Preparation and properties of heterocyclically conjugated poly(3‐hexylthiophene)–clay nanocomposite materials

A series of heterocyclically conjugated polymer–clay nanocomposite (PCN) materials that consisted of organic poly(3‐hexylthiophene) (P3HT) and inorganic montmorillonite (MMT) clay platelets were prepared by in situ oxidative polymerization with FeCl₃ as an oxidant. The as‐synthesized PCN materials were characterized by Fourier transform infrared (FTIR) spectroscopy, wide‐angle powder X‐ray diffraction (WAXRD), and transmission electron microscopy (TEM). The effects of the material composition on the anticorrosion, gas barrier, thermal stability, flammability, mechanical strength, and electrical conductivity properties of the P3HT and PCN materials were studied by electrochemical corrosion measurements, gas‐permeability analysis (GPA), thermogrametric analysis (TGA), limiting oxygen index (LOI) measurements, dynamic mechanical analysis (DMA), and a four‐point probe technique, respectively. The molecular weights of extracted and bulk P3HT were determined by gel permeation chromatography (GPC) with THF as an eluant. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3438–3446, 2004     

Interfacial interaction and mechanical properties of chitin whisker–poly(vinyl alcohol) gel‐spun nanocomposite fibers

Nanocomposite fibers were prepared from chitin whiskers (ChWs) as the reinforcing phase and poly(vinyl alcohol) (PVA) as the matrix. Colloidal suspensions of ChWs, obtained by acid hydrolysis of chitin from crab shell, were thoroughly mixed with aqueous PVA. The homogeneous PVA–ChW suspensions were gel‐spun into a methanol coagulating bath. Wide‐angle X‐ray diffraction patterns evidenced the orientation of ChWs along the fiber axis. From differential scanning calorimetry, the crystallinity of the PVA component was found to increase with ChW loading due to the possible dragging of PVA chains adhering to ChWs during vertical extrusion. The non‐isothermal crystallization peak of PVA was observed to shift to lower temperature with ChW loading indicating interfacial interactions between PVA and ChW. Further interaction between PVA and ChW was evidenced by the shifting of the Fourier transform infrared bands of PVA to lower wavenumber and the dynamic tan δ peak, corresponding to α‐relaxation of PVA, shifting to higher temperature. The interaction of ChWs with the matrix PVA yielded a significant enhancement in the mechanical properties of the nanocomposites. Copyright © 2012 Society of Chemical Industry     

Polyvinyl alcohol fuller's earth clay nanocomposite films

Nano fuller's earth was prepared by milling and subsequent sonication of clay. The polyvinyl alcohol (PVA) and PVA ‐Nano clay composite films were prepared by solution casting method. The films were characterized for their structural, mechanical, and thermal properties using electron microscopes (SEM, TEM), Tensile Tester, dynamic mechanical analyzer (DMA), thermo gravimetric analyzer (TGA), and Raman spectroscopy. The nanocomposite films showed improvement in mechanical properties, viscoelastic behavior as well as resistance towards thermal degradation. Uniform distribution of clay due to intimate interaction between clay and polymer appears to be the cause for improved properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of graphene/poly(vinyl alcohol) nanocomposites

Graphene (GE)‐based nanocomposites are emerging as a new class of materials that hold promise for many applications. In this article, we present a general approach for the preparation of GE/poly(vinyl alcohol) (PVA) nanocomposites. The basic strategy involved the preparation of graphite oxide from graphite, complete exfoliation of graphite oxide into graphene oxide sheets, followed by reduction to GE nanosheets, and finally, the preparation of the GE/PVA nanocomposites by a simple solution‐mixing method. The synthesized products were characterized by X‐ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetry, and differential scanning calorimetry analysis. The GE nanosheets were well dispersed in the PVA matrix, and the restacking of the GE sheets was effectively prevented. Because of the strong interfacial interaction between PVA and GE, which mainly resulted from the hydrogen‐bond interaction, together with the improvement in the PVA crystallinity, the mechanical properties and thermal stability of the nanocomposites were obviously improved. The tensile strength was increased from 23 MPa for PVA to 49.5 MPa for the nanocomposite with a 3.25 wt % GE loading. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and dielectric properties of poly(methyl methacrylate)–clay nanocomposite materials

Poly(methyl methacrylate) (PMMA)–clay nanocomposite (PCN) materials were synthesized through in situ intercalative polymerization. A cationic surfactant, [2(dimethylamino)ethyl]triphenylphosphonium bromide, was used as an intercalating agent with pristine Na⁺‐montmorillonite (MMT). The synthesized PCN materials were subsequently investigated by a series of characterization techniques, including wide‐angle powder X‐ray diffraction, Fourier transform IR spectroscopy, transmission electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. Compared to pure PMMA, the PCN materials exhibit higher thermal degradation temperatures and glass‐transition temperatures. The dielectric properties of PCN blending with a commercial PMMA material in film form with clay loading from 0.5 to 5.0 wt % were measured under frequencies of 100 Hz–1 MHz at 35–100°C. Significantly depressed dielectric constants and losses were observed for these PCN‐blending materials. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2175–2181, 2005     

Mechanical properties and structures of dicyanate–clay nanocomposites

Dicyanate–clay nanocomposites comprising a dicyanate resin and a type of organically modified clay were prepared and characterized, and their thermomechanical properties were investigated. The organically modified clay had silicate layers of nanometer size intercalated with an organic modifier, which improved the compatibility between the clay and organic materials, such as dicyanate resins. Dynamic mechanical analysis was performed to investigate the thermomechanical properties of the dicyanate–clay nanocomposites containing various amounts of the clay. The storage modulus of the nanocomposites below their glass‐transition temperatures slightly increased with increasing clay content. The glass‐transition temperature of the dicyanate–clay nanocomposites increased with increasing clay content. The nanostructures of the dicyanate–clay nanocomposites were characterized by transmission electron microscopy and X‐ray diffraction analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2629–2633, 2003     

Effect of compatibilizer and silane coupling agent on physical properties of ethylene vinyl acetate copolymer/ethylene‐1‐butene copolymer/clay nanocomposite foams

In this study an attempt was made to obtain lower density of ethylene‐vinyl acetate copolymer (EVA)/ethylene‐1‐butene copolymer (EtBC) foams without sacrificing mechanical properties. For this purpose EVA/EtBC/clay nanocomposite foams were prepared. To investigate the effect of compatibilizer and silane coupling agent on the physical properties of the EVA/EtBC/clay foams, maleic anhydride‐grafted EtBC (EtBC‐g‐MAH) and the most commonly used silane coupling agent in rubbers, bis(3‐triethoxysilylpropyl) tetrasulfide (Si‐69) were used in the preparation of EVA/EtBC/clay nanocomposite foams. The formation of EVA/EtBC/clay nanocomposite foams was supported by X‐ray diffraction results. And, using a compatibilzer and silane coupling agent, lower density of EVA/EtBC/clay nanocomposite foams were obtained without sacrificing mechanical properties except compression set. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3259–3265, 2006     

Comparative studies of the properties of poly(methyl methacrylate)–clay nanocomposite materials prepared by in situ emulsion polymerization and solution dispersion

A series of polymer–clay nanocomposite (PCN) materials consisting of organic poly(methyl methacrylate) (PMMA) and inorganic montmorillonite (MMT) clay platelets were prepared successfully by the effective dispersion of nanolayers of the MMT clay in the PMMA framework through both in situ emulsion polymerization and solution dispersion. The as‐prepared PCN materials obtained with both approaches were subsequently characterized with wide‐angle powder X‐ray diffraction and transmission electron microscopy. For a comparison of the anticorrosion performance, a PCN material (e.g., 3 wt % clay loading) prepared by in situ emulsion polymerization, showing better dispersion of the clay platelets in the polymer matrix, exhibited better corrosion protection in the form of a coating on a cold‐rolled steel coupon than that prepared by solution dispersion, which showed a poor dispersion of the clay nanolayers according to a series of electrochemical corrosion measurements. Comparative studies of the optical clarity, molecular barrier properties, and thermal stability of samples prepared in both ways, as membranes and fine powders, were also performed with ultraviolet–visible transmission spectroscopy, molecular permeability analysis, thermogravimetric analysis, and differential scanning calorimetry. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1936–1946, 2004     

Preparation of graphene/poly(vinyl alcohol) nanocomposites with enhanced mechanical properties and water resistance

The control and dispersal of graphene nanosheets in polymer hosts are challenges in the development of high‐performance graphene‐based nanocomposites due to the strong interlayer cohesive energy and surface inertia. Here we report a simple and practical approach to synthesize graphene‐reinforced poly(vinyl alcohol) (PVA) composite films by incorporating graphene oxide and graphene into PVA aqueous solution. The resulting nanocomposites revealed increases of up to 212% in tensile strength and 34% in elongation at break with only 0.5 wt% graphene content. Water absorption measurements showed that the water absorption ratio of the graphene/PVA composites decreased from 105.2 to 48.8%, and the barrier properties were obviously improved. Contact angle measurements showed that the composites were hydrophobic (θ > 90°) in contrast to the highly hydrophilic (θ < 90°) pure PVA. Copyright © 2011 Society of Chemical Industry     

Poly(sodium 4‐styrene sulfonate) and poly(2‐acrylamido glycolic acid) polymer–clay ion exchange resins with enhanced mechanical properties and metal ion retention

This research presents the synthesis of novel nanocomposite ion exchange resins based on poly(sodium 4‐styrene sulfonate) and poly(2‐acrylamido glycolic acid). Nanocomposites were synthesized by in situ radical polymerization using organic modified montmorillonite as filler and different clay contents. Loaded resins showed improvements in mechanical properties compared with unloaded resins: specifically, when the nominal montmorillonite content was 2.5 wt%, poly(sodium 4‐styrene sulfonate) nanocomposite increased its shear modulus from 323 to 910 Pa and doubled its elastic recovery ratio, and the yield point was almost 20 times higher than for unloaded resins. In the case of metal ion retention, the effect of pH and clay content were studied for Cd(II), Pb(II), Cu(II), Cr(III) and Al(III) by a batch procedure. Results showed high efficiency, reaching over 80% after only 1 h of contact. Poly(2‐acrylamido glycolic acid) presented a higher pH dependence than poly(sodium 4‐styrene sulfonate). In addition, it was observed that montmorillonite contributes to retention capacity from the increase in distribution coefficients for loaded resins compared with unloaded resins. Copyright © 2011 Society of Chemical Industry     

Mechanical and barrier properties of poly(lactic acid) films coated by nanoclay–ink composition

In this study, poly(lactic acid) (PLA) films were coated by an ink formulation containing nanoclay dispersed with ultrasonic homogenization for 20 min. Mechanical and barrier properties of the coated films were evaluated according to clay type and concentration. PLA films coated by ink formulations containing Cloisite 30B displayed the best mechanical and barrier properties in six types of nanoclays. PLA films coated by Cloisite 30B‐containing ink varying in clay concentration were investigated. Tensile strength and elongation at break of these coated films were improved in 1% Cloisite 30B. Oxygen permeability decreased significantly upon the addition of clay levels up to 1% and slightly decreased with further increases in the amount of the clay. The value of water vapor permeability also decreased depending on the increases of clay (0%–20%). When the clay content in the sample was 2.0%, the surface of coated PLA films displayed aggregation visible using film emission scanning electron microscopy. X‐ray diffractometry and transmission electron microscopy indicated that a mixture of exfoliated and intercalated structure was formed with addition of 1% (w/w) Cloisite 30B to the ink after ultrasonication. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and properties of (BATB–ODPA) polyimide–clay nanocomposite materials

A series of polymer–clay nanocomposite (PCN) materials consisting of 1,4‐bis(4‐aminophenoxy)‐2‐tert‐butylbenzene–4,4′‐oxydiphthalic anhydride (BATB–ODPA) polyimide (PI) and layered montmorillonite (MMT) clay were successfully prepared by an in situ polymerization reaction through thermal imidization up to 300°C. The synthesized PCN materials were subsequently characterized by Fourier‐Transform infrared (FTIR) spectroscopy, wide‐angle powder X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of material composition on thermal stability, mechanical strength, molecular permeability and optical clarity of bulk PI and PCN materials in the form of membranes were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), molecular permeability analysis (GPA) and ultraviolet‐visible (UV/VIS) transmission spectra, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1072–1079, 2004     

Preparation and characterization of poly(vinyl alcohol) nanocomposites made from cellulose nanofibers

A method using a combination of ball milling, acid hydrolysis, and ultrasound was developed to obtain a high yield of cellulose nanofibers from flax fibers and microcrystalline cellulose (MCC). Poly(vinyl alcohol) (PVA) nanocomposites were prepared with these additives by a solution‐casting technique. The cellulose nanofibers and nanocomposite films that were produced were characterized with Fourier transform infrared spectrometry, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. Nanofibers derived from MCC were on average approximately 8 nm in diameter and 111 nm in length. The diameter of the cellulose nanofibers produced from flax fibers was approximately 9 nm, and the length was 141 nm. A significant enhancement of the thermal and mechanical properties was achieved with a small addition of cellulose nanofibers to the polymer matrix. Interestingly, the flax nanofibers had the same reinforcing effects as MCC nanofibers in the matrix. Dynamic mechanical analysis results indicated that the use of cellulose nanofibers (acid hydrolysis) induced a mechanical percolation phenomenon leading to outstanding and unusual mechanical properties through the formation of a rigid filler network in the PVA matrix. X‐ray diffraction showed that there was no significant change in the crystallinity of the PVA matrix with the incorporation of cellulose nanofibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Glycerol‐plasticized spirulina–poly(vinyl alcohol) films with improved mechanical performance

Spirulina–poly(vinyl alcohol) (PVA)–glycerol (SPG) films with improved mechanical performance, especially tensile strength (TS) and the elongation at break (EAB), are fabricated by a casting method. The integrity, color, solubility, microstructure, thermal properties, tensile strength, and compatibility of the SPG films are assessed. SPG films became smooth, homogeneous, and flexible after plasticizing with glycerol. The presence of PVA and hydrogen bonding of PVA with glycerol and spirulina protein improves the water resistance of SPG films by decreasing water absorption of spirulina protein and decreasing water diffusion through the films. The amount of carbonaceous residues decreases from 31% to 14% because of the co‐pyrolysis of spirulina, PVA, and glycerol. TS increases from 2.5 to 26 Mpa and modulus from 53 to 610 Mpa with increasing PVA content. Glycerol enhances film flexibility and EAB up to 50%. Spirulina can be composited with hydrophilic polymers to fabricate compatible, processable and thermally recyclable films with desirable mechanical performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44842.     

Styrene–butadiene rubber/cellulose II/clay nanocomposites prepared by cocoagulation—mechanical properties

In this work, nanocomposites of styrene butadiene rubber (SBR), cellulose II, and clay were prepared by cocoagulation of SBR latex, cellulose xanthate, and clay aqueous suspension mixtures. The incorporated amount of cellulose II was 15 phr, and the clay varied from 0 to 7 phr. The influence of cellulose II and clay was investigated by rheometric, mechanical, physicochemical, and morphological properties. From the analysis of transmission electron microscopy (TEM), dispersion in nanometric scale (below 100nm) of the cellulosic and mineral components throughout the elastomeric matrix was observed. XRD analysis suggested that fully exfoliated structure could be obtained by this method when low loading of silicate layers (up to 5 phr) is used. The results from mechanical tests showed that the nanocomposites presented better mechanical properties than SBR gum vulcanizate. Furthermore, 5 phr of clay is enough to achieve the best tensile properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Polymeric thermal actuation using laminates based on polymer–clay nanocomposites

Polymer and polymer–clay nanocomposite laminates were prepared as transparent thermal actuators with possible uses in automatic aeration and ventilation or as thermal switches. Low levels of smectite clay addition reduced the thermal expansion coefficient of poly(methyl methacrylate) (PMMA) but retained optical clarity and reduced water absorption. X‐ray diffraction and transmission electron microscopy were used to confirm the formation of PMMA–clay nanocomposites, and dynamic mechanical analysis was used to measure the coefficients of thermal expansion. The experimental values of the radius of curvature of the laminates from cantilever bending tests were in good agreement with the theoretical predictions for composite bars with only 4 wt % (nominally 1.3 vol %) mineral reinforcement. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Surface and electrical characteristics of poly(amide imide)–poly(dimethylsiloxane) nanocomposites

A series of poly(amide imide)–poly(dimethylsiloxane) (PDMS) nanocomposites were fabricated through the reaction of poly(amide imide), epoxysilane (coupling agent), and diethoxydimethylsilane (DEDMS) via a sol–gel process. Nanocomposite films were obtained through the hydrolysis and condensation of DEDMS in poly(amide imide) solutions. The existence of the condensation product of DEDMS in the poly(amide imide) matrix was confirmed with Fourier transform infrared (FTIR). The concentration of PDMS on the surface of the poly(amide imide) matrix was observed through a comparison of FTIR and attenuated total reflection spectra. The contact angle of the poly(amide imide)–PDMS composites increased more than 40° with respect to that of pure poly(amide imide). The alternating‐current (ac) breakdown strength was obtained through the measurement of the ac breakdown voltage at the temperature of liquid nitrogen. As the PDMS concentration in poly(amide imide) increased, the characteristics of the insulation breakdown improved greatly. The best ac breakdown strength was observed in a poly(amide imide)–epoxysilane (30 wt %) nanocomposite with 30 wt % PDMS. The samples at the temperature of liquid nitrogen were brittle, as in a glassy state. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 342–347, 2004     

Poly(vinyl alcohol)/chitosan/honey/clay responsive nanocomposite hydrogel wound dressing

Many efforts have been made to develop modern wound dressings to overcome limitations of traditional ones. Smart nanocomposite hydrogels are appropriate candidates. In this work, a novel responsive nanocomposite hydrogel based on poly(vinyl alcohol)/chitosan/honey/clay was developed and evaluated as a novel wound dressing. The morphology and properties of synthesized nanocomposite hydrogels loaded with honey as a drug model were investigated. The exfoliated morphology of nanocomposite was confirmed by X‐ray diffractometry. Swelling studies were performed at 20 and 37 °C at various pH. The results showed that swelling increased as a result of temperature rise and maximum swelling occurred at a pH of 2. In vitro release of honey was also studied at the same conditions. Corresponding results indicated faster honey release rate at higher pH values. MTT results exhibited no cytotoxicity in nanocomposite hydrogel system. Investigation of antibacterial activity revealed more than 99% antibacterial activity for proposed system. In vivo results confirmed the wound healing ability of developed system. Generally, appropriate properties of proposed system made it ideal in wound dressing applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46311.     

Thermal and mechanical behaviors of poly(vinyl alcohol)–lactose blends

Thermal and mechanical behaviors of poly(vinyl alcohol) (PVA)–lactose blends were studied by differential scanning calorimetry, thermal gravimetric analysis, and stress–strain analysis. The increase in glass transition temperature of the PVA–lactose blends with lactose contents suggests the formation of hydrogen‐bonded PVA–lactose complex in the PVA matrix. The hydrogen bonding interactions can improve thermal and mechanical properties of the blends. Results of this study demonstrate that lactose, a byproduct of dairy industry, can be used directly and in substantial quantity (33%) as a modifier to enforce the physical properties of PVA. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 929–935, 2002     

Adhesion and permeability of polyimide–clay nanocomposite films for protective coatings

A polyimide (PI)–clay nanocomposite was prepared from a solution of poly(amic acid), a precursor of 2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]propane dianhydride and p‐phenylenediamine, and dodecylamine–montmorillonite. Fourier transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction, and atomic absorption spectroscopy were used to verify the incorporation of the modifying agents into the clay structure and the intercalation of the modified clay into the PI matrix. Both PI and PI–clay films were subsequently prepared by solution casting. The gas permeability, resistivity, and adhesion properties were determined. In the case of gas permeability, only a 3 wt % addition of clay reduced oxygen permeability to less than half that of unfilled PI. Furthermore, this hybrid showed an improvement in electrical resistivity because of the prevention of electrical tree growth by clay particles. More importantly, adhesion between the films and silicon increased with increasing clay content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2875–2881, 2003