Studies on properties of softwood (Ficus hispida)/PMMA nanocomposites reinforced with polymerizable surfactant-modified nanoclay

Soft wood (Ficus hispida) was chemically modified by impregnation of methyl methacrylate monomer, glycidyl methacrylate (GMA), a cross-linking agent, and montmorillonite (MMT) using catalyst heat treatment. MMT was modified by using a polymerizable surfactant 2-acryloloxy ethyl trimethyl ammonium chloride (ATAC) and a mixture of surfactants ATAC and cetyl trimethyl ammonium bromide (CTAB) in a molar ratio of (1:1). A comparative study on different properties of the prepared wood polymer nanocomposite (WPNC) based on impregnation of intercalating mixture containing MMA/GMA/clay modified by both the surfactants (ATAC and CTAB) and MMA/GMA/clay modified by only surfactant ATAC were done. FTIR, XRD, and TGA studies were employed for the characterization of clay and WPNC. WPNC prepared by using combined surfactant-modified clay along with MMA/GMA exhibited improved dimensional stability, chemical resistance, thermal stability, mechanical properties, and lower water uptake than that of WPNC prepared by using single surfactant-modified clay and MMA/GMA system.     

Synergistic effect of nanoTiO2 and nanoclay on mechanical, flame retardancy, UV stability, and antibacterial properties of wood polymer composites

Wood–polymer nanocomposite (WPNC) based on styrene–acrylonitrile copolymer (SAN), γ-trimethoxy silyl propyl methacrylate-modified TiO₂ nanoparticles, and nanoclay was prepared by impregnation. The flexural, tensile, and flame-retardant properties were improved. UV stability was evaluated by photo-induced weight loss, FTIR, loss in mechanical properties, and scanning electron microscopy. The results showed that UV stability was maximum for wood sample treated with SAN/TiO₂ (0.5 %)/nanoclay (0.5 %). The presence of TiO₂ nanoparticles in WPNC-exhibited antibacterial activity.     

Effect of different crosslinkers on properties of melamine formaldehyde‐furfuryl alcohol copolymer/montmorillonite impregnated softwood (Ficus hispida)

Melamine formaldehyde‐furfuryl alcohol (MFFA) copolymer was prepared and impregnated into softwood Ficus hispida in combination with crosslinking agent and montmorillonite (MMT) under vacuum condition. Different crosslinkers namely n‐methylol acrylamide, (NMA), 2‐hydroxyethyl methacrylate (HEMA) and 1,3‐dimethylol‐4,5‐dihydroxyethyleneurea (DMDHEU) were used for evaluation of properties of the prepared composites. Nuclear magnetic resonance (NMR) and fourier transform infrared spectroscopy (FTIR) studies confirmed the formation of MFFA copolymer, NMA, and DMDHEU crosslinkers. X‐ray diffractometry (XRD) and FTIR studies were used to characterize the nanocomposites. The incorporation of MMT decreased the crystallinity of wood composites as revealed by XRD study. Maximum interaction was found in wood samples treated with MFFA/(NMA+HEMA+DMDHEU)/MMT as shown by FTIR study. The incorporation of MMT into the wood polymer composite was revealed by transmission electron microscopy study. Thermal stability and flammability were checked by thermogravimetric analyzer and limiting oxygen index instrument. Wood treated with MFFA, blended crosslinker and MMT exhibited higher dimensional stability, lower water uptake (%), enhanced chemical resistance, and better mechanical properties (flexural, tensile, and hardness). SEM study indicated the presence of polymer and MMT in the void spaces of wood. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Study on properties of simul wood (Bombax ceiba L.) impregnated with styrene acrylonitrile copolymer, TiO2, and nanoclay

Dimensional stability, thermal, and water repellency are very important properties of wood. In this research, wood polymer nanocomposite (WPNC) has been prepared by impregnation of styrene acrylonitrile copolymer (SAN), ??-trimethoxy silyl propyl methacrylate-modified TiO₂ nanoparticles, nanoclay into simul (Bombex ceiba L.) wood. The characterization of the composites was done by using Fourier transform infrared spectroscopy, X-ray diffractometry, and thermogravimetry. The resultant WPNC exhibited an improvement in water repellency, moisture resistance, dimensional stability, chemical resistance, hardness, and thermal stability. The maximum improvement in all the properties has been observed for the wood sample treated with SAN/TiO₂ (0.5?%)/nanoclay (0.5?%).     

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

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

Effect of montmorillonoite modification and maleic anhydride‐grafted polypropylene on the microstructure and mechanical properties of polypropylene/montmorillonoite nanocomposites

Two types of modified montmorillonite (MMT) were achieved using octadecylamine as the modifying agent by the methods of dry process and wet route. Polypropylene (PP)/MMT nanocomposites were prepared using the melt mixing technique and employing maleic anhydride‐grafted polypropylene (PP‐MA) as the compatibilizer. The modification of montmorillonite was characterized by fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and scanning electron microscope (SEM). The effect of MMT modification and PP‐MA on the microstructure and properties of PP/MMT nanocomposites was investigated by SEM, differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and polarizing microscopy. The results show that organic montmorillonite modified by wet process (WOMMT) has a large d‐spacing increment; whereas montmorillonite modified by dry process (DOMMT) shows little d‐spacing increment. Furthermore, the mechanical properties of composites incorporating WOMMT are better than that containing DOMMT. As a third component, the addition of PP‐MA benefits the formation of exfoliated structure and the dispersion of MMT in PP matrix, and hence, enhances the physical properties of the nanocomposite. With the presence of PP‐MA, the highly dispersed MMT increases the number of spherulite crystals, enhances the melting enthalpy, improves the thermal stability, and induces the desired tiny crazes more effectively. MMT increases the storage modulus (E′) and glass‐transition temperature (T_g) of PP because of the stiffness of MMT layers, but PP‐MA decreases them owing to its high melt flow index, both of which were in favor of improving the physical properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3952–3960, 2013     

Electrospinning fabrication and characterization of poly(vinyl alcohol)/montmorillonite nanofiber mats

Poly(vinyl alcohol) (PVA)/montmorillonite clay (MMT) nanofiber mats have been fabricated by the electrospinning technique. The PVA/MMT nanofiber mats were characterized by X‐ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and mechanical measurements. The study showed that the introduction of MMT results in improvement in tensile strength, and thermal stability of the PVA matrix. XRD patterns and SEM micrographs suggest the coexistence of exfoliated MMT layers over the studied MMT contents. FTIR revealed that there might be possible interaction occurred between the MMT clay and PVA matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polypropylene/organically modified Sabah montmorillonite nanocomposites: Surface modification and nanocomposites characterization

The aim of the work is to extract, purify, and organically modify montmorillonite (MMT) of Lahad Datu, Sabah bentonite. The octadecylamine treated Sabah MMT (S‐OMMT) (2–8 wt%) was then melt blended with polypropylene (PP) and maleated polypropylene (PPgMAH) (10 wt%) via single screw nanomixer extruder followed by injection molding into test samples to examine the mechanical, thermal, and morphological properties of PP/S‐OMMT nanocomposites. Unmodified Sabah MMT (S‐MMT) and commercial grade MMT (Nanomer 1.30P) filled PP nanocomposites were also characterized for comparison purpose. X‐ray diffraction results showed that the interlayer spacing of S‐MMT increased after organic modification as Fourier transform infra‐red and elemental analysis evidenced the presence of octadecylamine. PP/S‐OMMT nanocomposites showed a better dispersion and strength compared to PP/Nanomer 1.30P nanocomposites due to its smaller MMT platelet size. differential scanning calorimetry and Thermogravimetry analysis revealed that the thermal stability and crystallinity of neat PP improved with the addition of all types of MMT. Dynamic mechanical analyzer showed that PP nanocomposites have higher storage modulus (E′) values than the neat PP over the whole temperature range. The new PP/S‐OMMT nanocomposites showed a comparable performance with PP/Nanomer 1.30P nanocomposites exhibiting promising future applications of S‐MMT in polymer/MMT nanocomposites. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Preparation and characterization of carboxymethyl konjac glucomannan/sodium montmorillonite hybrid films

Carboxymethyl konjac glucomannan (CKGM)/ sodium montmorillonite (MMT) hybrid films of various compositions were prepared by casting from a polymer/silicate water suspension. The structure and properties of the hybrid films were investigated by wide angle X‐ray diffraction (WAXD), transmission electron microscopy (TEM), attenuated total reflection infrared spectroscopy (ATR‐IR), differential scanning calorimetry (DSC), and tensile tests. The results from WXRD and TEM indicated that an intercalated CKGM/MMT nanocomposite film was obtained by polymer solution intercalation. WXRD and DSC showed that the high‐T_m crystal phase was induced by the presence of lower MMT loading, but the T_m of the hybrid films became weak with the increase of MMT content due to the polymer confinement. The hybrid films showed higher thermal stability and mechanical properties than that of the neat polysaccharide due to the strong interaction between hydroxyl and carbonyl group of CKGM and the silicate layer of MMT. Furthermore, the degree of swelling of the hybrid films was investigated in acidic buffer solutions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2954–2961, 2007     

Preparation and properties of thermoplastic starch/montmorillonite nanocomposites using N,N‐bis(2‐hydroxyethyl)formamide as a new additive

N,N‐Bis(2‐hydroxyethyl)formamide (BHF) was synthesized efficiently and used as a new additive to prepare thermoplastic starch/montmorillonite (TPS/MMT) nanocomposites. Here, BHF acted as both plasticizer for TPS and swelling agent for MMT. The hydrogen bond interaction among BHF, starch, and MMT was proven by Fourier transform infrared (FTIR) spectroscopy. By scanning electron microscope (SEM), starch granules were completely disrupted. Atomic force microscopy demonstrated that partially exfoliated TPS/MMT nanocomposites were formed. The crystallinity of corn starch, MMT, BHF‐plasticized TPS (BTPS), and TPS/MMT nanocomposites was characterized by X‐ray diffraction (XRD), XRD demonstrated that partially intercalated TPS/MMT nanocomposites were formed. The water resistance of TPS/MMT nanocomposites increased compared with that of pure BTPS. Mechanical properties of BTPS and TPS/MMT nanocomposites were examined. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Structural characterization of LDPE/EVA blends containing nanoclay‐flame retardant combinations

The combination of different types of organo‐modified montmorillonite (MMT) with aluminum hydroxide (aluminum trihydrate—ATH), as a flame retardant system for polyethylene‐ethylene vinyl acetate (LDPE/EVA), blends were studied. Five different types of organically modified montmorillonite clays, each with different modifier, were used. The structural characterization was carried out by X‐ray diffraction (XRD) and scanning electron microscopy in transmission mode (STEM). The mechanical and rheological properties were also evaluated. The XRD analysis showed a clear displacement of the d₀₀₁ signal, which indicates a good degree of intercalation, especially for the MMT‐I28 and MMT‐20, from Nanocor and Southern Clay Products, respectively. The presence of ATH and the compatibilizer did not have any effect on the exfoliation of the studied samples. The thermal stability and flame retardant properties were evaluated by thermogravimetric analysis (TGA), limiting oxygen index (LOI—ASTM D2863), and flammability tests (Underwriters Laboratory—UL‐94). The effect of different compatibilizers on the clay dispersion and exfoliation was studied. The results indicated that the addition of montmorillonite makes it possible to substitute part of the ATH filler content while maintaining the flame retardant requirements. The thermal stability of MMT/ATH‐filled LDPE/EVA blends presented a slight increase over the reference ATH‐filled LDPE/EVA blend. Compositions with higher clay content (10 wt %) showed better physicochemical properties. The increased stability of the higher clay content compositions results from the greater inorganic residual formation; this material has been reported to impart better performance in flammability tests. The mechanical properties and flame retardancy remained similar to those of the reference compound. The reduced ATH content resulted in lower viscosities and densities, facilitating the processing of the polymer/ATH/clay compounds. Extrusion of these compounds produced a lower pressure in the extrusion head and required reduced electrical power consumption. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of montmorillonite/polypyrrole nanocomposite

A novel montmorillonite (MMT)/polypyrrole (PPy) nanocomposite (MPN) with high electrical conductivity and thermal stability has been synthesized via in‐situ polymerization. The surface morphology, characterization, thermal stability, and electrical conductivity have been tested by scanning electron microscopy (SEM), Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and four‐probe methods, respectively. SEM results show that the antenna‐like PPy deposits on the layer surface of MMT. FTIR and XRD analyses show that there is interaction between MMT and PPy. The nanocomposite has high electrical conductivity (4 S/cm), eight orders of magnitude higher than that of pristine MMT. The thermal stability of MPN is higher than the pure PPy as well as the mixture of MMT and PPy (MMP). POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Synthesis of effective poly(4‐vinylpyridine) nanocomposites: in situ polymerization from edges/surfaces and interlayer galleries of clay

Poly(4‐vinylpyridine) (P4VP) nanocomposites have been prepared by using an in situ polymerization method in the presence of organically modified montmorillonite (MMT) clays with a quarternary salt of cocoamine containing a vinyl group, as well as trimethoxy vinyl silane. The nanocomposites were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The desired exfoliated nanocomposite structure was achieved when the MMT modification was conducted in the presence of both modifiers, whereas individual modifications all resulted in intercalated structures. This resultant exfoliated nanocomposite was found to have better thermal stability and dynamic mechanical performance when compared to the other nanocomposites, even with 2 % clay loading. Copyright © 2005 Society of Chemical Industry     

Influence of the type of quaternary ammonium salt used in the organic treatment of montmorillonite on the properties of poly(styrene‐co‐butyl acrylate)/layered silicate nanocomposites prepared by in situ miniemulsion polymerization

Hybrid latices of poly(styrene‐co‐butyl acrylate) were synthesized via in situ miniemulsion polymerization in the presence of 3 and 6 wt % organically modified montmorillonite (OMMT). Three different ammonium salts: cetyl trimethyl ammonium chloride (CTAC), alkyl dimethyl benzyl ammonium chloride (Dodigen), and distearyl dimethyl ammonium chloride (Praepagen), were investigated as organic modifiers. Increased affinity for organic liquids was observed after organic modification of the MMT. Stable hybrid latices were obtained even though miniemulsion stability was disturbed to some extent by the presence of the OMMTs during the synthesis. Highly intercalated and exfoliated polymer‐MMT nanocomposites films were produced with good MMT dispersion throughout the polymeric matrix. Materials containing MMT modified with the 16 carbons alkyl chain salt (CTAC) resulted in the largest increments of storage modulus, indicating that single chain quaternary salts provide higher increments on mechanical properties. Films presenting exfoliated structure resulted in the largest increments in the onset temperature of decomposition. For the range of OMMT loading studied, the nanocomposite structure influenced more significantly the thermal stability properties of the hybrid material than did the OMMT loading. The film containing 3 wt % MMT modified with the two 18 carbons alkyl chains salt (Praepagen) provided the highest increment of onset temperature of decomposition. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electron beam synthesis and characterization of poly(vinyl alcohol)/montmorillonite nanocomposites

Poly(vinyl alcohol) (PVA)/montmorillonite clay (MMT) nanocomposites in the form of films were prepared under the effect of electron beam irradiation. The PVA/MMT nanocomposites gels were characterized by X‐ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and mechanical measurements. The study showed that the appropriate dose of electron beam irradiation to achieve homogeneous nanocomposites films and highest gel formation was 20 kGy. The introduction of MMT (up to 4 wt %) results in improvement in tensile strength, elongation at break, and thermal stability of the PVA matrix. In addition, the intercalation of PVA with the MMT clay leads to an impressive improved water resistance, indicating that the clay is well dispersed within the polymer matrix. Meanwhile, it was proved that the intercalation has no effect on the metal uptake capability of PVA as determined by a method based on the color measurements. XRD patterns and SEM micrographs suggest the coexistence of exfoliated intercalated MMT layers over the studied MMT contents. The DSC thermograms showed clearly that the intercalation of PVA polymer with these levels of MMT has no influence on the melting transitions; however, the glass transition temperature (T_g) for PVA was completely disappeared, even at low levels of MMT clay. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1129–1138, 2006     

In situ compatibilized SAN/LCP blends through reactive copolymers

Styrene–acrylonitrile–glycidyl methacrylate (SAG) copolymers with various contents of glycidyl methacrylate (GMA) were used to compatibilize the incompatible blends of styrene–acrylonitrile (SAN) and a liquid crystalline polymer (LCP). These SAG copolymers contain reactive glycidyl groups that are able to react with the carboxylic acid and/or hydroxyl end groups of the LCP to form the SAG‐g‐LCP copolymers during melt processing. The in situ–formed graft copolymers tend to reside along the interface to reduce the interfacial tension and to increase the interface adhesion. The morphologies of the SAN/LCP blends were examined by using scanning electron microscopy (SEM), where the compatibilized SAN/LCP blends were observed with greater numbers and finer fibrils than those of the corresponding uncompatibilized blends. The mechanical properties of the blends increased after compatibilization. The presence of a small amount (200 ppm) of ethyl triphenylphosphonium bromide (ETPB) catalyst further promotes the graft reaction and improves the compatibilization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3321–3332, 2001     

Solid state NMR characterization and flammability of styrene-acrylonitrile copolymer montmorillonite nanocomposite

This work investigates the melt-processing of styrene-acrylonitrile copolymer (SAN) with organo-modified montmorillonite (MMT) clays and the influence of the clay on mechanical properties and on fire performance of SAN. The nanodispersion of MMT is evaluated qualitatively by X-ray diffraction (XRD) and transmission electronic microscopy (TEM), and quantitatively by solid state nuclear magnetic resonance (NMR). SAN/MMT nanocomposites reveal an intermediate morphology, an intercalated structure with some exfoliation and with the presence of small tactoids, whatever the loading in MMT is. The polymer-clay interfacial area is estimated at 0.5 and the degree of homogeneity characterizing the distribution of MMT platelets is about 40%. The presence of clay in SAN-25 leads to a ‘filler effect’ increasing the stiffness but decreasing tensile strength of the nanocomposites. It also leads to a significant decrease of peak of heat release rate measured by mass loss calorimetry.     

Electrolytic admicellar polymerization of pyrrole on natural rubber/clay nanocomposites

Organic–inorganic composites consisting of natural rubber (NR), polypyrrole (PPy), and sodium montmorillonite (Na‐MMT) were synthesized via electrolytic admicellar polymerization. A constant potential of 9 volts was chosen for the synthesis. The PPy concentration was fixed at 100 mM, and the clay contents were varied from 1 to 7 parts per hundred of rubber (phr). The synthesized nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy (TEM), together with thermal stability (TGA), mechanical properties, and electrical conductivity (σ_dc) studies. The FTIR spectra indicated the characteristic peaks of both PPy and MMT clay and also evidenced a slight interaction between the PPy chain and the clay layers, verifying the success of electrolytic admicellar polymerization. XRD and TEM results pointed out the good dispersion of clay platelets in the polymer matrix, suggesting an exfoliated structure. The morphology of the nanocomposites was greatly dependent on the amount of MMT clay, especially at a 7 phr loading. The initial modulus and tensile strength of the nanocomposites containing the 7 phr loading were about four and two times higher, compared with unfilled NR/PPy, respectively. Thermal stability studies revealed a slight improvement in the decomposition temperature for the PPy component by the clay layers, whereas the opposite trend was found for the NR component. More interestingly, the electrical conductivity of the admicelled rubber increased significantly (～ 19–32 times) with increasing clay contents from 1 to 7 phr, in comparison with unfilled NR/PPy. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Poplar wood‐methylolurea composites prepared by in situ polymerization

Chemical modification of wood is a potential way to obtain high quality wood. In this study, methylolurea was used to modify the polar wood by in situ polymerization. The mechanical properties and dimension stability of the wood‐methylourea composites were investigated, and the modified samples were also characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD). The mechanism of in situ polymerization was presented in graphs. The test results showed that the mechanical properties and dimensional stability of natural wood were improved remarkably. FTIR analysis suggested that the methylolurea polymerized with the active groups of wood cell wall. XRD test showed that the crystallinity of wood increased after modification. Finally, the SEM analysis proved that the good interfacial adhesion of wood modifier between wood fiber and polymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 933‐938, 2013     

Synthesis and characterization of polyurethane/bentonite nanoclay based nanocomposites using toluene diisocyanate

Polyurethanes (PUs) prepolymers blended with bentonite nanoclay and without bentonite nanoclay were prepared by the reaction of toluene-2,4-diisocyanate (TDI) and hydroxyl terminated polybutadiene (HTPB), and the chain was further extended with 1,4-butane diol (1,4-BDO) to get final polyurethane nanocomposites (PUNC). A mixture of polymer and bentonite clay enriched in montmorillonite (MMT) was formed in solution polymerization, in which MMT dispersed depending on interaction of MMT with polymer chains. The molecular structure of the monomers and the prepared PU nanocomposites was confirmed by FTIR. A series of PUNCs were prepared by varying the percent compositions of bentonite nanoclay into the PU matrix. The existence of the clay in to the PU was confirmed by scanning electron microscope (SEM). SEM images verified the good dispersion of the bentonite nanoclay in PU matrix.