Investigation of nanostructure and properties of aromatic–aliphatic polyamide‐based nanocomposites with clay additives

Aromatic–aliphatic polyamide/clay nanocomposites were produced using solution intercalation technique. Surface modification of the clay was performed with ammonium salt of aromatic diamine and the polyamide chains were produced by condensation of 4‐aminophenyl sulfone with sebacoyl chloride (SCC) in dimethyl acetamide. Carbonyl chloride endcapped polymer chains were prepared by adding extra SCC near the end of polymerization reaction. The nanocomposites were investigated for organoclay dispersion, water absorption, mechanical, and thermal properties. Formation of delaminated and intercalated nanostructures was confirmed by X‐ray diffraction and TEM studies. Tensile strength and modulus improved for nanocomposites with optimum organoclay content (8 wt %). Thermal stability and glass transition temperatures of nanocomposites increased relative to pristine polyamide with augmenting organoclay content. The amount of water uptake for these materials decreased as compared with the neat polyamide. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Transparent copolyester/organoclay nanocomposites prepared by in situ intercalation polymerization: Synthesis,characterization, and properties

In this study, amorphous poly(ethylene terephthalate‐co‐1,3/1,4‐cyclohexylenedimethylene terephthalate) (PETG)/organoclay nanocomposites was synthesized by the in situ intercalation polymerization of terephthalic acid, ethylene glycol, 1,3/1,4‐cyclohexanedimethanol, and organoclay. The organoclay was obtained by modifying sodium montmorillonite (clay) with hexadecyl triphenylphosphonium bromide. The thermal, mechanical, optical, and gas barrier properties of these PETG nanocomposites with various organoclay contents (0–3 wt%) were discussed. The differential scanning calorimetry and X‐ray analyses revealed that all of the nanocomposites were amorphous. X‐ray diffraction and transmission electron micrographs showed that the organoclay was well dispersed in the polymer matrix, although some parts of the agglomerated layers remained on the scale of several hundreds of nanometers. The thermal stability and the mechanical property of the nanocomposites increased with organoclay content. The optical transmittances of nanocomposites that contained 0.5, 1, and 3 wt% of organoclay were 86.8%, 84.4%, and 77.4%, respectively. The oxygen transmission rate of the nanocomposite that contained 3 wt% of organoclay was about 50% of the PETG base polymer. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Synthesis and characterization of poly(ethylene terephthalate) nanocomposites with organoclay

Poly(ethylene terephthalate) (PET)/montmorillonite (MMT) nanocomposites were prepared by solution intercalation method. The clay was organo‐modified with the intercalation agent cetylpyridinium chloride (CPC). Wide‐angle X‐ray diffraction (XRD) showed that the layers of MMT were intercalated by CPC. Four nanocomposites with organoclay contents of 1, 5, 10, and 15 wt % were prepared by solution blending. XRD showed that the interlayer spacing of organoclay in the nanocomposites depends on the amount of organoclay present. According to the results of differential scanning calorimetry (DSC) analysis, clay behaves as a nucleating agent and enhances the crystallization rate of PET. The maximum enhancement of crystallization rate for the nanocomposites was observed in those containing about 10 wt % organoclay within the studied range of 1–15 wt %. From thermogravimetric analysis (TGA), we found that the thermal stability of the nanocomposites was enhanced by the addition of 1–15 wt % organoclay. These nanocomposites showed high levels of dispersion without agglomeration of particles at low organoclay content (5 wt %). An agglomerated structure did form in the PET matrix at 15 wt % organoclay. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 140–145, 2004     

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     

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     

Use of purified and modified bentonites in linear low‐density polyethylene/organoclay/compatibilizer nanocomposites

Polyethylene‐based ternary nanocomposites were prepared with different clay structures, obtained by the modification of purified Resadiye bentonite as the reinforcement, a random terpolymer of ethylene, butyl acrylate, and maleic anhydride with the trade name Lotader3210 as the compatibilizer, and linear low‐density polyethylene (LLDPE) as the polymer matrix in an intensive batch mixer. The quaternary ammonium/phosphonium salts used for the modification of bentonite were dimethyldioctadecyl ammonium (DMDA) chloride (Cl), tetrakisdecyl ammonium (TKA) bromide (Br), and tributylhexadecyl phosphonium (TBHP) Br. The effects of the physical properties and structure of the organoclay on the clay dispersion were studied at different clay contents (2 and 5 wt %) and at a compatibilizer/organoclay ratio of 2.5. The extent of organoclay dispersion was determined by X‐ray diffraction (XRD) and was verified by transmission electron microscopy (TEM), mechanical testing, and rheological analysis. XRD analysis showed that the nanocomposite with the organoclay DMDA contained intercalated silicate layers, as also verified by TEM. The TEM analysis of the nanocomposites with TBHP exhibited intercalated/partially exfoliated clay dispersion. TKA, with a crowded alkyl environment, sheltered and hindered the intercalation of polymer chains through the silicate layers. In comparison to pure LLDPE, nanocomposites with a 33–41% higher Young's modulus, 16–9% higher tensile strength, and 75–144% higher elongation at break were produced with DMDA and TBHP, respectively (at 5 wt % organoclay). The storage modulus increased by 807–1393%, and the dynamic viscosity increased by 196–339% with respect to pure LLDPE at low frequencies for the samples with DMDA and TBHP (at 5 wt % organoclay). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Poly(butylene terephthalate)/Clay Nanocomposites directly Prepared from Pristine Montmorillonite (MMT)

Summary Poly(butylene terephthalate) (PBT)/clay nanocomposites have been prepared by melt intercalation method directly from pristine montmorillonite (MMT), using cetyl pyridinium chloride (CPC) as the polymer/clay reactive compatibilizer. The effect of the reactive compatibilizer (CPC) proportion relative to the clay on the structure and properties of the PBT/clay nanocomposites was studied by XRD, TEM, TGA and cone calorimeter. The results show that such appropriate proportion as 1 wt % CPC to 3 wt % MMT induces well-dispersed intercalated morphology and better thermal and flame retarded properties. At last the intercalation mechanism of the technology was discussed.     

Effect of nanofillers as reinforcement agents for lignin composite fibers

Biobased nanocomposites and composite fibers were prepared from organosolv lignin/organoclay mixtures by mechanical mixing and subsequent melt intercalation. Two organically‐modified montmorillonite (MMT) clays with different ammonium cations were used. The effect of organoclay varying from 1 to 10 wt % on the mechanical and thermal properties of the nanocomposites was studied. Thermal analysis revealed an increased in T_g for the nanocomposites as compared with the original organosolv lignin. For both organoclays, lignin intercalation into the silicate layers was observed using X‐ray diffraction (XRD). The intercalated hybrids exhibited a substantial increase in tensile strength and melt processability. In the case of organoclay Cloisite 30B, X‐ray analysis indicates the possibility of complete exfoliation at 1 wt % organoclay loading. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

New aramid‐based nanocomposites: Synthesis and characterization

New type of nanocomposites containing various proportions of montmorillonite in aromatic polyamide was prepared via solution intercalation method. Aramid chains were synthesized by reacting 4,4′‐oxydianiline with isophthaloyl chloride in N,N′‐dimethyl acetamide. Dodecylamine was used as swelling agent to change the hydrophilic nature of montmorillonite into organophilic. Appropriate amounts of organoclay were mixed in the polymer solution using high‐speed mixer for complete dispersion of the clay. Thin films cast from these materials after evaporating the solvent were characterized by XRD, TEM, mechanical, thermal, and water absorption measurements. The structure and morphology of the nanocomposites determined by XRD and TEM revealed the formation of exfoliated and intercalated clay platelets in the aramid matrix. Mechanical data indicated improvement in the tensile strength and modulus of the nanocomposites with clay loading up to 6 wt%. The glass transition temperature increased up to 12 wt% clay content and thermal stability amplified with increasing clay loading. The water absorption reduced gradually as a function of organoclay and approached to zero with 20 wt% organoclay in the aramid. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Preparation and characterization of poly(hydroxybutyrate‐co‐hydroxyvalerate)–organoclay nanocomposites

This study describes the microstructure and thermal and mechanical properties of poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHB/HV)–organoclay nanocomposites prepared by melt intercalation using Cloisite 30B, a monotallow bis‐hydroxyethyl ammonium‐modified montmorillonite clay. X‐ray diffractometry and transmission electron microscopy analyses clearly confirm that an intercalated microstructure is formed and finely distributed in the PHB/HV copolymer matrix because PHB/HV has a strong hydrogen bond interaction with the hydroxyl group in the organic modifier of Cloisite 30B. The nanodispersed organoclay also acts a nucleating agent, increasing the temperature and rate of crystallization of PHB/HV; therefore, the thermal stability and tensile properties of the organoclay‐based nanocomposites are enhanced. These results confirm that the organoclay nanocomposite greatly improves the material properties of PHB/HV. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 525–529, 2003     

Effect of blending sequence on the morphologies of poly(butylene terephthalate)/epoxy/clay nanocomposites by a rheological approach

Epoxy resin was used as a compatilizer to prepare poly(butylene terephthalate)/clay nanocomposites via melt intercalation. Three different mixing sequences were attempted in the present work: (1) to mix poly(butylene terephthalate) (PBT), epoxy, and organoclay in one step; (2) first to mix epoxy and organoclay, and then mix it with PBT; (3) to prepare PBT/organoclay hybrid first, and then mix it with epoxy to get the final nanocomposites. The results from X‐ray diffraction (XRD) reveal that all these hybrids present an intercalated structure. However, it can be observed that there are distinct differences in the amount and average size of clay tactoids dispersed in those hybrids from the transmission electron microscope (TEM) photographs, which are further confirmed successfully by the rheological measurements. On the basis of the strain overshoot intensity and the low‐frequency solid‐like response level in the small amplitude oscillatory shear (SAOS) measurements, it can be concluded that the blending sequence (2) is the best way to obtain a nice dispersion of clay in the matrix, forming a percolated tactoids network with highest density and intensity. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 340–346, 2006     

Synthesis and properties of polyimide (containing naphthalene) nanocomposites with organo‐modified montmorillonites

2,7‐Bis(4‐aminophenoxy) naphthalene (BAPN), a naphthalene‐containing diamine, was synthesized and polymerized with a 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) to obtain a polyimide (PI) via thermal imidization. To enhance the thermal and mechanical properties of the polymer, PI–Montmorillonite (MMT) nanocomposites were prepared from a DMAc solution of poly(amic acid) and a DMAc dispersion of MMT, which were organo‐modified with various amounts of n‐dodecylamine (DOA) or cetylpyridium chloride (CPC). FTIR, XRD, and TEM (transmission electron microscopy) were used to verify the incorporation of the modifying agents into the clay structure and the intercalation of the organoclay into the PI matrix. Results demonstrated that the introduction of a small amount of MMT (up to 5%) led to the improvement in thermal stability and mechanical properties of PI. The decomposition temperature of 5% weight loss (T_d,5%) in N₂ was increased by 46 and 36°C in comparison with pristine PI for the organoclay content of 5% with DOA and CPC, respectively. The nanocomposites were simultaneously strengthened and toughened. The dielectric constant, CTE, and water absorption were decreased. However, at higher organoclay contents (5–10%), these properties were reduced because the organoclay was poorly dispersed and resulted in aggregate formation. The effects of different organo‐modifiers on the properties of PI–MMT nanocomposite were also studied; the results showed that DOA was comparable with CPC. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Polystyrene nanocomposite materials by in situ polymerization into montmorillonite–vinyl monomer interlayers

A different series of new polystyrene–clay nanocomposites have been prepared by grafting polymerization of styrene with vinyl‐montmorillonite (MMT) clay. The synthesis was achieved through two steps. The first step is the modification of clay with the vinyl monomers, such as N,N‐dimethyl‐n‐octadecyl‐4‐vinylbenzyl‐ammonium chloride, n‐octadecyl‐4‐vinylbenzyl‐ammonium chloride, triphenyl‐4‐vinylbenzyl‐phosphonium chloride, and tri‐n‐butyl‐4‐vinylbenzyl‐phosphonium chloride. The second step is the polymerization of styrene with different ratios of vinyl‐MMT clay. The materials produced were characterized by different physical and chemical methods: (1) IR spectra, confirming the intercalation of the vinyl‐cation within the clay interlayers; (2) thermogravimetric analysis (TGA), showing higher thermal stability for PS–nanocomposites than polystyrene (PS) and higher thermal stability of nanocomposites with of phosphonium moieties than nanocomposites with ammonium moieties; (3) swelling measurements in different organic solvents, showing that the swelling degree in hydrophobic solvents increases as the clay ratio decreases; (4) X‐ray diffraction (XRD), illustrating that the nanocomposites were exfoliated at up to a 25 wt % of organoclay content; and (5) scanning electron microscopy (SEM), showing a complete dispersion of PS into clay galleries. Also, transmission electron microscopy (TEM) showed nanosize spherical particles of ～ 150–400 nm appearing in the images. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3739–3750, 2007     

Morphology and mechanical properties of heterophasic PP–EP/EVA/organoclay nanocomposites

The effect of vinyl acetat (VA) on the morphological, thermal stability, and mechanical properties of heterophasic polypropylene–(ethylene‐propylene) copolymer (PP–EP)/poly(ethylene vinyl acetate) (EVA)/organoclay nanocomposites was studied. Tailored organoclay C20A was selected to enhance the exfoliation of the clay platelets. Depending on the VA content, there were two morphological organoclay populations in the systems. Both populations were directly observed by scanning transmission electron microscopy and measured by wide‐angle X‐ray diffraction and small‐angle X‐ray scattering. The content of VA in EVA originated spherical and elongated morphologies in the resultant nanocomposites. High‐VA content led to a better intercalation of the organoclay platelets. Measurement of thermal properties suggested that higher VA decreases thermal stability in samples both with and without organoclay, although nanocomposites had higher thermal stability than samples without clay. The storage modulus increased both with nanoclay and VA content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Poly(ethylene‐vinyl co‐vinyl acetate)/clay nanocomposites: Mechanical,morphology, and thermal behavior

Nanocomposites of ethylene‐vinyl acetate copolymer (EVAL) with Dellite organoclay were prepared in a laboratory extruder. The extent of intercalation of the nanocomposites was studied by field emission scanning electron microscopy and X‐ray diffraction. It was established that the organoclay is well dispersed and preferentially embedded in the EVAL phase. Further, the intercalation degree of the organoclay decreased with increasing organoclay content. The mechanical properties of the nanocomposites were studied as a function of clay loading and EVAL type. The nanocomposites exhibited enhanced thermal stability as seen in thermogravimetric studies. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Photopolymerization and characteristics of reactive organoclay–polyurethane nanocomposites

Polymerizable ammonium surfactants with two methacrylate alkyl chains were successfully synthesized via Michael‐Addition and quaternization reaction. Organoclays containing reactive methacrylate groups were prepared by cationic exchange process. Intercalated nanocomposites have been produced by UV initiated polymerization with different organophilic clay loading. X‐ray diffraction (XRD) spectroscopy showed that the d spacing of organoclay increased with increment of methacrylate alkyl chains length. When organoclay were dispersed in urethane acrylate resin, and photopolymerized, the d spacing increased, but the increasing extent decreased with increment of the methacrylate alky chains length. Thermogravimetric analysis indicated that incorporation of reactive organoclay had better thermal stablity than cetyltrimethylammonium bromide (CTMA)‐modified organoclay and dynamic mechanical analysis (DMA) showed nanocomposites containing reactive organoclay had high glass transition temperature and storage modulus. Tensile analysis implied that incorporation of reactive organoclay could enhance mechanical and tensile properties dramatically. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Morphology,Thermal and Mechanical Properties of Poly (Styrene-Acrylonitrile) (SAN)/Clay Nanocomposites from Organic-Modified Montmorillonite

Poly (styrene-acrylonitrile) (SAN)/clay nanocomposites have successfully been prepared by melt intercalation method. The hexadecyl triphenyl phosphonium bromide (P16) and cetyl pyridium chloride (CPC) are used to modify the montmorillonite (MMT). The structure and thermal stability property of the organic modified MMT are, respectively characterized by Fourier transfer infrared (FT-IR) spectra, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results indicate that the cationic surfactants intercalate into the gallery of MMT and the organic-modified MMT by P16 and CPC has higher thermal stability than hexadecyl trimethyl ammonium bromide (C16) modified MMT. The influences of the different organic modified MMT on the structure and properties of the SAN/clay nanocomposites are investigated by XRD, transmission electronic microscopy (TEM), high-resolution electron microscopy (HREM), TGA and dynamic mechanical analysis (DMA), respectively. The results indicate that the SAN cannot intercalate into the interlayers of the pristine MMT and results in microcomposites. However, the dispersion of the organic-modified MMT in the SAN is rather facile and the SAN nanocomposites reveal an intermediate morphology, an intercalated structure with some exfoliation and the presence of small tactoids. The thermal stability and the char residue at 700°C of the SAN/clay nanocomposites have remarkably enhancements compared with pure SAN. DMA measurements show that the silicate clays improve the storage modulus and glass transition temperature (Tg) of the SAN matrix in the nanocomposites.     

Poly(butylene terephthalate)–clay nanocomposites prepared by melt intercalation: morphology and thermomechanical properties

Nanocomposites based on poly(butylene terephthalate) (PBT) and an organoclay (Cloisite 30B) were prepared by melt blending using a twin‐screw extruder. Two kinds of PBTs, ie PBT‐A and PBT‐B, with different inherent viscosities (η_inh), were used for this study (η_inh of PBT‐A and PBT‐B were 0.74 and 1.48, respectively). Dispersion of the clay layers in the PBT nanocomposites was characterized by using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile and dynamic mechanical properties and non‐isothermal crystallization temperatures of the nanocomposites were also examined. Nanocomposites based on the higher‐viscosity PBT (PBT‐B) showed a higher degree of exfoliation of the clay and a higher reinforcing effect when compared to the composites based on the lower‐viscosity PBT (PBT‐A). The clay nanolayers dispersed in PBT matrices lead to increases in the non‐isothermal crystallization temperatures of the PBTs, with such increases being more significant for the PBT‐B nanocomposites than for the PBT‐A nanoocomposites. Copyright © 2004 Society of Chemical Industry     

Polystyrene–organoclay nanocomposites prepared by melt intercalation,in situ,and masterbatch methods

In this study, polystyrene (PS)/montmorillonite nanocomposites were prepared by melt intercalation, in situ polymerization, and masterbatch methods. In the masterbatch method, as the first step, a high clay content composite of PS–organoclay (masterbatch) was prepared by in situ polymerization, and then the prepared masterbatch was diluted to desired compositions with commercial PS in a twin‐screw extruder. The structure and mechanical properties of the nanocomposites were examined. X‐ray diffraction (XRD) analysis showed that the d‐spacing of the in situ formed nanocomposites increased from 32.9 Å for the organoclay powder to 36.3 and 36.8 Å respectively in nanocomposites containing 0.73 and 1.6 wt% organoclay, indicating intercalation. However, the d‐spacing of the other prepared materials remained nearly unchanged when compared with pure organoclay powder. Thus, at these low clay contents, in situ formed nanocomposites showed the best improvement in mechanical properties including tensile, impact strength, and Young's modulus. In situ polymerization method did not prove to be efficient at high clay loadings in terms of intercalation and mechanical properties. At high clay loadings, the effects of the three methods in promoting mechanical properties were not significantly different from each other. POLYM. COMPOS., 27:249–255, 2006. © 2006 Society of Plastics Engineers     

Preparation of polyethylene–clay nanocomposites directly from Na+ montmorillonite by a melt intercalation method

Polyethylene (PE)/clay nanocomposites were prepared directly from Na⁺ montmorillonite by a melt intercalation technique, using hexadecyl trimethyl ammonium bromide (C16) as a reactive compatibilizer. Three other polymer–clay nanocomposites were also prepared by this new technique. Their structures were characterized by X‐ray diffraction and transmission electron microscopy. The mechanism of this new method was studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2583–2585, 2003