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1.
A series of polymer–clay nanocomposite (PCN) materials that consisted of poly(styrene‐co‐acrylonitrile) (PSAN) and layered montmorillonite (MMT) clay were successfully prepared by effectively dispersing the inorganic nanolayers of MMT clay into the organic PSAN matrix by a conventional in situ thermal polymerization. First of all, organic styrene and AN monomers at a specific feeding ratio were simultaneously intercalated into the interlayer regions of organophilic clay hosts and followed by a typical free‐radical polymerization with benzyl peroxide as initiator. The as‐synthesized PCN materials were subsequently characterized by FTIR spectroscopy, wide‐angle powder X‐ray diffraction, and transmission electron microscopy. The as‐prepared PCN materials, in the form of coatings, incorporated with low clay loading (e.g., 1 wt %) on cold‐rolled steel, were found to be much superior in corrosion protection over those of bulk PSAN based on a series of standard electrochemical measurements of corrosion potential, polarization resistance, and corrosion current in 5 wt % aqueous NaCl electrolyte. Molecular weights of PSAN extracted from PCN materials and bulk PSAN were determined by gel permeation chromatography with THF as eluant. Effects of the material composition on the molecular barrier and thermal stability of PSAN along with PCN materials, in the form of both membrane and fine powder, were also studied by molecular permeability analysis, differential scanning calorimetry, and thermogravimetric analysis, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2269–2277, 2004  相似文献   

2.
Effect of clay on mechanical, thermal, moisture absorption, and dielectric properties of polyimide‐clay nanocomposites was investigated. Nanocomposites of polyimide (ODA‐BSAA) hybridized with two modified clay (PK‐802 and PK‐805) were synthesized for comparison. The silicate layers in the polymer matrix were intercalated/exfoliated as confirmed by wide‐angle X‐ray diffraction and transmission electron microscopy. Thermal stability, moisture absorption, and storage modulus for these nanocomposites are improved as hybridized clay increases. Reduced dielectric constants due to the hybridization of layered silicates are observed at frequencies of 1 kHz–1 MHz and temperatures of 35–150°C. The tetrahedrally substituted smectite (PK‐805) resulted in higher mechanical strength and dielectric constants than those of octahedrally substituted smectite (PK‐802), which could be attributed to their stronger ionic bonding between clay layer and polymer matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 318–324, 2007  相似文献   

3.
The polymer nanocomposite films (PNC) with varying amounts of organically modified sodium montmorillonite (DMMT) clay in poly(methyl methacrylate) (PMMA) based polymer matrix were prepared by solution cast technique. Dielectric measurements were carried out on these films as a function of frequency at 30°C and 100°C. The addition of clay significantly improved the ionic conductivity. Transport parameters, such as the diffusion coefficient (D), number density (n) and mobility (μ) of charge carriers were determined using a new approach, which is based on impedance spectroscopy. The temperature‐dependent dc conductivity, relaxation and mobility plots obey the Arrhenius rule. The results suggest that the higher ionic conductivity of these PNC films at elevated temperature is not only due to increased mobility of ions, but it is accompanied by a significant increase in carrier concentration. Analysis of DSC thermogram reveals a very high percentage of amorphous content for all samples. A good correlation among dielectric permittivity, carrier concentration, mobility and ionic conductivity has also been observed. POLYM. ENG. SCI., 58:220–227, 2018. © 2017 Society of Plastics Engineers  相似文献   

4.
Poly(styrene‐co‐butadiene) rubber (SBR) and polybutadiene rubber (BR)/clay nanocomposites have been prepared. The effects of the incorporation of inorganically and organically modified clays on the vulcanization reactions of SBR and BR were analysed by rheometry and differential scanning calorimetry. A reduction in scorch time (ts1) and optimum time (t95) was observed for both the rubbers when organoclay was added and this was attributed to the amine groups of the organic modifier. However, ts1 and t95 were further increased as the clay content was increased. A reduction in torque value was obtained for the organoclay nanocomposites, indicating a lower number of crosslinks formed. The organoclays favoured the vulcanization process although the vulcanizing effect was reduced with increasing clay content. The tensile strength and elongation of SBR were improved significantly with organoclay. The improvement of the tensile properties of BR with organoclay was less noticeable than inorganic‐modified clay. Nevertheless, these mechanical properties were enhanced with addition of clay. The mechanical properties of the nanocomposites were dependent on filler size and dispersion, and also compatibility between fillers and the rubber matrix. Copyright © 2004 Society of Chemical Industry  相似文献   

5.
Polystyrene‐clay nanocomposite (PsCN) materials were synthesized and their properties of crystallinity, thermal behavior, and dielectric characteristics were investigated. A polymerizable cationic surfactant, [2‐(dimethylamino)ethyl]triphenylphonium bromide, was used for the intercalation of montmorillonite (MMT). The organophilic MMT was prepared by Na+‐exchanged MMT and ammonium cations of a cationic surfactant in an aqueous medium. Organophilic styrene monomers were intercalated into the interlayer regions of organophilic clay hosts followed by a free‐radical polymerization. Exfoliation to 2 wt % MMT in the polystyrene (PS) matrix was achieved as revealed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal properties by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were also studied. The dielectric properties of PsCNs in the form of film with clay loading from 1.0 to 5.0 wt % were measured under frequencies of 100 Hz–1 MHz at 25–70°C. A decreased dielectric constant and low dielectric loss were observed for PsCN materials. The dielectric response at low frequency that originated from dipole orientation was suppressed due to the intercalation of clay materials. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1368–1373, 2004  相似文献   

6.
A series of new Polypropylene (PP)–clay blends, containing 5 wt % clay, were prepared by melt compounding with maleic anhydride grafted poly(ethylene‐co‐octene) (MAH‐g‐POE) as the compatibilizer by varying its content from 0 to 20 wt %. The effect of MAH‐g‐POE on the PP–clay miscibility was examined by X‐ray diffraction (XRD), scanning electronic microscope (SEM) observation, differential scanning calorimeter (DSC) analysis, dynamic mechanical thermal analysis (DMTA), and rheological testing in sequence. The results showed that the addition of MAH‐g‐POE could improve the dispersion of clay layers in PP matrix and promoted the interaction between PP molecules and clay layers. At 10 wt % MAH‐g‐POE, the PP–clay blend exhibited a highest value of Tc,onset and Tg as well as a biggest melt storage modulus (G′), indicating the greatest PP–clay interaction. On the other hand, improved toughness and stiffness coexisted in blends with 5–10 wt % loading of MAH‐g‐POE. In view of SEM and DMTA observations, MAH‐g‐POE was well miscible with the PP matrix, even with the concentration up to 20 wt %. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2558–2564, 2006  相似文献   

7.
Nanocomposites of natural rubber (NR) and pristine clay (clay) were prepared by latex mixing, then crosslinked with phenolic resin (PhOH). For comparative study, the PhOH‐crosslinked neat NR was also prepared. Influence of clay loading (i.e., 1, 3, 5, and 10 phr) on mechanical properties and structural change of PhOH‐crosslinked NR/clay nanocomposites was studied through X‐ray diffraction (XRD), transmission electron microscopic (TEM), wide‐angle X‐ray diffraction (WAXD), tensile property measurement, and Fourier transform infrared spectroscopy (FTIR). XRD and TEM showed that the clay was partly intercalated and aggregated, and that the dispersion state of clay was non‐uniform at higher clay loading (>5 phr). From tensile test measurement, it was found that the pronounced upturn of tensile stress was observed when the clay loading was increased and a maximum tensile strength of the PhOH‐crosslinked NR/clay nanocomposites was obtained at 5 phr clay. WAXD observations showed that an increased addition of clay induced more orientation and alignment of NR chains, thereby lowering onset strain of strain‐induced crystallization and promoting crystallinity of the NR matrix during tensile deformation. FTIR investigation indicated a strong interfacial adhesion between NR matrix and clay filler through a phenolic resin bridge. This suggested that the PhOH did not only act as curative agent for crosslinking of NR, but it also worked as coupling agent for promoting interfacial reaction between NR and clay. The presence of strong interfacial adhesion was found to play an important role in the crystallization process, leading to promotion of mechanical properties of the PhOH‐crosslinked NR/clay nanocomposites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43214.  相似文献   

8.
This work discloses a novel one‐pot preparation method of polypropylene (PP)/clay nanocomposites with high degree of clay delamination and improved thermal, mechanical and rheological properties. The in situ simultaneous synthesis of carboxylate clay from native clay and ionomer of PP‐graft maleic anhydride (PP‐g‐MA) through trihydrate sodium acetate addition, combined with water injection in the extrusion process, appears to be a valuable alternative to the use of organoclay for producing PP/PP‐g‐MA/clay nanocomposites. The influence of PP‐g‐MA graft content, and of its ionomer form, onto the clay dispersion has been especially investigated. PP‐g‐MA of low graft content is compared to a home‐made highly grafted PP‐g‐MA synthesized in the presence of N‐bromosuccinimide (NBS). The nanocomposites prepared by combining the use of NBS‐mediated PP‐g‐MA, trihydrate sodium acetate and water injection exhibit the highest clay dispersion. Thermal, rheological, and mechanical properties of the nanocomposites have been measured. POLYM. COMPOS., 36:644–650, 2015. © 2014 Society of Plastics Engineers  相似文献   

9.
A series of polypropylene/maleic anhydride grafted polypropylene octane elastomer (MAH‐g‐POE)/clay (PPMC) nanocomposites were prepared with a novel compatilizer MAH‐g‐POE and different contents of octadecyl amine modified montmorillonite, and the effects of clay contents on the dynamic mechanical and rheological properties of these PPMC composites were investigated. With clay content increasing, the characteristic X‐ray diffraction peak changed from one to two with intensity decreasing, indicating the decreasing concentration of the intercalated clay layers. The gradual decrease of crystallization temperature of PPMC composites with the increase of clay loading should be attributed to the preferred intercalation of MAH‐g‐POE molecules into clay interlayer during blending, which is also reflected by scanning electron microscopy observations. By evaluating the activation energy for the glass transition process of MAH‐g‐POE and polypropylene (PP) in the PPMC composites, it is found that clay intercalation could cause the restriction effect on the glass transition of both MAH‐g‐POE and PP, and this restriction effect appears stronger for PP and attained the highest degree at 5 wt % clay loading. The melt elasticity of PP could be improved apparently by the addition of MAH‐g‐POE, and 5 wt % clay loading is enough for further enhancing the elastic proportion of PP. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

10.
A hybride polymer–clay nanocomposite supported dichromate reagents was prepared. Direct interaction of poly(styrene‐co‐N‐methyl‐4‐vinylpyridinium) iodide with sodium montmorillonite (MMT) through ion exchange between sodium cations in MMT and pyridinium ions in the copolymer afforded a polymer–clay nanocomposite (3). The resulting nanocomposite was reacted with potassium dichromate to form the nanocomposite‐supported reagents (4). The structure of the resulting nanocomposite was characterized by elemental analysis, infrared spectroscopy, X‐ray diffraction and transmission electron microscopy. The dispersion of the MMT particles in the polymer matrix was confirmed using scanning electron microscopy. X‐ray mapping for silicon in the nanocomposite revealed uniform distribution of Si in the polymer matrix. The effectiveness of these materials has been tested for oxidation of saturated primary, secondary and benzylic alcohols to their corresponding aldehydic and ketonic compounds in addition to oxidation of quinol to the corresponding quinone. Importantly, there is almost no formation of side‐product of this process. POLYM. COMPOS., 36:2066–2075, 2015. © 2014 Society of Plastics Engineer  相似文献   

11.
A wide range of process parameters regulate the final morphology achieved in layered silicate based polymer nanocomposites. This study deals with the optimization of process variables to improve the matrix formulation. A three‐factor, three‐level Box‐Behnken design with compatibilizer concentration (X1), clay concentration (X2), and screw speed (X3) as the independent variables were selected for the study. The dependent variable was mechanical property of the final nanocomposites. Maleic anhydride grafted polypropylene (PP‐g‐MA) compatibilizer and organoclay (Cloisite 15A) was melt blended with polypropylene separately in a corotating twin screw extruder. The clay was modified with fluorescent dye Nile Blue A Perchlorate (NB) and the adsorbed dye content in the clay gallery was estimated by using UV‐spectrophotometric method. The Minitab‐15 software was used for analysis of the results obtained. Optimum compositions for better dispersion were achieved from contour plots and response surface methodology. It was supported by a unique fluorescence spectrophotometry along with transmission electron microscopy and X‐ray diffraction technique. An intensity ratio close to unity showed a better exfoliated morphology. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

12.
This study focuses on the degree of dispersion and structural development of organomodified MMT clay (OMMT) during processing of polypropylene clay nanocomposites using both conventional and nonconventional characterization techniques. PP‐g‐MA and Cloisite 15A were melt blended with three different grades of PP separately in a micro‐twin screw compounder at selected screw speed and temperature. The clay was modified with fluorescent dyes and the adsorbed dye content in the clay gallery was estimated by using UV‐spectrophotometric method. The effects of residence time and molecular weight of the PP matrix on the clay dispersion were studied. The extent of dispersion and exfoliation of the clay in polymer matrix determined from the torque versus time data obtained from microcompounder. It was further supported by XRD, SEM, TEM, and DSC analysis. Offline dielectric and fluorescence spectrophotometric studies were also carried out. Changes in dielectric constant and dielectric loss with both frequency and temperature yielded quantitative information about the extent of clay exfoliation and intercalation in the polymer matrix. It was observed that with an increase in MFI (decrease in molecular weight) and mixing time, the extent of clay dispersion and exfoliation were also improved due to easy diffusion of polymer chains inside clay gallery. POLYM. COMPOS., 31:2007–2016, 2010. © 2010 Society of Plastics Engineers  相似文献   

13.
A study to investigate matrix properties and their interaction with loaded nanoclay was designed under controlled clay dispersion. Metallocene polyethylene grafted vinyltriethoxy silane (mPE‐g‐silane) was served as the matrix, with or without silane crosslinking (grafting and post crosslinking with catalyst versus only grafting without catalyst), to assess the strength of commercial organoclay (20A)‐filled nanocomposites prepared via a melt mixing. According to X‐ray diffraction and transmission electron microscopy analyses, all nanocomposites achieved similar dispersion degrees at specific clay contents mainly due to the silane interaction with the dispersed clay via hydrogen bonding and/or chemical bonding. Chemical bonding of grafted silane with clay was inferred based on the slightly higher crosslinking degree with increasing clay content for crosslinked cases. For uncrosslinked cases, the crosslinking degree was virtually zero regardless of clay content. The dynamic mechanical properties revealed enhanced interaction between mPE‐g‐silane and clay with increasing clay content based on the increased glass transition temperatures. Young's modulus of nanocomposites with crosslinked cases showed higher values in comparison with uncrosslinked cases at a specific clay content, indicating the significance of matrix crosslinking effect and the effective interfacial interaction between silane and clay especially at higher clay content. To the authors' best knowledge, this is the first study which generally maintains similar clay dispersions through the effect of uncrosslinking (only grafting) and crosslinking (grafting and post crosslinking), and then probes the effect of matrix properties and interfacial interactions at the large deformation state (tensile test) and small deformation state (cutting test). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

14.
A series of superabsorbent composites were prepared from acrylic acid (AA), acrylamide (AM), and Cloisite® 30B by aqueous solution polymerization technique using ammonium peroxodisulfate (APS) as initiator. The interaction of the organically modified nanoclay with PAA‐co‐PAM copolymer was verified by FTIR, whereas the morphology of the composite was studied by Scanning Electron Microscopy (SEM). The water absorbency in deionized water and saline water of the synthesized nanohydrogels was measured by calculating their percentage swelling ratio. The effects of copolymerization, monomer ratio, clay content, and temperature on the water absorbency were studied. The results indicated a considerable increase in swelling ratio by proper monomer proportion and incorporation of optimum clay percentage into the copolymer matrix. It was found that the nanohydrogel acquired highest water absorbency with 2% clay loading. The reswelling ability and water retention capacity of the PAA‐co‐PAM hydrogel and PAA‐co‐PAM/clay nanohydrogel were also measured. The water absorbency was found to increase after each reswelling for which it may be useful as recyclable superabsorbent material. The results of water retention capacity of the nanohydrogel were also encouraging and find application in agriculture, especially in drought‐prone areas. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

15.
Polymer nano‐composites made with a matrix of anhydride‐cured diglycidyl ether of bisphenol A (DGEBA) and reinforced with organo‐montmorillonite clay were investigated. A sonication technique was used to process the epoxy/clay nano‐composites. The thermal properties of the nano‐composites were measured with dynamic mechanical analysis (DMA). The glass transition temperature Tg of the anhydride‐cured epoxy was higher than the room temperature (RT). For samples with 6.25 wt% (4.0 vol%) of clay, the storage modulus at 30°C and at (Tg + 15)°C was observed to increase 43% and 230%, respectively, relative to the value of unfilled epoxy. The clay reinforcing effect was evaluated using the Tandon‐Weng model for randomly oriented particulate filled composites. Transmission electron microscopy (TEM) examination of the nano‐composites prepared by sonication of clays in acetone showed well‐dispersed platelets in the nano‐composites. The clay nano‐platelets were observed to be well‐intercalated/expanded in the anhydride‐cured epoxy resin system. POLYM. COMPOS., 26:42–51, 2005. © 2004 Society of Plastics Engineers.  相似文献   

16.
Isotactic, atactic, and syndiotactic poly(methyl methacrylates) (PMMAs) (designated as iPMMA, aPMMA, and sPMMA) with approximately the same molecular weight were mixed separately with poly(styrene‐co‐acrylonitrile) (abbreviated as PSAN) containing 25 wt % of acrylonitrile in tetrahydrofuran to make three polymer blend systems. Differential scanning calorimetry (DSC) was used to study the miscibility of these blends. The results showed that the tacticity of PMMA has a definite impact on its miscibility with PSAN. The aPMMA/PSAN and sPMMA/PSAN blends were found to be miscible because all the prepared films were transparent and showed composition dependent glass transition temperatures (Tgs). The glass transition temperatures of the two miscible blends were fitted well by the Fox equation, and no broadening of the glass transition regions was observed. The iPMMA/PSAN blends were found to be immiscible, because most of the cast films were translucent and had two glass transition temperatures. Through the use of a simple binary interaction model, the following comments can be drawn. The isotactic MMA segments seemed to interact differently with styrene and with acrylonitrile segments from atactic or syndiotactic MMA segments. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2894–2899, 1999  相似文献   

17.
Polyamide‐11 (PA11)/clay nanocomposites were prepared by in situ intercalative polymerization. The crystal morphology and crystallization kinetics of these nanocomposites were investigated via polarized light microscopy (PLM), small‐angle laser scattering (SALS) and differential scanning calorimetry (DSC). PA‐11 can crystallize into well‐formed spherulites, while only very tiny crystallites were observed by PLM and SALS for the nanocomposites. Both isothermal and non‐isothermal crystallization methods were employed to investigate the crystallization kinetics by DSC. Both techniques showed an increased crystallization rate with the addition of clay. However, the Avrami exponent decreased with the addition of clay in isothermal crystallization but showed a wide range of values depending on the cooling rate in the non‐isothermal crystallization. The changes in crystal morphology and crystallization kinetics can be understood as being due to the ‘supernucleating’ effect of the nanodispersed clay layers. Copyright © 2004 Society of Chemical Industry  相似文献   

18.
Polystyrene–clay nanocomposite (PsCN) materials have been prepared by a free radical polymerization process. Montmorillonite (MMT), modified by two different organics, was investigated: one contains a short chain and three benzyl groups on the ammonium ion (DAETPB), while the other contains a long chain (HTAC). The organic modification determines the extent of exfoliation or intercalation of the materials. Exfoliation is more likely to occur using HTAC, as then the gallery of clay has been opened more due to the long chain structure. Exfoliation of MMT in polystyrene (PS) matrix was revealed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed to confirm the increased thermal stability of these PsCN materials. Dielectric properties of polystyrene‐clay nanocomposites, in the form of film with clay loading from 1.0 to 5.0 wt %, were measured under frequencies of 100 Hz~1 MHz at 25~70°C. Decreased dielectric constant and low dielectric loss were observed for PsCN materials. Especially, the decrease of dielectric constant was found to be related to the extent of exfoliation of clay. It is recognized that the confinement effect of clay results in the suppression of the dielectric response of the nanocomposite materials at low frequency. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2402–2410, 2004  相似文献   

19.
Organoclays containing various amounts of stearic acid (SA) were synthesized, and clay/polystyrene‐block‐polybutadiene‐block‐polystyrene triblock copolymer (SBS) intercalated nanocomposites were prepared using organoclays containing SA by melt‐blending. Montmorillonite was the clay used, and both stearylamine and SA were used as surface modifiers. The amount of SA added was 0, 20, 50 and 100% of the cation‐exchange capacity (CEC). In this study, the effects of SA on the microstructure and mechanical properties of the clay/SBS nanocomposites were investigated. In clay/SBS with 100% CEC of SA, although no exfoliation of the clay occurred, the stacked clay layers were uniformly dispersed at the nanometer level (100–800 nm) without agglomeration. Clay/SBSs containing SA exhibited superior mechanical properties compared to clay/SBS without SA. It was found that SA effectively improved the clay dispersion in the SBS matrix and the mechanical properties of the clay/SBSs. Copyright © 2006 Society of Chemical Industry  相似文献   

20.
Vinylester resin‐clay hybrids were prepared by the mixing different types of organically‐modified montmorillonite (OMMT) with vinylester resin (VER) prepolymer, followed by thermal polymerization. VER prepolymer was synthesized from the reaction of diglycidylether of bisphenol‐A (DGEBA) with acrylic acid. Various types of organic ammonium salts have been used as intercalating agents for montmorillonite, including N,N‐dimethyl‐N‐(4‐vinylbenzyl)stearyl ammonium chloride (VSA), N‐allyl‐N,N‐dimethyl‐stearyl ammonium chloride (ASA) and N,N‐dimethyl‐stearyl ammonium chloride (SA). The dispersion of OMMT into VER matrix was studied by XRD, which indicates the dependence of the morphology mainly on the OMMT content. UV–vis spectra of the hybrids were used to give a quantitative value of the effect of OMMT content on the transparency of VER/OMMT hybrid films. Also, the Vickers test has been performed to study the effect of OMMT content on the surface hardness of the hybrid films. In addition, the thermal properties of the hybrids have been characterized by measuring the softening points and thermogravimetric analyses of the hybrids in comparison with the pure resin. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

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