Studies of particle dispersion in plasticized poly(vinyl chloride)/montmorillonite nanocomposites

Poly(vinyl chloride)(PVC) and dioctyl phthalate (DOP) were mixed with 5 and 10 wt % of Cloisite Na⁺, Cloisite 30B or Cloisite 93A. The obtained nanocomposites were characterized by thermal analysis using a thermogravimetric analyzer which showed that addition of 5 wt % of nanoclay to PVC increased its thermal stability in the sequence: Cloisite Na⁺< Cloisite 93A< Cloisite 30B. The electrical conductivity of these composites was studied as a function of temperatures and showed that the conductivity of PVC was enhanced upon using 5 wt % of nanoclay in the sequence: Cloisite Na⁺< Cloisite 30B < Cloisite 93A. The activation energy of interaction of PVC with nanoclay was found to be lowest for the composite containing 5 wt % of nanoclay in the same sequence. The tensile strength, elongation (%), and Young's modulus were considerably enhanced upon increasing the clay content to 5 wt % in the sequence: Cloisite Na⁺< Cloisite 93A < Cloisite 30B. X‐ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study these nanocomposite structures, and it was found that the organoclay layers are homogeneously dispersed in the PVC matrix when 5 wt % of Cloisite 30B or Cloisite 93A was used. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of hydrogen bonding on the rheology of polycarbonate/organoclay nanocomposites

The linear dynamic viscoelastic properties and non-linear transient rheology of polycarbonate (PC)/clay nanocomposites were investigated at temperatures ranging from 240 to 280 °C. For the study, nanocomposites of PC and natural montmorillonite (Cloisite Na⁺) or chemically modified clay (Cloisite 30B) were prepared by melt blending in a twin-screw extruder. Cloisite 30B is a natural montmorillonite modified with methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium chloride (MT2EtOH). In both PC/Cloisite Na⁺ and PC/Cloisite 30B nanocomposites the concentration of clay was varied from 2.3 to 4.3 wt%. In situ Fourier transform infrared (FTIR) spectroscopy results show that at temperatures ranging from 30 to 280 °C the carbonyl groups in PC and the hydroxyl groups in MT2EtOH of Cloisite 30B in PC/Cloisite 30B nanocomposites formed hydrogen bonds, while no evidence of hydrogen bonding was observed in the PC/Cloisite Na⁺ nanocomposites. There are no discernible sharp reflections in the X-ray diffraction (XRD) patterns of PC/Cloisite 30B nanocomposites, after Cloisite 30B having the d₀₀₁ spacing of 1.85 nm was mixed with PC, whereas the d₀₀₁ spacing changes little (1.17 nm) before and after the mixing of Cloisite Na⁺ to PC. Transmission electron microcopy (TEM) images show that organoclay platelets are well dispersed in PC/Cloisite 30B nanocomposites, while the untreated clay platelets are poorly dispersed in PC/Cloisite Na⁺ nanocomposites. The observed differences in XRD patterns and TEM images between the two nanocomposite systems are explained by in situ FTIR spectroscopy. The results of rheological measurements (linear dynamic viscoelasticity, non-linear transient shear flow, and steady-state shear flow) support the conclusions drawn from the results of XRD, TEM, and FTIR spectroscopy.     

Improving heat ageing and thermal properties of silicone rubber using montmorillonite clay

Heat ageing and thermal stability of a silicone rubber (SR) filled with montmorillonite clay (MMT) was investigated. Three types of rubber nanocomposites were prepared with highly exfoliated Cloisite 30B (SR/C30B), intercalated/exfoliated Cloisite Na⁺ (SR/Na⁺MMT), and highly intercalated Cloisite 20A (SR/C20A). This study showed that the SR/C30B nanocomposite exhibited excellent heat resistance in comparison to the other two nanocomposites and neat SR as revealed by higher retention strength. The thermal stability of the rubber in air was strongly dependent on the clay morphology and increased in the following order: highly intercalated/exfoliated SR/Na⁺MMT < highly intercalated SR/C20A < highly exfoliated SR/C30B. The thermogravimetric analyses of the SR/C30B nanocomposite showed a substantial increase in the final residue in comparison with the neat SR. This indicated a major improvement in the thermal stability of the rubber containing the exfoliated clay, which was also supported by the higher activation energy of decomposition measured for the nanocomposite. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41061.     

Effect of shear rate on structural,mechanical, and barrier properties of chitosan/montmorillonite nanocomposite film

The dispersion of MMT‐Na⁺ (montmorillonite) layers in a chitosan polymer matrix, using the homogenization, was performed. The effect of shear rate was characterized on the mechanical, barrier, and structural properties of nanocomposites. Elongation at break (EAB) was unaffected by shear rate, which decreased after homogenization, increased above 13,000 rpm, however, tensile strength (TS) dramatically increased up to 59 MPa at 16,000 rpm. Water vapor permeability (WVP) and oxygen permeability (OP) of the homogenized nanocomposite decreased more than that of untreated nanocomposite and OP was not significantly changed above 16,000 rpm of shear rate. XRD result and TEM images indicated that three types of tactoids, exfoliation, and intercalation were generated and the largest distance of 18.87 Å between MMT‐Na⁺ layers was produced at 16,000 rpm. The results indicate that homogenization was a beneficial method for effectively dispersing MMT‐Na⁺ layers in a chitosan polymer matrix and that a shear rate of 16,000 rpm was the effective condition. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and Properties of Biodegradable Thermoplastic Starch/Clay Hybrids

Biodegradable thermoplastic starch (TPS)/clay hybrids were prepared by melt intercalation. Three organically modified montmorillonite (MMT) with different ammonium cations and one unmodified Na⁺ MMT (Cloisite Na⁺) were used. Cloisite Na⁺ showed the best dispersion in the TPS matrix. It was observed that the TPS/Cloisite Na⁺ hybrid showed an intercalation of TPS in the silicate layer due to the matching of the surface polarity and interactions of the Cloisite Na⁺ and the TPS, which gives higher tensile strength and better barrier properties to water vapor as compared to the other TPS/organoclay hybrids as well as the pristine TPS. It was found that the dynamic mechanical properties of the TPS/clay hybrids were also affected by the polar interactions.     

Synthesis and dielectric properties of polystyrene‐clay nanocomposite materials

Polystyrene‐clay nanocomposite (PsCN) materials were synthesized and their properties of crystallinity, thermal behavior, and dielectric characteristics were investigated. A polymerizable cationic surfactant, [2‐(dimethylamino)ethyl]triphenylphonium bromide, was used for the intercalation of montmorillonite (MMT). The organophilic MMT was prepared by Na⁺‐exchanged MMT and ammonium cations of a cationic surfactant in an aqueous medium. Organophilic styrene monomers were intercalated into the interlayer regions of organophilic clay hosts followed by a free‐radical polymerization. Exfoliation to 2 wt % MMT in the polystyrene (PS) matrix was achieved as revealed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal properties by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were also studied. The dielectric properties of PsCNs in the form of film with clay loading from 1.0 to 5.0 wt % were measured under frequencies of 100 Hz–1 MHz at 25–70°C. A decreased dielectric constant and low dielectric loss were observed for PsCN materials. The dielectric response at low frequency that originated from dipole orientation was suppressed due to the intercalation of clay materials. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1368–1373, 2004     

Synthesis and characterization of epoxy based nanocomposites

Epoxy‐clay nanocomposites were synthesized to examine the effects of the content and type of different clays on the structure and mechanical properties of the nanocomposites. Diglycidyl ether of bisphenol‐A (epoxy) was reinforced by 0.5–11 wt % natural (Cloisite Na⁺) and organically modified (Cloisite 30B) types of montmorillonite. SEM results showed that as the clay content increased, larger agglomerates of clay were present. Nanocomposites with Cloisite 30B exhibited better dispersion and a lower degree of agglomeration than nanocomposites with Cloisite Na⁺. X‐ray results indicated that in nanocomposites with 3 wt % Cloisite 30B, d‐spacing expanded from 18.4 Å (the initial value of the pure clay) to 38.2 Å. The glass transition temperature increased from 73°C, in the unfilled epoxy resin, to 83.5°C in the nanocomposite with 9 wt % Cloisite 30B. The tensile strength exhibited a maximum at 1 wt % modified clay loading. Addition of 0.5 wt % organically modified clay improved the impact strength of the epoxy resin by 137%; in contrast, addition of 0.5 wt % unmodified clay improved the impact strength by 72%. Tensile modulus increased with increasing clay loading in both types of nanocomposites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1081–1086, 2005     

Colorless polyimide nanocomposite films with pristine clay: Thermal behavior,mechanical property,morphology, and optical transparency

Polyimide (PI)/clay hybrids were synthesized using the in situ solution intercalation method via poly(amic acid). The Na ion‐exchanged clays Na⁺‐saponite (SPT), Na⁺‐mica (Mica), and Na⁺‐montmorillonite (MMT) were used for the intercalation of PI polymer chains. Our dispersion results show that pristine SPT is more easily dispersed in a PI matrix than MMT or Mica. PI nanocomposites were prepared with various SPT contents to examine the variations with SPT content in the range 0–1 wt% of the thermomechanical properties, morphology, and optical transparency of the nanocomposites. The PI films have excellent optical transparencies, and are almost colorless. However, the optical transparency of the PI hybrid films decreases slightly with increases in the clay content. We also examined the relationship between the properties and clay content of the PI hybrid films using wide‐angle X‐ray diffraction (XRD) measurements, electronic microscopy (SEM and TEM), and universal tensile machine (UTM). The color intensities of the PI films were evaluated with a spectrophotometer. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Electrical conductivity behavior of epoxy matrix nanocomposites with simultaneous dispersion of carbon nanotubes and clays

In this work, nanocomposites with simultaneous dispersion of multiwalled carbon nanotubes (MWCNT) and montmorillonite clays in an epoxy matrix were prepared by in situ polymerization. A high energy sonication was employed as the dispersion method, without the aid of solvents in the process. The simultaneous dispersion of clays with carbon nanotubes (CNT) in different polymeric matrices has shown a synergic potential of increasing mechanical properties and electrical conductivity. Two different montmorillonite clays were used: a natural (MMT‐Na⁺) and an organoclay (MMT‐30B). The nanocomposites had their electrical conductivity (σ) and dielectric constant (ε_r) measured by impedance spectroscopy. The sharp increase in electrical conductivity was found between 0.10 and 0.25 wt% of the MWCNTs. Transmission electron microscopy (TEM) of the samples showed a lower tendency of MWCNT segregation on the MMT‐30B clay surface, which is connected to intercalation/exfoliation in the matrix, that generates less free volume available for MWCNTs in the epoxy matrix. Data from electrical measurement showed that simultaneously adding organoclay reduces the electrical conduction in the nanocomposite. Moreover, conductivity and permittivity dispersion in low frequency suggest agglomeration of nanotubes surrounding the natural clay (MMT‐Na⁺) particles, which is confirmed by TEM. POLYM. COMPOS., 37:1603–1611, 2016. © 2014 Society of Plastics Engineers     

Dispersion of chiral amino acid organomodified Cloisite Na in poly(vinyl alcohol) matrix for designing of novel bionanocomposite films

In this study the inorganic nanolayers of Cloisite Na⁺ was modified with ammonium salt of l-valine amino acid (Val) and then it was dispersed in poly(vinyl alcohol) (PVA) matrix. The PVA/Cloisite Na⁺/Val bionanocomposites (BNC)s were prepared by solution intercalation technique using ultrasonic irradiation. The reaction between this novel organically modified Cloisite Na⁺ and PVA occurred by the hydrogen bonding and hydrophobic interactions. The basal spacing of the Cloisite Na⁺/Val was studied by X-ray diffraction. The thermal stability and optical clarity of PVA and PVA/Cloisite Na⁺/Val are also studied by thermogravimetric analysis (TGA) and UV–visible transmission spectra, respectively. TGA results show that using Cloisite Na⁺/Val in the PVA matrix improved the thermal stability property of the resulting BNC films. The morphological image of synthesized materials was studied by scanning electron microscopy, and transmission electron microscopy. The nanocomposite structure study specified a coexistence of exfoliated and intercalated Cloisite Na⁺/Val layers in the PVA matrix.     

Mechanical properties of layered silicate/starch polycaprolactone blend nanocomposites

The mechanical behavior of layered silicate/starch polycaprolactone blend nanocomposites was evaluated. Three different clays (Cloisite Na⁺, Cloisite 30B and Cloisite 10A) were used as reinforcement. Nanocomposites were prepared by melt intercalation followed by compression molding. These nanocomposites were characterized using X‐ray diffraction, scanning electron microscopy, dynamic mechanical analysis and tensile testing. X‐ray diffraction results showed that most of the clays were intercalated within the polymeric chains. In all cases, mechanical properties were improved with clay incorporation and the improvement was better as the clay content was increased. The best properties were achieved with Cloisite 10A due to their greatest compatibility with the matrix. A mechanical model, which takes into account the effective parameters of the clay, was used in order to estimate the dispersion of clay within the polymer. The highest dispersion was obtained for Cloisite 10A, which is in accordance with the experimental mechanical properties. Although dynamical‐mechanical properties improved with clay incorporation, the glass transition temperature was not affected. Copyright © 2006 Society of Chemical Industry     

Preparation and characterization of elastomer‐based nanocomposite gels using an unique latex blending technique

Nanocomposite (NC) gels based on natural rubber (NR) and styrene butadiene rubber (SBR) were prepared by using a unique latex blending technique. These NC gels were prepared by first blending the water swollen unmodified montmorillonite clay (Na⁺‐MMT) suspension into the respective latices followed by prevulcanization to generate crosslinked nanogels. Use of water assisted fully delaminated Na⁺‐MMT suspension resulted in predominantly exfoliated morphology in the NC gels, as revealed by X‐ray diffraction study and transmission electron microscopy. Addition of Na⁺‐MMT significantly improved various physical, mechanical and thermal properties of these NC gels. For example, 6 phr of Na⁺‐MMT loaded NR based NC gels registered 54% and 200% increase in tensile strength and Young's modulus, respectively, compared to the unfilled NR gels. SBR based NC gels also showed similar level of improvement in mechanical properties. Mechanical properties of NC gels prepared using this route were also compared with the NC gels prepared by co‐coagulation and conventional curing technique and found to be superior. In the case of dynamic mechanical properties, NC gels showed higher glass transition temperatures along with a concomitant increase in storage moduli, compared to the unfilled gels. These Na⁺‐MMT reinforced NC gels also exhibited markedly improved thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Morphology and Thermal Stability of Novolac Phenolic Resin/Clay Nanocomposites Prepared via Solution High‐Shear Mixing

Phenolic resin/clay composites were prepared by high‐shear mixing of clay suspended in CH₃OH solutions of Novolac resin and curing agent. Pure clay Cloisite Na⁺ and pillared clays Cloisite 10A, 30B, and Na⁺Cloisite that was pillared by 3‐hexadecyl‐1‐methylimidazolium bromide were studied. After CH₃OH evaporation, Novolac was cured at low temperatures. XRD showed that clay gallery d‐spacings decreased upon solvent evaporation and partial curing. Slight d‐spacing increases were sometimes observed from a partially cured stage to a further cured composite. Na⁺Cloisite gave the highest nanodispersion, Cloisites 10A and 30B the lowest. TGA revealed that Na⁺ clay or organoclay incorporation in partially cured and cured composites did not improve the thermal stability of Novolac.

     

Preparation and characterization of high performance exfoliated montmorillonite/silicone rubber nanocomposites with enhanced mechanical properties

Highly exfoliated and intercalated silicone rubber (SR) nanocomposites based on natural montmorillonite (Cloisite Na⁺) and organically modified montmorillonite (Cloisite 30B and Cloisite 20A) were successfully prepared by melt‐mixing technique. Dispersion of the nanoclays in the rubber nanocomposites was subsequently investigated. As indicated by the X‐ray diffraction (XRD) analysis, intercalation, and exfoliation of the clay particles in the nanocomposites was achieved at less than 8 parts per hundred (phr) rubber by weight, irrespective of the initial interlayer spacing of the nanoclay particles. Both Cloisite Na⁺ and Cloisite 30B were spontaneously transformed into exfoliated microstructures during the vulcanisation stage. Overall, the use of the nanoclays in silicone rubber improved the Young's modulus, tensile strength, and elongation at break by more than 50% as compared with the control rubber. In addition, this work provided a fresh insight into the way intercalated and exfoliated morphologies affect mechanical properties of silicone rubber nanocomposites. It was shown that the exfoliated Cloisite Na⁺ yielded outstanding mechanical properties with low hysteresis at the same loading of the exfoliated Cloisite 30B and intercalated Cloisite 20A organoclays. As expected, the formation of crosslinks affected the mechanical properties of the rubber vulcanizate significantly. POLYM. ENG. SCI., 53:2603–2614, 2013. © 2013 Society of Plastics Engineers     

Novel polyether polyurethane/clay nanocomposites synthesized with organicly modified montmorillonite as chain extenders

A kind of novel polyether polyurethane (PU)/clay nanocomposite was synthesized using poly(tetramethylene glycol), 4,4′‐diphenylmethane diisocyanate (MDI), 1,6‐hexamethylenediamine, and modified Na⁺‐montmorillonite (MMT). Here, organicly modified MMT (O‐MMT) was formed by applying 1,6‐hexamethylenediamine as a swelling agent to treat the Na⁺‐MMT. The X‐ray analysis showed that exfoliation occurred for the higher O‐MMT content (40 wt %) in the polymer matrix. The mechanical analysis indicated that, when the O‐MMT was used as a chain extender to replace a part of the 1,2‐diaminopropane to form PU/clay nanocomposites, the strength and strain at break of the polymer was enhanced when increasing the content of O‐MMT in the matrix. When the O‐MMT content reached about 5%, the tensile strength and elongation at break were over 2 times that of the pure PU. The thermal stability and the glass transition of the O‐MMT/PU nanocomposites also increased with increasing O‐MMT content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 6–13, 2006     

Melt-compounded salt-containing poly(ethylene oxide)/clay nanocomposites for polymer electrolyte membranes

The present study demonstrates the use of a simple and versatile melt-compounding route to prepare NaClO₄-containing poly(ethylene oxide) PEO/clay nanocomposites combining excellent mechanical properties with a competitive level of the ionic conductivity. The nanostructure and the resulting thermal, mechanical and conductive properties of the salt-containing PEO/clay nanocomposites were found to be highly sensitive to the clay type, i.e. aspect ratio of the clay, to the presence of an organic modifier in the intergallery spacing, and to the salt concentration. The highest increase of the shear storage modulus is obtained in the presence of single silicate layers, thus an exfoliated nanostructure, having a high aspect ratio. These structures are only obtained with an (polar) organically modified clay (Cloisite 30B), regardless of the presence of salt. The use of non-organically modified clays (Cloisite Na⁺ and Laponite) resulted in intercalated nanocomposites, with only a minor improvement in stiffness. A strong interaction between the Na⁺ from NaClO₄ and the Cloisite 30B silicate layers might be responsible for an increased PEO crystallinity and resultant additional increase in stiffness. A mechanism is proposed whereby the Na⁺ ions are drawn away from the PEO phase, to be complexed by the silicate layers, or even ion-exchanged with modifier cations. The addition of clay did not greatly affect the ion conductivity below the melt temperature of PEO. At higher temperatures, the nanocomposites displayed only slightly lower conductivities compared to the PEO/NaClO₄ complex, due to the presence of the clay platelets.     

Poly(vinyl alcohol) nanocomposites with different clays: Pristine clays and organoclays

Poly(vinyl alcohol) (PVA)/clay nanocomposites were synthesized using the solution intercalation method. Na ion‐exchanged clays [Na⁺–saponite (SPT) and Na⁺–montmorillonite (MMT)] and alkyl ammonium ion‐exchanged clays (C₁₂–MMT and C₁₂OOH–MMT) were used for the PVA nanocomposites. From the morphological studies, the Na ion‐exchanged clay is more easily dispersed in a PVA matrix than is the alkyl ammonium ion‐exchanged clay. Attempts were also made to improve both the thermal stabilities and the tensile properties of PVA/clay nanocomposite films, and it was found that the addition of only a small amount of clay was sufficient for that purpose. Both the ultimate tensile strength and the initial modulus for the nanocomposites increased gradually with clay loading up to 8 wt %. In C₁₂OOH–MMT, the maximum enhancement of the ultimate tensile strength and the initial modulus for the nanocomposites was observed for blends containing 6 wt % organoclay. Na ion‐exchanged clays have higher tensile strengths than those of organic alkyl‐exchanged clays in PVA nanocomposites films. On the other hand, organic alkyl‐exchanged clays have initial moduli that are better than those of Na ion‐exchanged clays. Overall, the content of clay particles in the polymer matrix affect both the thermal stability and the tensile properties of the polymer/clay nanocomposites. However, a change in thermal stability with clay was not significant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3208–3214, 2003     

Effects of acid neutralization on the morphology and properties of organoclay nanocomposites formed from K+ and Na+ poly(ethylene-co-methacrylic acid) ionomers

Nanocomposites were prepared by melt blending various sodium (Na⁺) and potassium (K⁺) ionomers formed from poly(ethylene-co-methacrylic acid) and the M₂(HT)₂ organoclay formed from montmorillonite (MMT). The effects of the neutralization level of the acid groups and the precursor melt index on the morphology and properties of the nanocomposites were evaluated using stress-strain analysis, wide angle X-ray scattering (WAXS), and transmission electron microscopy (TEM) coupled with particle analysis. The aspect ratio generally increases as the neutralization level increases, except for Na⁺ ionomer nanocomposites with neutralization levels >50%. It appears from both WAXS and TEM analyses that Na⁺ ionomer nanocomposites have higher levels of MMT exfoliation and particle orientation in the flow direction than K⁺ ionomer nanocomposites. DSC results indicate that the level of crystallinity in the Na⁺ ionomers generally increases slightly with MMT addition, while the crystallinity in the K⁺ ionomers decreases slightly with MMT addition. The relative modulus of K⁺ ionomer nanocomposites increases as the degree of neutralization increases. The relative moduli of Na⁺ ionomer nanocomposites are higher than the relative modulus of K⁺ ionomer nanocomposites, likely due to the increased crystallinity of the Na⁺ ionomers and the decreased crystallinity of the K⁺ ionomers upon addition of MMT, the higher exfoliation levels measured by the aspect ratios and the particle densities, and the higher particle orientation indicated by TEM and WAXS. The relative modulus generally increases as the aspect ratio increases. The elongation at break generally decreases as the MMT content increases and as the neutralization level increases for both ionomer types. The fracture energy of most of the ionomers increases with the addition of MMT, reaches a maximum between 2.5 and 5 wt% MMT, and then decreases upon further MMT addition.     

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     

Biomodification of cloisite Na+ with L‐methionine amino acid and preparation of poly(vinyl alcohol)/organoclay nanocomposite films

Polymer/layered‐silicate hybrids nanocomposites have attracted strong interest in today's materials research, as it is possible to achieve impressive enhancements of material properties compared to the pure polymers. In the present investigation, at first, Cloisite Na⁺ was modified by protonated form of natural L ‐methionine amino acid via ion‐exchange reaction to created chiral organonanoclay. Gallery spacing, interlamellar structure, and thermal stability of this novel chiral organonanoclay have been characterized using different techniques. Then it was used to fabrication of poly(vinyl alcohol) (PVA)/organonanoclay nanocomposite films (NCF)s with various compositions using solution casting method by ultrasound‐assisted method. The films were characterized using Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), scanning electronic microscopy, and transmission electronic microscopy (TEM). Furthermore, thermal and optical clarity properties were investigated by thermogravimetric analysis and UV–visible transmission spectra, respectively. The TEM and XRD structure study revealed a coexistence of exfoliated and intercalated organonanoclay in the PVA matrix. The addition of organoclay into the PVA origins increases in the thermal decomposition temperatures of the NCFs. This enhancement in the thermal stability is owing to the presence of organonanoclay, which act as barriers to maximize the heat insulation and to minimize the permeability of volatile degradation products to the material. At the same time, the optical clarity of PVA/organonanoclay NCFs is not decreased in comparison with that of pure PVA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012