Polymer–montmorillonite clay nanocomposites. Part 1: Complexation of montmorillonite clay with a vinyl monomer

An organo‐clay complex was formed by the exchange reaction of a quaternary ammonium salt of a derivatized styrene monomer with Na⁺‐montmorillonite clay. The binding of the derivatized styrene monomer with the montmorillonite clay was confirmed by FTIR and the diffused reflectance analysis. The increase of the d‐spacing of the derivatized styrene‐N⁺–montmorillonite clay complex to 1.47 nm, measured by X‐ray diffraction, indicates that a monolayer of the monomer is adsorbed between adjacent montmorillonite layers. A molecular modeling of the monomer suggested a benzene ring tilted to the c‐axis of the montmorillonite clay. The carbon content of the styrene‐N⁺–montmorillonite clay of 11.02 % suggested a complete surface coverage of the clay by the monomer and a surface coverage of 0.74 nm² per exchange site of the montmorillonite. Copyright © 2004 Society of Chemical Industry     

Effect of clay on the properties of poly(styrene‐co‐acrylonitrile)–clay nanocomposites

Clay‐dispersed poly(styrene‐co‐acrylonitrile) nanocomposites (PSAN) were synthesized by a free radical polymerization process. The montmorillonite (MMT) was modified by a cationic surfactant hexadecyltrimethylammonium chloride. The structures of PSAN were determined by wide‐angle X‐ray diffraction and FTIR spectroscopy. The dispersion of silicate layers in the polymer matrix was also revealed by transmission electron microscopy (TEM). It was confirmed that the clay was intercalated and exfoliated in the PSAN matrix. The increased thermal stability of PSAN with the addition of clay was observed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The dielectric properties of PSAN were measured in the frequency range 100 Hz to 1 MHz at 35–70°C. It was found that the dielectric constant from the dipole orientation had been suppressed due to the intercalation of clay. The dielectric loss is strongly related to the residual sodium content of clay, which increases as the sodium content increases by the addition of clay. Copyright © 2004 Society of Chemical Industry     

Preparation and characterization of wood/styrene‐acrylonitrile copolymer/MMT nanocomposite

Wood polymer nanocomposite (WPNC) was prepared by impregnating Simul (Salmalia malabarica) wood with styrene‐acrylonitrile copolymer (SAN), glycidyl methacrylate(GMA), and a reactive polymerizable surfactant modified montmorillonite (MMT). The physical and mechanical properties of WPNC were investigated by using XRD, tensile tester, SEM, and FTIR. The polymer loading, dimensional stability, water uptake, mechanical property, and thermal stability were found to improve due to inclusion of MMT. SEM micrographs showed the presence of polymer and MMT into cell wall and cell lumen. FTIR analysis confirmed the presence of MMT and SAN in WPNC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and properties of styrene–ethylene–butylene–styrene block copolymer/clay nanocomposites: I. Effect of clay content and compatibilizer types

BACKGROUND: Polymer/clay (silicate) systems exhibit great promise for industrial applications due to their ability to display synergistically advanced properties with relatively small amounts of clay loads. The effects of various compatibilizers on styrene–ethylene–butylene–styrene block copolymer (SEBS)/clay nanocomposites with various amounts of clay using a melt mixing process are investigated. RESULTS: SEBS/clay nanocomposites were prepared via melt mixing. Two types of maleated compatibilizers, styrene–ethylene–butylene–styrene block copolymer grafted maleic anhydride (SEBS‐g‐MA) and polypropylene grafted maleic anhydride (PP‐g‐MA), were incorporated to improve the dispersion of various amounts of commercial organoclay (denoted as 20A). Experimental samples were analyzed using X‐ray diffraction and transmission electron microscopy. Thermal stability was enhanced through the addition of clay with or without compatibilizers. The dynamic mechanical properties and rheological properties indicated enhanced interaction for the compatibilized nanocomposites. In particular, the PP‐g‐MA compatibilized system conferred higher tensile strength or Young's modulus than the SEBS‐g‐MA compatibilized system, although SEBS‐g‐MA seemed to further expand the interlayer spacing of the clay compared with PP‐g‐MA. CONCLUSION: These unusual results suggest that the matrix properties and compatibilizer types are crucial factors in attaining the best mechanical property performance at a specific clay content. Copyright © 2007 Society of Chemical Industry     

Application of styrene‐acrylonitrile random copolymer–polyarylate block copolymer as reactive compatibilizer for polyamide and acrylonitrile‐butadiene‐styrene blends

Styrene‐acrylonitrile random copolymer (SAN) and polyarylate (PAr) block copolymer were applied as a reactive compatibilizer for polyamide‐6 (PA‐6)/acrylonitrile‐butadiene‐styrene (ABS) copolymer blends. The SAN–PAr block copolymer was found to be effective for compatibilization of PA‐6/ABS blends. With the addition of 3.0–5.0 wt % SAN–PAr block copolymer, the ABS‐rich phase could be reduced to a smaller size than 1.0 μm in the 70/30 and 50/50 PA‐6/ABS blends, although it was several microns in the uncompatibilized blends. As a result, for the blends compatibilized with 3–5 wt % block copolymer the impact energy absorption reached the super toughness region in the 70/30 and 50/50 PA‐6/ABS compositions. The compatibilization mechanism of PA‐6/ABS by the SAN–PAr block copolymer was investigated by tetrahydrofuran extraction of the SAN–PAr block copolymer/PA‐6 blends and the model reactions between the block copolymer and low molecular weight compounds. The results of these experiments indicated that the SAN–PAr block copolymer reacted with the PA‐6 during the melt mixing process via an in situ transreaction between the ester units in the PAr chain and the terminal amine in the PA‐6. As a result, SAN–PAr/PA‐6 block copolymers were generated during the melt mixing process. The SAN–PAr block copolymer was supposed to compatibilize the PA‐6 and ABS blend by anchoring the PAr/PA‐6 and SAN chains to the PA‐6 and ABS phases, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2300–2313, 2002     

Grafting of maleic anhydride onto styrene–butadiene–styrene triblock copolymer using supercritical CO2 as a swelling agent

Grafting of maleic anhydride (MA) onto styrene–butadiene–styrene triblock copolymer (SBS) was carried out by free radical polymerization using supercritical carbon dioxide (SC CO₂) as a solvent of MA and swelling agent of SBS. The effect of various factors such as monomer concentration, initiator concentration, SC CO₂ pressure, and reaction time on grafting ratio was studied. SBS and the product (SBS‐g‐MA) were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). GPC data showed that the molecular weight of SBS‐g‐MA is bigger than that of SBS. DSC testing indicated that the glass transition temperature (T_g) of SBS‐g‐MA is higher than that of SBS. By SEM photo, we can observe that some particles which contain more oxygen atom grew out from the surface of SBS‐g‐MA when grafting ratio reached at 5.6%, and the amount and diameter of particles increased with increasing of grafting ratio. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4425–4429, 2006     

Grafting onto wool. XVI. Graft copolymerization of vinyl monomers by use of TBHP–FAS as redox initiator

Methyl acrylate (MA), methyl methacrylate (MMA), and n-butyl vinyl ether (n-BVE) have been graft-copolymerized onto Himachali wool in an aqueous medium by using tertiary butyl hydroperoxide ferrous ammonium sulfate (TBHP-FAS) redox system at 40°C, 50°C, 60°C, and 70°C for various reaction periods. Percentage of grafting and percent efficiency have been determined as functions of concentration of monomers, molar ratios of [TBHP]/[FAS], time and temperture. Molar ratios of [TBHP]/[FAS] were found to influence grafting of different monomers studied. Chemical evidence indicates that a covalent bond formation occurs between grafted polymeric chain and backbone polymer. The rate of grafting (R_p) and induction period (I_p) of different monomers towards graft copolymerization were determined as function of total initial monomer concentrations. R_p and I_p of n-BVE are independent of total initial monomer concentrations while R_p and I_p of both MA and MMA were found to depend on the total initial monomer concentrations. MA, MMA, and n-BVE were found to differ in reactivity towards grafting onto wool in the presence of (TBHP-FAS) redox system; the following reactivity order was observed: MMA > MA > n-BVE.     

The combination of expandable graphite,organic montmorillonite,and magnesium hydrate as fire‐retardant additives for ethylene–propylene–diene monomer/chloroprene rubber foams

The fire retardancy and flame‐retardant mechanism of expandable graphite (EG), organic montmorillonite (OMMT), and magnesium hydrate (MH) in ethylene‐propylene‐diene monomer/chloroprene rubber (EPDM/CR) foams were investigated. The results indicated that the combination of EG and OMMT remarkably improved the fire‐retardant property compared to the control samples, and better fireproof performance was achieved when MH was used as the third coretardant unit. The structure of the obtained EPDM/CR/OMMT composites was characterized by X‐ray diffraction, and the results showed that the composites had an intercalated nanostructure. The limiting oxygen index, vertical burning test, and cone calorimeter test results showed that the LOI values and UL‐94 rating increased while the second peak of the heat release rates (HRR) decreased within the EG/OMMT system. In particular, the second pHRR disappeared when the EG/OMMT/MH system was used as a flame retardant. Moreover, the results of thermogravimetric analysis showed that the combination of EG and OMMT reduced the thermal‐degradation rates and mass‐loss percentages. Furthermore, observation by scanning electron microscopy revealed that EG and OMMT left over after combustion formed a complete, compact, and rigid charred layer with a mosaic structure of expanded graphite embedded in cortical‐honeycomb layers of OMMT. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44929.     

Preparation of TiO2-pillared montmorillonite as photocatalyst Part I. Microwave calcination, characterisation, and adsorption of a textile azo dye

Two photocatalysts based on TiO₂-pillared intercalated montmorillonite have been prepared by microwave for 10 min at 700 W or by furnace heating at 673 K. Montmorillonite pillaring with TiO₂ increased the basal spacing to 14.7 Å (conventional heating) and 17.6 Å (microwave heating). XRD patterns of both materials showed the presence of 100% anatase with a slightly higher rate of crystallinity obtained through microwave calcination than by conventional heating at 673 K. The BET specific surface area of the microwave prepared photocatalyst (151 m² g^− 1) was 3 fold higher than those of the Degussa TiO₂ P25. At pH = 5.8, the maximum adsorption capacity of Solophenyl red 3BL (a textile azo dye) on the TiO₂-pillared montmorillonite calcined by microwave was 185 mg g^− 1, whereas it was 1.4 and 3 fold lower on the TiO₂-pillared montmorillonite calcined at 673 K, and on the Degussa TiO₂ P25 respectively. The influence of pH on the adsorption of the dye depended on the pH_ZPC of the pillared montmorillonites.     

The use of 1H NMR and UV–vis measurements for quantitative determination of trans/cis isomerization of a photo‐responsive monomer and its copolymer

Photo‐induced trans–cis isomerization of trans‐4‐methacryloyloxyazobenzene and its copolymer with methylmethacrylate, synthesized in this work, were investigated in a polar protic (CDCl₃) and a polar aprotic (DMSO‐d₆) solvent, using ¹H‐NMR_. The results were cross‐correlated with trans–cis isomerization calculated from UV–visible spectra. The kinetics of the photoisomerization reaction of the monomer species under UV light irradiation is described by a simple first order exchange between the trans and cis forms of the monomer. The behavior was found to be similar for both solvents. The cis‐to‐trans reversion in the absence of irradiation is about 3% of the back reaction under irradiation. For the polymer in solution, the behavior was more complicated and is described by the sum of two equilibria, each of first order exchange kinetics of the trans form with two different types of cis isomer in the polymer; a first type of isomerization similar in behavior to that of the monomer and the second type much faster in cis/trans exchange rate. This bikinetic behavior is in agreement with that of the azobenzene moiety in PMMA as a solid phase mixture. The relative proportion of the two rates comprising the bikinetic effect is solvent‐dependent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1103–1112, 2006     

Poly(sulfobetaine)s and corresponding cationic polymers. VIII. Synthesis and aqueous solution properties of a cationic poly(methyl iodide quaternized styrene–n,n‐dimethylaminopropyl maleamidic acid) copolymer

A cationic poly(methyl iodide quaternized styrene–N,N‐dimethylaminopropylmaleamidic acid) copolymer was synthesized through amidoacidification reaction of styrene‐maleic anhydride copolymer with N,N‐dimethylaminopropylamine (ring‐opening reaction). Its properties in various aqueous salt solutions and pH solutions were studied by measurements of reduced viscosity and intrinsic viscosity. The results indicated that the reduced viscosity and intrinsic viscosity of this cationic polyelectrolyte were related to the type and concentration of the added salts and the results also showed a contrary tendency in some salts with monovalent acid groups to polyelectrolyte. At the same time, some salt ions were observed to strongly attract the quaternary ammonium group of the cationic polymeric side chain and resulted in agglomeration of the polymers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1619–1626, 2001     

The effect of polymers on the crystallisation of n-alkanes from solution,part 2. Mode of action of fumarate–vinyl acetate copolymers

The amount of octadecyl fumarate-vinyl acetate (C₁₈FVA) copolymer which co-crystallised with dotriacontane from dodecane solution was measured by infrared and electron spin resonance (ESR) spectroscopy. It was found that the magnitude of the slow-motion component in the composite ESR spectra of the system below its cloud point did not accurately reflect the amount of polymer which had co-crystallised with the dotriacontane. ESR studies of isolated samples of the co-crystallate showed the C₁₈FVA to be less tightly bound than in the bulk polymer, suggesting that the polymer molecules are adsorbed on to the surface of the dotriacontane crystals.