Effect of reaction media on clay dispersion and mechanical properties in poly(butylene succinate)/organoclay nanocomposites

The effect of the reaction media on clay dispersion and mechanical properties in poly(butylene succinate) (PBS, a biodegradable aliphatic thermoplastic polyester)/organoclay nanocomposites was investigated in this article. The results suggested that the most dispersed structures can be observed for organoclay modified in supercritical carbon dioxide (scCO₂), which was used as solvent in the modification of montmorillonite in this study known for its environmentally benign, inexpensive, and nonflammable solvent, high diffusivity like a gas, near‐zero surface tension, low viscosity and density like a liquid, and high‐solvency power tunable by adjusting pressure and then organoclay modified in ethanol, while the least for organoclay was modified in distilled water. The results also confirmed intercalation‐predominate structures were obtained for nanocomposites of PBS with organoclay modified in ethanol, the mixture of intercalated and exfoliated structures for nanocomposites of PBS with organoclay modified in distilled water, but when clay was modified in scCO₂, exfoliation‐predominate structures were observed for the nanocomposites. The storage modulus was significantly enhanced below the glass transition temperature, and the glass transition temperature shifted to a higher temperature compared with pure PBS and the maximum for PBS‐based nanocomposite of pretreated grafted montmorillonite via modification with trihexyltetradecylphosphonium chloride in scCO₂ (OGMMTc). The mechanical properties including tensile strength and notched impact strength first decreased and then increased, whereas flexural strength and flexural modulus steadily and nearly linearly increased, maximum for PBS/OGMMTc nanocomposite, owing to the strong interaction between matrix and clay, which ultimately led to better overall dispersion. J. VINYL ADDIT. TECHNOL., 22:423–432, 2016. © 2015 Society of Plastics Engineers     

Fracture behavior of thermoplastic polyolefin/clay nanocomposites

A thermoplastic polyolefin (TPO) containing 70 wt % styrene–ethylene–butadiene‐styrene‐g‐maleic anhydride and 30 wt % polypropylene and its nanocomposites reinforced with 0.3–1.5 wt % organoclay were prepared by melt mixing followed by injection molding. The mechanical and fracture behaviors of the TPO/clay nanocomposites were investigated. The essential work of fracture (EWF) approach was used to evaluate the tensile fracture behavior of the nanocomposites toughened with elastomer. Tensile tests showed that the stiffness and tensile strength of TPO was enhanced by the addition of low loading levels of organically modified montmorillonite. EWF measurements revealed that the fracture toughness of the TPO/clay nanocomposites increased with increasing clay content. The organoclay toughened the TPO matrix of the nanocomposites effectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Influence of supercritical CO2 on the interactions between maleated polypropylene and alkyl‐ammonium organoclay

Supercritical carbon dioxide (scCO₂) has been proposed as an effective exfoliating agent for the preparation of polymer‐layered silicate nanocomposites, though there is limited fundamental understanding of this mechanism. This study looks at the interactions of this unique green solvent with three maleated polypropylenes of varying anhydride content and molecular size with an alkyl‐ammonium organoclay. Mixtures of compatibilizers and organoclay were melt‐annealed in a high pressure batch vessel at 200°C and subjected to either a blanket of nitrogen or scCO₂ at a pressure of 9.7 MPa. The structures and properties of these melt‐annealed mixtures were characterized by X‐ray diffraction, transmission electron microscopy, Fourier Transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and contact angle measurement. The results indicate that the plasticizing influence of scCO₂ aided intercalation and exfoliation for intercalants of moderate molecular size and anhydride content which would otherwise have limited diffusion into the clay galleries. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Enhanced electrical properties of polycarbonate/carbon nanotube nanocomposites prepared by a supercritical carbon dioxide aided melt blending method

Polycarbonate/carbon nanotube (CNT) nanocomposites were generated using a supercritical carbon dioxide (scCO₂) aided melt blending method, yielding nanocomposites with enhanced electrical properties and improved dispersion while maintaining the aspect ratio of the as-received CNTs. Baytubes^® C 150 P CNTs were benignly deagglomerated with scCO₂ resulting in 5 fold (5X), 10X and 15X decreases in bulk density from the as-received CNTs. This was followed by melt compounding with polycarbonate to generate the CNT nanocomposites. Electrical percolation thresholds were realized at CNT loading levels as low as 0.83 wt% for composites prepared with 15X CNT using the scCO₂ aided melt blending method. By comparison, a concentration of 1.5 wt% was required without scCO₂ processing. Optical microscopy, transmission electron microscopy, and rheology were used to investigate the dispersion and mechanical network of CNTs in the nanocomposites. The dispersion of CNTs generally improved with scCO₂ processing compared to direct melt blending, but was significantly worse than that of twin screw melt compounded nanocomposites reported in the literature. A rheologically percolated network was observed near the electrical percolation of the nanocomposites. The importance of maintaining longer carbon nanotubes during nanocomposite processing rather than focusing on dispersion alone is highlighted in the current efforts.     

Polyaniline–organoclay nanocomposites as curing agent for epoxy: Preparation and characterization

Polyaniline (PANI)–organoclay/Epoxy (EP) nanocomposites were prepared. PANI–organoclay nanocomposites were used as curing agent for EP. Organoclay was prepared by an ion exchange process between sodium cations in MMT and NH₃⁺ groups in polyoxypropylene (D₂₃₀). PANI–organoclay nanocomposite was synthesized by in situ polymerization of aniline in (14 wt%) organoclay. Infrared spectra and differential scanning calorimetry confirm the curing of EP. The absence of d₀₀₁ diffraction band of organoclay in the nanocomposites was observed by X‐ray diffraction. The structure argument was further supported by scanning electron microscopy and transmission electron microscopy. Electrical conductivity of the nanocomposites within the range 2.1 × 10⁻⁷–3.2 × 10⁻⁷ S/cm depending on the concentration of the PANI/D₂₃₀‐MMT. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Supercritical carbon dioxide (scCO2) dispersion of poly(ethylene terephthalate)/clay nanocomposites: Structural,mechanical, thermal,and barrier properties

Dispersed poly(ethylene terephthalate) (PET)/clay nanocomposites can lead to materials with superior barrier and mechanical properties. PET/clay nanocomposites were prepared by melting extrusion of PET with as‐received or supercritical carbon dioxide (scCO₂) predispersed Cloisite^® 30B (30B). The predispersion of 30B was assessed by WAXD, SEM, and TGA, and results indicated that scCO₂ processing could predisperse 30B and the surface modification of the clay was preserved after processing. The structure of PET/30B nanocomposites was investigated by WAXD and TEM confirming that PET has penetrated into the clays inter‐galleries and the predispersed clays lead to improved interfacial interaction and homogenous clay dispersion. Both tensile strength and Young's modulus were improved by 12.1% and 24.9% respectively, as incorporating of 3 wt % of scCO₂ processed clay. Differential scanning calorimetry (DSC) results indicated that clay particles served as nucleation agent could increase the crystallinity whereas had no impact on melting process. In addition, with the addition of 1 wt % of predispersed clay, a significant reduction of oxygen permeation (～33%) was achieved at 23 °C and the maximum reduction (44%) was achieved by adding 3 wt % processed clay. Moreover, we confirmed the effect of temperature on the permeation of PET/30B nanocomposites depended both on the Arrhenius behavior of the organic phases and tortuous path effects, where improved clay dispersion resulted in a higher effective activation energy. Moreover, the transparency of PET matrix was preserved for all nanocomposites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44779.     

Evaluating different alkyl ammonium modified organoclays in preparation of TPO nanocomposites with supercritical CO2

This article examines the chemical structures of the surfactants associated with organically modified montmorillonites in order to understand how differences in the structure may influence the final properties of the nanocomposite materials. Five organically modified montmorillonites with different surfactants were examined in materials prepared using a novel technique for thermoplastic polyolefin nanocomposites, using supercritical CO₂ as a processing aid. The chain length and the number of alkyl chains attached to the quaternary ammonium surfactant were the main variables of study aimed at changing the interactions of an organoclay with compatibilizer and/or polymer matrix due to the CO₂ treatment. The goal of this work was to improve the exfoliation of the dispersed organoclay. The intermediate masterbatch containing organoclay and compatibilizer as well as the final TPO nanocomposites were characterized using X‐ray diffraction (XRD), transmission electron microscopy (TEM), and rheological analysis. The results showed that of the systems tested, significant changes in the state of exfoliation after processing with the supercritical fluid occurred only for surfactants possessing dialkyl tails and exhibiting a paraffin type arrangement within the montmorillonite. POLYM. COMPOS., 35:1592–1602, 2014. © 2013 Society of Plastics Engineers     

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     

Processing and properties of modified polyamide 66-organoclay nanocomposites

Binary polyamide 66 nanocomposites containing 2 wt % organoclay, polyamide 66 blend containing 5 wt % impact modifier, and ternary polyamide 66 nanocomposites containing 2 wt % organoclay and 5 wt % impact modifier were prepared by melt compounding method. The effects of E-GMA and the types of the organoclays on the interaction between the organoclay and the polymer, dispersion of the organoclay, morphology, mechanical, flow, and thermal properties of the nanocomposites were investigated. Partial exfoliation and improved mechanical properties are observed for Cloisite® 15A and Cloisite® 25A nanocomposites. On the other hand, the organoclay was intercalated or in the form of tactoids in Cloisite® 30B nanocomposites. Components of the nanocomposites containing Cloisite® 15A and Cloisite® 25A were compounded in different addition orders. Mixing sequence of the components affected both the dispersion of the organoclay and the mechanical properties drastically. SEM analyses revealed that homogeneous dispersion of the organoclay results in a decrease in the domain sizes and promotes the improvements in the toughness of the materials. Melt viscosity was also found to have a profound effect on the dispersion of the organoclay according to MFI and XRD results. Crystallinity of the nanocomposites did not change significantly. It is only the type of the constituents and their addition order what dramatically influence the nanocomposite properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Preparation and characterization of low density polyethylene/ethylene methyl acrylate glycidyl methacrylate/organoclay nanocomposites

The effects of organoclay type, compatibilizer, and the addition order of components during melt‐blending process on the morphology and thermal, mechanical, and flow properties of ternary nanocomposites based on low‐density polyethylene (LDPE) were investigated. As a compatibilizer, ethylene/methyl acrylate/glycidyl methacrylate (E‐MA‐GMA), as organoclays Cloisites® 15A, 25A, and 30B were used. All samples were prepared by a corotating twin screw extruder, followed by injection molding. The highest increase of the basal spacing for ternary nanocomposites was obtained in LDPE/E‐MA‐GMA/Cloisite® 30B nanocomposites with interlayer spacing of 59.2 Å. Organoclay and compatibilizer addition did not influence the melting/crystallization behavior of the compositions, and both compatibilizer and organoclays had no significant nucleation activity in LDPE. Among the ternary nanocomposites, the maximum increase in tensile strength and tensile modulus values was observed for nanocomposites containing organoclay Cloisite® 15A. The improvement with respect to neat LDPE was 43% for tensile strength and 44% for tensile modulus. According to the mechanical analysis, the best sequence of component addition was the one in which LDPE, organoclay, and compatibilizer were simultaneously fed to the extruder in the first run, and the product of the first run was extruded once more. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Improved mechanical properties of organoclay/nylon 6 nanocomposites prepared via a supercritical carbon dioxide‐aided,melt blending method

The use of supercritical carbon dioxide (scCO₂) as a processing aid to help exfoliate nanoclays and improve their dispersion after melt blending in polymer matrices has been reported in the literature by our laboratory and others. Previous work has focused on nonpolar polymers such as polypropylene. In this work, the supercritical carbon dioxide‐aided, melt blending method with single‐screw compounding was applied to an organoclay/nylon 6 composite system with favorable interactions. Wide‐angle X‐ray diffraction, transmission electron microscopy, dynamic mechanical testing, and tensile tests are provided to investigate the effect of processing with scCO₂ on the final composite morphology and properties. It was found that properties of composites prepared with the scCO₂‐aided method were similar to or higher than those reported in the literature for samples prepared with twin‐screw compounding. At 7.6 wt% the modulus value reached 4.75 GPa which is one of the highest increases (1.7 GPa) reported for these materials processed at intermediate concentrations. Beyond 7.6 wt% the improvement due to scCO₂ processing matches that of direct blending. It is possible that with the use of a twin‐screw extruder, the modulus would continue to increase. The use of nylon illustrates the importance of having functionalities that can interact with the clay during scCO₂‐aided melt compounding. POLYM. COMPOS. 36:527–537, 2015. © 2014 Society of Plastics Engineers     

Polybutadiene rubber/organoclay nanocomposites: Effect of organoclay with various modifier concentrations on the vulcanization behavior and mechanical properties

It has been reported that the cure time t₉₀, scorch time t₂, and their difference (t₉₀?t₂) of Polybutadiene rubber (BR)/organoclay nanocomposites were much reduced over those of BR. This effect can be attributed to the ammonium groups in the organoclay. The possible formation of a Zn complex in which sulfur and ammonium modifier participate may facilitate the formation of crosslinks. If this assumption is true, it is expected that the organoclay with higher ammonium modifier concentration will give larger torque difference and faster vulcanization rate to the BR/organoclay nanocomposites. The effect of organoclay with different modifier concentration on the vulcanization behavior and mechanical properties of BR/organoclay hybrid was investigated in this study. As expected, the order of the torque difference was BR/Cloisite 15A > BR/Cloisite 10A > BR/Cloisite 20A > BR/Cloisite 25A > BR/Cloisite 30B > BR/Cloisite Na⁺, and the order of vulcanization rate also showed similar trends. The organoclay with higher modifier concentration gave larger torque difference and faster vulcanization rate to the BR/organoclay nanocomposites. POLYM. ENG. SCI., 47:308–313, 2007. © 2007 Society of Plastics Engineers.     

Supercritical CO2 dispersion of nano-clays and clay/polymer nanocomposites

Dispersed polymer/clay nanocomposites are of great interest because they can significantly improve the properties of existing polymeric materials. However, achieving a high level of clay dispersion has been a key challenge in the production of polymer/clay nanocomposites. In this paper, we explore a novel supercritical carbon dioxide (scCO₂) processing method that utilizes scCO₂ to disperse nano-clays. The structure and properties of the clays and the resultant nanocomposites are characterized using a combination of wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and rheology. Significant dispersion was achieved with dry Cloisite 93A clay, whereas relatively poor dispersion was achieved with dry Cloisite Na⁺ (natural clay). The extent of clay dispersion appears to be dependent on the ‘CO₂-philicity’, which in turn appears to depend on the surface modifications and inter-gallery spacing. The presence of an acidic hydrogen on the surfactant in Cloisite 93A appears to play a strong role in its ‘CO₂-philicity’. The ability to delaminate dry clays is significant because it will likely increase the ability to produce dispersed clay/polymer nanocomposites via melt processing. In addition to delaminating dry clays, we demonstrate that CO₂-phobic Cloisite Na⁺ (natural clay) can be partially dispersed with scCO₂, using a CO₂-philic polymer, polydimethylsiloxane (PDMS). The dispersed clay/PDMS nanocomposite shows an order of magnitude increase in the dynamic storage modulus at low frequencies, accompanied by the emergence of a ‘solid-like’ plateau, characteristic of dispersed nanocomposites with enhanced clay/polymer interactions.     

The effect of polyoxypropylene‐montmorillonite intercalates on polymethylmethacrylate

Polymethylmethacrylate (PMMA)‐layered silicate nanocomposites have been prepared by in situ polymerization of commercial type of methylmethacrylate monomer (MMA), for denture base material, into organoclay. Organoclay was prepared through an ion exchange process between sodium cations in montmorillonite and NH₃⁺ groups in polyethertriamine hydrochloride and polyoxypropylene triamine hydrochloride with different molecular weight (5000, 440). X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been used to investigate the structure of the resulting composites. Both intercalated and exfoliated nanocomposites were obtained depending on the type and amount of organoclay. The thermal decomposition temperatures of the nanocomposites were found to be higher than that of pristine polymer. PMMA was strongly fixed to inorganic surfaces, due to cooperative formation of electrostatic bonding between NH₃⁺ group and negatively charged surface of layered silicate and amide linkage between PMMA and polyethertriamine or polyoxypropylene triamine. The effect of the organoclay on the hardness, toughness, tensile stress, and elongation at break of the polymer was studied and was compared with pristine polymer. The hardness and Izod impact strength of PMMA‐organoclay nanocomposites were enhanced with the inclusion of clay. Tensile properties appear to be enhanced at certain organoclay content. However, the water absorption is slightly higher than the pristine PMMA. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Rheological behavior of polypropylene/layered silicate nanocomposites prepared by melt compounding in shear and elongational flows

Melt rheology and processability of exfoliated polypropylene (PP)/layered silicate nanocomposites were investigated. The nanocomposites were prepared by melt compounding process in the presence or absence of a PP‐based maleic anhydride compatibilizer. PP/layered silicate nanocomposites showed typical rheological properties of exfoliated nanocomposites such as nonterminal solid‐like plateau behavior at low frequency region in oscillatory shear flow, higher steady shear viscosity at low shear rate region, and outstanding strain hardening behavior in uniaxial elongational flow. The melt processability of exfoliated PP/layered silicate nanocomposites was significantly improved due to good dispersion of layered silicates and increased molecular interaction between the PP matrix and the layered silicate organoclay. Small‐angle X‐ray scattering and transmission electron microscopy results revealed that the layered silicate organoclay was exfoliated and good interaction between PP matrix and organoclay was achieved by using the PP‐g‐MAH compatibilizer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3506–3515, 2007     

Synthesis of hybrid nanocomposites based on new triazeno copolymers and montmorillonite used for detecting metal ions

The modern synthesis of novel functional materials with improved properties includes that of hybrid nanocomposites composed of inorganic nanoparticles and organic derivatives, where controlling the molecular structure at atomic and macroscopic dimensions is a key factor, with a major effect on performance. An extension of this approach to the field of nanocomposites containing photopolymers with triazene groups attached on a methacrylic backbone could be of great interest in the future development of chemosensors and photoresists, among others. Photopolymer/clay nanocomposites were prepared by in situ free radical copolymerization of 1‐(phenyl)‐3‐(2‐methacryloyloxyethylcarbamoyloxyethyl)‐3‐methyltriazene‐1 or 1‐(p‐methoxyphenyl)‐3‐(2‐methacryloyloxyethylcarbamoyloxyethyl)‐3‐methyltriazene‐1 and vinyl acetate or styrene in solution and in the presence of 3 and 5 wt% of organically modified montmorillonite. The characterization of the nanocomposites and pure copolymers was achieved through ¹H NMR and Fourier transform infrared spectroscopy, gel permeation chromatography, thermogravimetric analysis, X‐ray diffraction, atomic force microscopy and fluorescence analysis. The morphologies and properties of the nanocomposites are dependent on the nature of the triazene, on the co‐monomer structure and on the organoclay content. Also, the fluorescence response of these nanocomposites towards certain metal ions (Fe³⁺, Cu²⁺, Hg²⁺, Ni²⁺) in dimethylformamide solution was investigated. The effect of uranyl ions on the fluorescence intensity of the nanocomposites in solution or as films could be exploited in the development of ‘turn‐off’ or ‘turn‐on’ chemosensors for this type of analyte. Triazeno copolymer/organophilic montmorillonite nanocomposites with exfoliated (not completely exfoliated) or exfoliated and intercalated structures exhibit distinct characteristics concerning their fluorescence behaviour, a higher sensing ability towards certain target compounds (Fe³⁺, UO₂²⁺) being evidenced for those incorporating 3 wt% organoclay in solution and as films. Copyright © 2010 Society of Chemical Industry     

Biopolymer nanocomposites based on poly(hydroxybutyrate‐co‐hydroxyvalerate) reinforced by a non‐ionic organoclay

In this study, a nanocomposite based on a biodegradable polymer poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV) reinforced by triethylene glycol mono‐n‐decyl ether (C₁₀E₃) non‐ionic organoclay (C₁₀E₃‐Mt) was prepared. The morphology and the thermal and mechanical properties of PHBV/C₁₀E₃‐Mt were compared with those of PHBV nanocomposites prepared using commercial organically modified montmorillonite Cloisite^® 30B (OMt) and raw montmorillonite (Mt). Nanocomposites with 3 wt% nanoparticles were obtained by melt processing. The high level of dispersion with improved interfacial interactions between OMt and polymer led to an increase in the thermal stability and modulus of PHBV. However, this nanocomposite presented a lower strain before fracture, typical of brittle behavior. The transmission electron microscopy and wide angle X‐ray diffraction results revealed a significant increase in the interlayer spacing of clay for the PHBV/C₁₀E₃‐Mt nanocomposite, which was favored by the wide expansion of the platelets of the starting non‐ionic organoclay. This characteristic of C₁₀E₃‐Mt, together with its hydrophobic behavior, allowed its easy incorporation in the PHBV matrix, thus improving the processing and maintaining a high modulus with increased material toughness. © 2014 Society of Chemical Industry     

Preparation of poly(lactic acid)/poly(ethylene glycol)/organoclay nanocomposites by melt compounding

Poly(lactic acid) (PLA)/organoclay nanocomposites were prepared by melt compounding in a co‐rotating twin screw extruder. Two types of commercialized organoclay (dimethyl benzyl stearyl ammonium ion and dimethyl distearyl ammonium ion intercalated between clay platelets named as Clay A and Clay B, respectively) and two grades of poly(ethylene glycol) (PEG) with different molecular weight (M_w = 2,000 and 300,000–500,000 named as PEG2k and PEG500k, respectively) were used in this study. The Young's modulus improved by the addition of organoclay to PLA matrix. The Young's modulus decreased with the addition of PEG to PLA/organoclay nanocomposites. The tensile strength and elongation of PLA/Clay B nanocomposites increased with the addition of PEG2k. The effect of the addition of PEG on d‐spacing of PLA/organoclay nanocomposites is dependent upon the kind of organoclay. The sizes of clay agglomerations in PLA/PEG/organoclay nanocomposites are larger than those of PLA/organoclay ones in the same organoclay. Addition of PEG to PLA/organoclay nanocomposites during melt compounding will not be useful for the preparation of PLA/organoclay having fully exfoliated clay platelets. The shear thinning properties of the nanocomposites are independent of the addition of PEG. On the whole, PEG2k is good plasticizer for PLA/organoclay nanocomposites. POLYM. COMPOS. 27:256–263, 2006. © 2006 Society of Plastics Engineers     

Effect of water‐assisted extrusion and solid‐state polymerization on the microstructure of PET/Clay nanocomposites

An melt‐mixing process has been used to prepare Poly(ethylene terephthalate) (PET)/clay nanocomposites with high degree of clay delamination. In this method, steam was fed into a twin‐screw extruder (TSE) to reduce the PET molecular weight and to facilitate their diffusion into the gallery spacing of organoclays. Subsequently, the molecular weight (M_W) reduction of the PET matrix due to hydrolysis by water was compensated by solid‐state polymerization (SSP). The effect of the thermodynamic compatibility of PET and organoclays on the exfoliated microstructure of the nanocomposites was also examined by using three different nanoclays. The dispersion of Cloisite 30B (C30B) in PET was found to be better than that of Nanomer I.28E (I28E) and Cloisite Na⁺. The effect of feeding rate and consequently residence time on the properties of PET nanocomposites was also investigated. The results reveal more delamination of organoclay platelets in PET‐C30B nanocomposites processed at low feeding rate compared to those processed at high feeding rate. Enhanced mechanical and barrier properties were observed in PET nanocomposites after SSP compared to the nanocomposites prepared by conventional melt‐mixing. POLYM. ENG. SCI., 54:1723–1736, 2014. © 2013 Society of Plastics Engineers     

Mechanical,thermal, barrier,and rheological properties of poly(ether‐block‐amide) elastomer/organoclay nanocomposite prepared by melt blending

Polyether block amide (PEBA) elastomer‐organoclay nanocomposites were prepared by a melt mixing technique. The X‐ray diffraction and transmission electron microscope analysis indicated that the nanocomposite formed a partially exfoliated nanostructure in which the organoclay was dispersed uniformly throughout the matrix at the nanometer scale. The effect of organoclay on the melting temperature (T_m), glass transition temperature (T_g), crystallization temperature (T_c), and heat of fusion (ΔH_m) of the PEBA was determined by differential scanning calorimetry. Enhanced mechanical properties of the nanocomposites were observed from tensile and dynamic mechanical analysis. Thermal gravimetric analysis showed that the clay nanoparticles caused an increase in the thermal stability of the PEBA. Measurement of oxygen permeability and the degree of swelling in ASTM #3 oil indicated that the gas barrier properties and solvent resistance were greatly improved by the clay nanoparticles. Melt rheological studies revealed that the nanocomposites exhibited strong shear thinning behavior and a percolated network of the clay particles was formed. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers