Impact modified epoxy/montmorillonite nanocomposites: synthesis and characterization

Diglycidyl ether of bisphenol A type epoxy resin-polyether polyol-organically treated montmorillonite ternary nanocomposites were synthesized in this study. The effects of addition of polyether polyol as an impact modifier on morphological, thermal and mechanical properties of nanocomposites were investigated by X-ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry, impact and tensile testing. The results showed that organically treated montmorillonite is intercalated by epoxy, since the interlayer spacing expanded from 1.83 to 3.82 nm upon nanocomposite synthesis. The addition of polyether polyol impact modifier had no effect on the interlayer spacing. SEM examination showed that polyol forms an immiscible phase in the epoxy matrix. Thermal characterization of nanocomposites indicated an increase in T_g with respect to both polyether polyol and montmorillonite contents. The impact strength of the samples with no clay was improved approximately 160% upon adding 7 wt% polyether polyol. In polyether polyol modified nanocomposites, the impact and tensile strengths decreased with respect to increasing amount of montmorillonite and showed a maximum with respect to the polyether polyol content at constant clay loading. The Young's modulus of the nanocomposites exhibited an increase with respect to the montmorillonite loading and showed a maximum with respect to the polyol content at each clay loading.     

Nanocomposites of poly(trimethylene terephthalate) with organoclay

Two different kinds of clay were organomodified with cetylpyridinium chloride (CPC) as an intercalation agent. Poly(trimethylene terephthalate) (PTT)/organoclay nanocomposites were prepared by the solution intercalation method. Wide‐angle X‐ray diffraction (WAXD) indicated that the layers of clay were intercalated by CPC and the interlayer spacing was a function of the cationic exchange capacity (CEC) of the clay: the higher the CEC, the larger the interlayer spacing is. The WAXD studies showed that the interlayer spacing of organoclay in the nanocomposites depends on the amount of organoclay. From the results of differential scanning calorimetry analysis it was found that clay behaves as a nucleating agent and enhances the crystallization rate of PTT. The maximum enhancement of the crystallization rate for the nanocomposites was observed in nanocomposites containing about 5 wt % organoclay with a range of 1–15 wt %. The thermal stability of the nanocomposites was enhanced by the addition of 1–10 wt % organoclay as found from thermogravimetric analysis. The thermal stability of the PTT/organoclay nanocomposites was related to the organoclay content and the dispersion in the PTT matrix. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3315–3322, 2003     

蒙脱土结构和性质对催化不饱和脂肪酸二聚化反应的影响

钠基蒙脱土经过一次插层有机改性和二次插层有机改性后制得有机改性蒙脱土,作为催化剂用于催化不饱和脂肪酸二聚化反应制备二聚酸。采用XRD、SEM、TEM、FTIR和TG等检测手段对有机改性后蒙脱土的内层结构和性质进行分析。实验表明改性后蒙脱土层间距由1.48 nm扩大到3.82 nm,而且保持原来的夹心结构不变。蒙脱土的表面形貌和内部结构发生改变,表面变得疏松,内部层间距扩大且插层剂含量增加,分散实验表明二次插层有机改性蒙脱土在不饱和脂肪酸中分散性能优异。相同条件下,二次插层有机改性蒙脱土催化不饱和脂肪酸二聚化反应,二聚酸产率75.33%,是未改性蒙脱土催化制得二聚酸产率的2.14倍,并通过FTIR、¹H NMR和LC-MS证实合成的产物为二聚酸。     

Preparation and properties of styrene–butadiene rubber based nanocomposites: The influence of the structural and processing parameters

Rubber‐based nanocomposites were prepared with octadecyl amine modified sodium montmorillonite clay and styrene–butadiene rubber with different styrene contents (15, 23, and 40%). The solvent used to prepare the nanocomposites, the cure conditions, and the cure system were also varied to determine their effect on the properties of the nanocomposites. All the composites were characterized with X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The XRD studies revealed exfoliation for the modified clay–rubber composites. The TEM photomicrographs showed a uniform distribution of the modified clay in the rubber matrix. The thickness of the particles in the exfoliated composites was around 10–15 nm. Although the FTIR study of the unmodified and modified clays showed extra peaks due to the intercalation of the amine chains into the gallery, the spectra for the rubber–clay nanocomposites were almost the same because of the presence of a very small amount of clay in the rubber matrix. All the modified clay–rubber nanocomposites displayed improved mechanical strength. The styrene content of the rubber had a pronounced effect on the properties of the nanocomposites. With increasing styrene content, the improvement in the properties was greater. Dicumyl peroxide and sulfur cure systems displayed similar strength, but higher elongation and slightly lower modulus values were obtained with the sulfur cure system. The curing of the samples at four different durations at 160°C showed that the cure time affected the properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 698–709, 2004     

Poly(3‐hydroxybutyrate)–thermoplastic starch–organoclay bionanocomposites: Surface properties

Bionanocomposites based on poly(3‐hydroxybutyrate) (PHB) and starch plasticized with glycerol and water [thermoplastic starch (TPS)] with organically modified montmorillonite clay as a nanofiller were obtained by melt‐blending. The influence of the clay and TPS on the thermal and mechanical properties of the resultant bionanocomposite was investigated by various techniques, such as X‐ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM), thermogravimetric analysis, differential scanning calorimetry, and nanoindentation. The results obtained by AFM showed that bionanocomposites have a surface roughness of 30.88 nm, compared to 14.53 nm for processed PHB. This result is obtained due to the migration of clay layers to the surface. From XRD and TEM it was determined that the clay layers of the bionanocomposites are completely separated. The hardness and elastic moduli of bionanocomposites have values similar to those of PHB, improving the drawbacks of the PHB–TPS blends (65:35 weight ratio). The thermal properties do not present significant changes, and only the degree of crystallinity decreased with increasing clay content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45217.