Novel in situ carbon nanofiber/polydimethylsiloxane nanocomposites: Synthesis,morphology, and physico‐mechanical properties

A series of carbon nanofiber (CNF)/polydimethylsiloxane (PDMS)‐based nanocomposites was prepared by anionic ring opening polymerization of octamethylcyclotetrasiloxane (D₄) in presence of pristine CNF and amine‐modified CNF. A detailed study of morphology–property relationship of the nanocomposites was carried out in order to understand the effect of chemical modification and loading of filler on property enhancement of the nanocomposites. An elaborate comparison of structure and properties was carried out for the nanocomposites prepared by in situ and conventional ex situ methods. Pronounced improvement in degree of dispersion of the fillers in the matrix on amine modification of CNFs was reflected in mechanical properties of the modified nanocomposites. Maximum upliftment in mechanical properties was observed for in situ prepared amine modified CNF/hydroxyl PDMS nanocomposites. For 8 phr filler loading, tensile strength increased by 370%, while tensile modulus showed an increase of 515% compared with the virgin elastomer. Furthermore, in situ prepared unmodified CNF/hydroxyl PDMS nanocomposites showed an increase of 141°C in temperature of maximum degradation (T_max) for 8 phr CNF loading. These results were correlated with the morphological analysis through transmission electron microscopic studies. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characterization of sepiolite‐poly(ethyl methacrylate) and poly(2‐hydroxyethyl methacrylate) nanocomposites

Poly(ethyl methacrylate) (PEMA) and poly(2‐hydroxyethyl methacrylate) (PHEMA) nanocomposites with sepiolite in pristine and silylated form were prepared using the solution intercalation method and characterized by the measurements of XRD, TEM, FTIR‐ATR, TG/DTG, and DSC. The TEM analysis indicated that the volume fraction of fibers in sepiolite decreased and the fiber bundles dispersed in PEMA and PHEMA at a nanometer scale. These results regarding TEM micrographs were in agreement with the data obtained by XRD. The increase in thermal stability of nanocomposites of PEMA is higher than that of PHEMA according to the data obtained from TG curves. The DTG analysis revealed that sepiolite/modified sepiolite caused some changes, as confirmed by FTIR in the thermal degradation mechanism of the polymers. T_g temperatures of PEMA and PHEMA usually increased upon the addition of sepiolite/modified sepiolite. In addition, modification of sepiolite with 3‐APTS had a slight influence on thermal properties of the nanocomposites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Effect of clay platelet dispersion as affected by the manufacturing techniques on thermal and mechanical properties of PMMA‐clay nanocomposites

In this work, the properties of Poly(methyl methacrylate) (PMMA)‐clay nanocomposites prepared by three different manufacturing techniques viz., solution mixing, melt mixing, and in‐situ bulk polymerization in presence of clay were studied. Morphological analysis revealed that the extent of intercalation and dispersion of the nanoclay were relatively higher in the in‐situ polymerized nanocomposites than those of solution and melt blended nanocomposites. Differential Scanning Calorimetric study indicated maximum increment in T_g of the PMMA in the in‐situ polymerized PMMA‐clay nanocomposites. Thermo gravimetric analysis showed improved thermal stability of PMMA in all the nanocomposites and the maximum improvement was for in‐situ polymerized nanocomposites. The storage moduli of all the nanocomposites were higher than the pure PMMA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Thermal stability and dynamic mechanical behavior of exfoliated graphite nanoplatelets‐LLDPE nanocomposites

The objective of this research was to investigate thermal stability and dynamic mechanical behavior of Exfoliated graphite nanoplatelets (xGnP™)‐Linear Low‐Density Poly Ethylene (LLDPE) nanocomposites with different xGnP loading content. The xGnP‐LLDPE nanocomposites were fabricated by solution and melt mixing in various screw rotating systems such as co‐, counter‐, and modified‐corotating. The storage modulus (E′) of the composites at the starting point of −50°C increased as xGnP contents increased. E′ of the nanocomposite with only 7 wt% of xGnP was 2.5 times higher than that of the control LLDPE. Thermal expansion and the coefficient of thermal expansion of xGnP‐loaded composites were much lower than those of the control LLDPE in the range of 45–80°C (299.8 × 10⁻⁶/°C) and 85–100°C (365.3 × 10⁻⁶/°C). Thermal stability of the composites was also affected by xGnP dispersion in LLDPE matrix. The xGnP‐LLDPE nanocomposites by counter‐rotating screw system showed higher thermal stability than ones by co‐rotating and modified‐co‐rotating system at 5 wt% and 12 wt% of xGnP. xGnP had a great effect on high thermal stability of xGnP‐LLDPE composites to be applied as tube and film for electrical materials. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

In situ dynamic vulcanization process in preparation of electrically conductive PP/EPDM thermoplastic vulcanizate/expanded graphite nanocomposites: Effects of state of cure

In situ melt dynamic vulcanization process has been employed to prepare electrically conductive polypropylene (PP)/ethylene–propylene–diene rubber (EPDM) (40/60 wt %) thermoplastic vulcanizates (TPVs) incorporated by expanded graphite (EG) as a conductive filler. Maleic anhydride grafted PP (PP‐g‐MAH) was used as compatibilizer and a sulfur curing system was designed and incorporated to vulcanize the EPDM phase during mixing process. Developed microstructures were characterized using scanning electron microscopy (SEM), melt rheomechanical spectroscopy (RMS), X‐ray diffraction (XRD), and transmission electron microscopy (TEM) and were correlated with electrical conductivity behavior. For comparison, another class of TPV/EG nanocomposites was fabricated using a commercially available PP/EPDM‐based TPV via both direct and masterbatch melt mixing process. Conductivity of the nanocomposites prepared by in situ showed no significant change during dynamic vulcanization till the mixing torque reached to the stationary level where micro‐morphology of the cured rubber droplets was fully developed, and conductivity abrupt was observed. In situ cured nanocomposites showed higher insulator to conductor transition threshold (3.15 vol % EG) than those based on commercially available TPV. All electrically conductive in situ prepared TPV nanocomposites exhibited reinforced melt elasticity with pseudosolid‐like behavior within low frequency region in dynamic melt rheometry indicating formation of physical networks by both EG nanolayers and crosslinked EPDM droplets. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Studies on the thermal stability and degradation kinetics of Pd/PC nanocomposites

Effect of heating rate, Pd content, and synthesis method on the thermal stability of the ex situ and in situ Palladium/polycarbonate (Pd/PC) nanocomposites was investigated. TEM images revealed discrete Pd nanoclusters of about 5 and 15 nm sizes for 1 and 2 vol % ex situ nanocomposites, respectively. However, agglomerated Pd nanoclusters were noticed in the in situ samples, irrespective of the Pd content. The ex situ Pd/PC nanocomposites showed high onset temperature (Ti) for thermal degradation of PC than the in situ and pure PC samples. Pd content and heating rates were found to have a positive influence on the Ti and Tm (temperature at the maximum degradation rate occurs) of the Pd/PC nanocomposites. Thermal degradation of the PC was found to follow the first‐order kinetics in the Pd/PC nanocomposites. The activation energies associated with the degradation were determined by using the Kissinger method. These activation energies are used to construct the Master decomposition curve (MDC) and weight–time–temperature (α–t–T) plots that describe the time‐temperature dependence of the PC pyrolysis in the Pd/PC nanocomposites. These constructed α–t–T plots were validated with the data from isothermal measurements. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Influence of sepiolite and electron beam irradiation on the structural and physicochemical properties of polyethylene/starch nanocomposites

This study presents the influence of functionalized sepiolite and electron beam irradiation on the structural and physicochemical properties of high density polyethylene (HDPE)/starch blends. HDPE/Starch blends containing varying amounts of sepiolite [from 2 to 6 parts per hundred (phr) resins] were prepared in an internal mixer and subjected to electron beam irradiation. The structural analysis of nanocomposites revealed an interaction among the incorporated components. The morphological analysis depicted the void‐free dispersion of additives in the nanocomposites as well as an improvement in the compatibility between the matrix and additives. The sepiolite served as a heat barrier and improved the thermal stability of blend upto a maximum of 45°C. The ultimate tensile strength and Young's modulus (E) of blend was slightly improved with the incorporation of sepiolite and radiation. On the contrary, the E of nanocomposites was significantly improved with radiation dose. The sample containing 6 phr sepiolite and irradiated at 100 kGy showed 61% increase in E when compared with its unirradiated counterpart. Likewise, the thermal distortion temperature and Vicat softening temperature of the blend was slightly changed with the incorporation of sepiolite and radiation dose; however, increased with radiation dose in the nanocomposites. The improvements in the properties of nanocomposites with radiation dose were assigned to the formation of radiation‐induced crosslinked network as revealed by gel content analysis. The results presented here revealed substantial improvements in the properties of nanocomposites with irradiation, which pave way for their potential applications in various sectors including packaging materials for radiation sterilizable products. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Natural Rubber Nanocomposites by In Situ Modification of Clay

The fabrication of nanocomposites by organic modification of clay during mixing into NR is reported. NR/OMMT nanocomposites show more intercalation and exfoliation at higher modifier content, increasing the tensile modulus primarily by improved filler reinforcement. Comparison with nominally identical pre‐modified OMMT shows similar microstructures and physical properties. No effect of mixing duration is observed, indicating that modification is rapid. Unlike montmorillonite, unmodified sepiolite disperses well in NR, so organo‐modification improves compatibility but does not affect the nanocomposite microstructure. This means that organo‐sepiolite offers relatively small improvements over sepiolite as a filler for NR.

     

Preparation and properties of unsaturated polyester nanocomposites based on silylated sepiolite nanofibers

The novel surface‐modified sepiolite/unsaturated polyester (sepiolite/UP) nanocomposites were prepared by in situ polymerization. Sepiolite fibers were first organo‐modified by grafting of vinyltriethoxysilane (VTS) containing a double bond onto the surfaces and used as nanofillers. The morphology of sepiolites and nanocomposites were characterized by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and transmission electron microscope (TEM). Moreover, the thermal properties were determined by thermogravimetric analysis (TGA) and the thermal degradation mechanism was discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Kinetics of thermal degradation of nanometer calcium carbonate/linear low‐density polyethylene nanocomposites

To improve the thermal properties of linear low‐density polyethylene (LLDPE), the CaCO₃/LLDPE nanocomposites were prepared from nanometer calcium carbonate (nano‐CaCO₃) and LLDPE by melt‐blending method. A series of testing methods such as thermogravimetry analysis (TGA), differential thermogravimetry analysis, Kim‐Park method, and Flynn‐Wall‐Ozawa method were used to characterize the thermal property of CaCO₃/LLDPE nanocomposites. The results showed that the CaCO₃/LLDPE nanocomposites have only one‐stage thermal degradation process. The initial thermal degradation temperature T₀ increasing with nano‐CaDO₃ content, and stability of LLDPE change better. The thermal degradation activation energy (E_a) is different for different nano‐CaCO₃ content. When the mass fraction of nano‐CaCO₃ in nanocomposites is up to 10 wt %, the nanocomposite has the highest thermal degradation E_a, which is higher (28 kJ/mol) than pure LLDPE. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

The influence of in situ modification of silica on filler network and dynamic mechanical properties of silica‐filled solution styrene–butadiene rubber

The influence of in situ modification of silica with bis‐(3‐(triethoxysilyl)‐propyl)‐tetrasulfide (TESPT) on filler network in silica filled solution SBR compound was investigated. In situ modification greatly increased the bound rubber content. TEM observation of silica gel showed that bridging and interlocking of absorbed chains on the surface of silica particles formed the filler network. Rubber processing analyzer (RPA) was used to characterize the filler network and interaction between silica and rubber by strain and temperature sweeps. In situ modification improved the dispersion of silica, and in the meantime, the chemical bonds were formed between silica and rubber, which conferred the stability of silica dispersion during the processing. Compared to the compound without in situ modification, the compound with in situ modification of silica exhibited higher tan δ at low strains and lower tan δ at high strains, which can be explained in terms of filler network in the compounds. After in situ modification, DMTA results showed silica‐filled SSBR vulcanizate exhibited higher tan δ in the temperature range of ?30 to 10°C, and RPA results showed that it had lower tan δ at 60°C when the strain was more than 3%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Mesua ferrea L. seed oil based acrylate-modified thermostable and biodegradable highly branched polyester resin/clay nanocomposites

Mesua ferrea L. seed oil based highly branched polyester resin was modified by methyl methacrylate through grafting polymerization technique. The nanocomposites of this acrylate-modified polyester and 1–5 wt% loadings of organically modified montmorrilonite (OMMT) nanoclay were prepared by an ex situ technique using strong mechanical mixing and ultrasonication. Formation of nanocomposites was confirmed by X-ray diffractometeric (XRD), scanning electron microscopic (SEM) and transmission electron microscopic (TEM) analyses. The absence of d_{0 0 1} reflections of OMMT in XRD and TEM study revealed the partial exfoliation of OMMT by the polymer chain. The homogeneous surface morphology was also ascertained from SEM. Mechanical and thermal studies of the nanocomposites showed an appreciable improvement in tensile strength and thermal stability by OMMT loading. The enhancement of tensile strength by 2.5 times and thermal stability by 32 °C for 5 wt% OMMT filled nanocomposite was observed compared to that of pristine system. The rheological behavior of the nanocomposites was also investigated and shear thinning was observed. Biodegradation of the nanocomposite films was assayed using two strains of Pseudomonas aeruginosa, SD2 and SD3 and one strain of Bacillus subtilis, MTCC736. The nanocomposites exhibited enhanced biodegradability as compared to pristine acrylate modified polyester. All the results showed the potentiality of the nanocomposites as advanced thin film materials for suitable applications.     

Characterization of nanocomposite resol resins: Individual/synergist effects of alendronic acid and sepiolite

Alendronic acid modified resol nanocomposite resins (AA‐PFNCRs) and sepiolite modified resol nanocomposite resins (SEP‐PFNCRs) have been synthesized by in situ method in the presence of base catalyst. Additionally, the synergistic effects of alendronic acid and sepiolite clay (AA‐SEP‐PFNCR) on the resol resin have been studied. The structure, morphology, and thermal properties of these nanocomposites have been investigated by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and X‐ray Diffraction (XRD). The results demonstrated the interactions between the fillers and resol resin. Thermal properties of nanocomposite resins were improved due to alendronic acid and sepiolite. The obtained samples were also characterized morphologically by Scanning Electron Microscope (SEM). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43807.     

Preparation and properties of polyethylene/montmorillonite nanocomposites formed via ethylene copolymerization

BACKGROUND: In situ formation of polyethylene/clay nanocomposites is one of the prevalent preparation methods that include also solution blending and melt blending with regard to process simplification, economy in cost, environment protection and marked improvement in the mechanical properties of the polymeric matrix. In the work reported here, the preparation of linear low‐density polyethylene (LLDPE) and fabrication of polymer/clay nanocomposites were combined into a facile route by immobilizing pre‐catalysts for ethylene oligomerization on montmorillonite (MMT). RESULTS: [(2‐ArN?C(Me))₂C₅H₃N]FeCl₂ (Ar = 2,4‐Me₂(C₆H₃)) was supported on MMT treated using three different methods. The MMT‐supported iron complex together with metallocene compound rac‐Et(Ind)₂ZrCl₂ catalyzed ethylene to LLDPE/MMT nanocomposites upon activation with methylaluminoxane. The oligomer that was formed between layers of MMT promoted further exfoliation of MMT layers. The LLDPE/MMT nanocomposites were highly stable upon heating. Detailed scanning electron microscopy analysis revealed that the marked improvement in impact strength of the LLDPE/MMT nanocomposites originated from the dispersed MMT layers which underwent cavitation upon impact and caused plastic deformation to absorb most of the impact energy. In general, the mechanical properties of the LLDPE/MMT nanocomposites were improved as a result of the uniform dispersion of MMT layers in the LLDPE matrix. CONCLUSION: The use of the MMT‐supported iron‐based diimine complex together with metallocene led to ethylene copolymerization between layers of MMT to form LLDPE/MMT nanocomposites. The introduction of exfoliated MMT layers greatly improved the thermal stability and mechanical properties of LLDPE. Copyright © 2009 Society of Chemical Industry     

Multifunctional xGnP/LLDPE Nanocomposites Prepared by Solution Compounding Using Various Screw Rotating Systems

xGnP‐Reinforced LLDPE nanocomposites have been prepared using co‐, counter‐ and modified co‐rotating screw systems. The highest tensile strength and modulus were shown in the case of composites made by counter‐rotating screws. The percolation threshold of exfoliated graphite nanoplatelet/LLDPE nanocomposites was between 12 and 15 wt.‐%. The change of crystallinity caused by exfoliated graphite nanoplatelet loading was monitored using DSC and XRD. It was found that solution mixing showed better dispersion of exfoliated graphite nanoplatelets than melt mixing, and counter‐rotating screws produced better dispersion of the exfoliated graphite nanoplatelets than co‐ and modified co‐rotating screws even though bubbling appeared during mixing in the barrel.

     

Use of a new natural clay to produce poly(methyl methacrylate)‐based nanocomposites

Nanocomposites of poly(methyl methacrylate) (PMMA) filled with 3 wt% of modified natural Algerian clay (AC; montmorillonite type) were prepared by either in situ polymerization of methyl methacrylate initiated by 2,2′‐azobisisobutyronitrile or a melt‐mixing process with preformed PMMA via twin‐screw extrusion. The organo‐modification of the AC montmorillonite was achieved by ion exchange of Na⁺ with octadecyldimethylhydroxyethylammonium bromide. Up to now, this AC montmorillonite has found applications only in the petroleum industry as a rheological additive for drilling muds and in water purification processes; its use as reinforcement in polymer matrices has not been reported yet. The modified clay was characterized using X‐ray diffraction (XRD), which showed an important shift of the interlayer spacing after organo‐modification. The degree of dispersion of the clay in the polymer matrix and the resulting morphology of nanocomposites were evaluated using XRD and transmission electron microscopy. The resulting intercalated PMMA nanocomposites were analysed using thermogravimetric analysis and differential scanning calorimetry. The glass transition temperature of the nanocomposites was not significantly influenced by the presence of the modified clay while the thermal stability was considerably improved compared to unfilled PMMA. This Algerian natural montmorillonite can serve as reinforcing nanofiller for polymer matrices and is of real interest for the fabrication of nanocomposite materials with improved properties. Copyright © 2009 Society of Chemical Industry     

Preparation and characterization of poly(styrene‐b‐butadiene‐b‐styrene)/montmorillonite nanocomposites

With some polymerizable small molecules grafting onto the montmorillonite surface, we disposed the clay through in‐situ emulsion polymerization, and the structure of the modified montmorillonites were studied through Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD). The nanocomposites of poly(styrene‐b‐butadiene‐b‐styrene) (SBS)/montmorillonite with excellent mechanical properties were prepared by mixing SBS and the modified montmorillonite on the double rollers at 150°C. The exfoliation of the layered silicates was confirmed by XRD analysis and transmission electron microscopy (TEM) observation. After mechanical kneading of the molten nanocomposites, the exfoliation structure of the silicates is still stable for polystyrene macromolecules grafting onto the silicates. Upon the addition of the modified montmorillonite, the tensile strength, elongation at break and tear strength of the nanocomposites increased from 22.6 MPa to 31.1 MPa, from 608% to 948%, from 45.32 N/mm to 55.27 N/mm, respectively. The low‐temperature point of glass‐transition temperature (T_g) of the products was about −77°C, almost constant, but the high‐temperature point increased from 97°C to 106°C. In addition, the nanocomposites of SBS and modified montmorillonites showed good resistance to thermal oxidation and aging. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Characteristics of polystyrene/polyethylene/clay nanocomposites prepared by ultrasound‐assisted mixing process

In this study, polymer‐clay nanocomposites of various concentrations were prepared by ultrasonically assisted polymerization and melt‐mixing processes. A sonication process using power ultrasonic waves was employed to enhance nano‐scale dispersion during melt‐mixing of polymer blends and organically modified clay. We expected enhanced breakup of layered silicate bundles and further reduction in the size of the dispersed phase, with better homogeneity compared to the different immiscible blend pairs. X‐ray diffraction (XRD) and Transmission Electron Microscopy (TEM) were used to characterize the structures of the nanocomposites. The rheological behaviors of the obtained nanocomposites were measured with parallel plate rheometry. It was found that the ultrasound‐assisted process successfully generated exfoliated nanocomposites and promoted in‐situ compatibilization of the matrix comprising an immiscible pair of polymers in a blend. The resulting nanocomposite exhibited superior thermal stability and elastic modulus compared to the base polymer. Polym. Eng. Sci. 44:1198–1204, 2004. © 2004 Society of Plastics Engineers.     

Phosphonium‐based layered silicate—Poly(ethylene terephthalate) nanocomposites: Stability,thermal and mechanical properties

PET‐clay nanocomposites were prepared using alkyl quaternary ammonium and phosphonium modified clays by melt‐mixing at 280°C using a micro twin screw extruder. The latter clays were prepared by synthesizing phosphonium surfactants using a simple one‐step method followed by a cation exchange reaction. The onset temperature of decomposition (T_onset) for phosphonium clays (>300°C) was found to be significantly higher than that of ammonium clays (around 240°C). The clay modified with a lower concentration (0.8 meq) of phosphonium surfactant showed a higher T_onset as compared to the clay modified with a higher concentration (1.5 meq) of surfactants. Nanocomposites prepared with octadecyltriphenyl phosphonium (C18P) modified clay showed a higher extent of polymer intercalation as compared with benzyltriphenylphosphonium (BTP) and dodecyltriphenylphosphonium (C12P) modified clays. The nanocomposites prepared with ammonium clays showed a significant decrease in the molecular weight of PET during processing due to thermal degradation of ammonium surfactants. This resulted in a substantial decrease in the mechanical properties. The molecular weight of PET was not considerably reduced during processing upon addition of phosphonium clay. The nanocomposites prepared using phosphonium clays showed an improvement in thermal properties as compared with ammonium clay‐based nanocomposites. T_onset increased significantly in the phosphonium clay‐based nanocomposites and was higher for nanocomposites which contained clay modified with lower amount of surfactant. The tensile strength decreased slightly; however, the modulus showed a significant improvement upon addition of phosphonium clays, as compared with PET. Elongation at break decreased sharply with clay. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of Ionomeric Compatibilizer on Clay Dispersion in Polyethylene/Clay Nanocomposites

Summary: Linear low‐density polyethylene (LLDPE)/clay nanocomposites are obtained and studied by using a zinc‐neutralized carboxylate ionomer as a compatibilizer. LLDPE‐g‐MA is used as a reference compatibilizer. Two different clays, natural montmorillonite (Closite Na⁺) and a chemically modified clay Closite 20A have been used. Nanocomposites are prepared by melt blending in a twin‐screw extruder using two mixing methods: two‐step mixing and one‐step mixing. The relative influence of each compatibilizer is determined by wide‐angle X‐ray diffraction structural analysis and mechanical properties. The results are analyzed in terms of the effect of the compatibilizing agent and incorporation method in the clay dispersion, and the mechanical properties of the nanocomposites. Experimental results confirm that the film samples with ionomer show a good mechanical performance only slightly below that of the samples with maleic anhydride (MA). The two‐step mixing conditions result in better dispersion and intercalation for the nanofillers than one‐step mixing. The exfoliation of clay platelets leads to an improved thermal stability of the composite. The oxygen permeability of the clay nanocomposites, using ionomer as a compatibilizer, is decreased by the addition of the clay.

TEM image of a PE/4 wt.‐% Closite 20A nanocomposite formed using ionomer.