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1.
Organic–inorganic hybrid poly(styrene‐co‐butyl acrylate)/organically modified montmorillonite (PSBA/organo‐MMT) latex particles have been prepared by in situ emulsion polymerization. The effects of modifier variety and the level of organo‐MMT have been investigated on the basis of the characteristics and mechanical properties of the resulting hybrid emulsion polymers. Although the more hydrophilic intercalated organic modifiers increased the latex particle size, the hydrophobic ones decreased the particle size. A more heterogeneous copolymer chain intercalation was seen by widespread XRD reflection as the organo‐MMT (organoclay) level increases. The tapping mode atomic force microscopy (AFM) and transmission electron microscopy (TEM) were used to determine the dispersion state of organoclay particles inside the nanocomposite copolymer films. Dynamic mechanical thermal analysis (DMTA) showed that adding the organoclay to the copolymer decreased the maximum loss tangent (tanδ) value and caused the shift to a lower temperature. Interestingly, the incorporation of organoclay decreased the glass storage modulus of the copolymer, while increased the rubbery storage modulus to some extent. In addition, a standard indenter for the nanoscratching of copolymer nanocomposite films was used under low applied loads of 150 and 250 μN. The nanoscratch results showed that incorporation of a 3 wt % hydrophobic organoclay, e.g., Closite15A, in the copolymer matrix enhanced considerably the near‐surface hardness and grooving resistance of the nanocomposite film at room temperature. In fact, copolymer nanocomposite films with higher near‐surface hardness and tanδ curve broadening exhibited more nanoscratch resistance through a specific variety of viscoelastic deformation, which did not create a bigger groove. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

2.
Na‐montmorillonite/polyethyleneimine‐g‐poly(methyl methacrylate) (Na‐MMT/PEI‐g‐PMMA) nanocomposite latexes were prepared by soap‐free emulsion polymerization in the aqueous suspension of Na‐MMT. The exfoliated morphology of the nanocomposites was confirmed by XRD and TEM. With the aim of improving morphology and mechanical properties of natural rubber latex (NRL) films, the synthesized Na‐MMT/PEI‐g‐PMMA nanocomposites were mixed with NRL by latex compounding technology. The results of SEM and AFM analysis showed that the surface of NRL/Na‐MMT/PEI‐g‐PMMA film was smoother and denser than that of pristine NRL film while Na‐MMT was dispersed uniformly on the fracture surface of the modified films, which suggested the good compatibility between NRL and Na‐MMT/PEI‐g‐PMMA. The tensile strength of NRL/Na‐MMT/PEI‐g‐PMMA films was increased greatly by 85% with 10 phr Na‐MMT/PEI‐g‐PMMA when Na‐MMT content was 3 wt % and the elongation at break also increased from 930% to 1073% at the same time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43961.  相似文献   

3.
With some polymerizable small molecules grafting onto the montmorillonite surface, we disposed the clay through in‐situ emulsion polymerization, and the structure of the modified montmorillonites were studied through Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD). The nanocomposites of poly(styrene‐b‐butadiene‐b‐styrene) (SBS)/montmorillonite with excellent mechanical properties were prepared by mixing SBS and the modified montmorillonite on the double rollers at 150°C. The exfoliation of the layered silicates was confirmed by XRD analysis and transmission electron microscopy (TEM) observation. After mechanical kneading of the molten nanocomposites, the exfoliation structure of the silicates is still stable for polystyrene macromolecules grafting onto the silicates. Upon the addition of the modified montmorillonite, the tensile strength, elongation at break and tear strength of the nanocomposites increased from 22.6 MPa to 31.1 MPa, from 608% to 948%, from 45.32 N/mm to 55.27 N/mm, respectively. The low‐temperature point of glass‐transition temperature (Tg) of the products was about −77°C, almost constant, but the high‐temperature point increased from 97°C to 106°C. In addition, the nanocomposites of SBS and modified montmorillonites showed good resistance to thermal oxidation and aging. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers  相似文献   

4.
The present work focuses on the preparation and characterization of organo‐modified fluorohectorite (OFH) clay filled polyoxymethylene (POM) nanocomposites by melt mixing method. The dispersion of OFH clay in the polymer matrix was confirmed by X‐ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM) analysis. The surface properties of the nanocomposites, assessed by contact angle measurements, showed increase in hydrophobicity relative to the neat polymer. From the measured contact angle values, various surface parameters such as total surface free energy, interfacial free energy, work of adhesion, spreading coefficient, and Girifalco‐Good's interaction parameter were calculated. The thermal, mechanical, and dielectric properties of the nanocomposites were found to be improved by the incorporation of OFH clay into the POM matrix. The aging studies of the nanocomposites carried out by immersing the samples in various solvents showed an increase in the retention of mechanical property by the addition of OFH clay into the POM matrix. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers  相似文献   

5.
Poly(amic acid) nanocomposites were synthesized from a dimethylacetamide (DMAc) solution with two organophilic montmorillonites (organo‐MMTs). It was then heated at various temperatures under vacuum, yielding 15–20 um thick films of polyimide/organo‐MMT hybrid with different clay contents (1–8 wt%). Dodecy‐lamine (C12‐) and hexadecylamine (C16‐) were used as aliphatic alkylamines in organo‐MMT. The ultimate strength monotonically increased with increasing clay content in the polymer matrix. Maximum enhancement in the initial modulus was observed for the blends containing 2 wt% clay with two kinds of organo‐clays, and values did not alter significantly with further increases in clay content. Additions of only 2 wt% C12‐ and C16‐MMT to the polyimide were shown to cause 94%‐95% reduction in oxygen gas permeability. This is caused by the barrier properties of the clay layers dispersed in the composite. In general, C16‐MMT is more effective than C12‐MMT in increasing both the tensile property and the gas barrier in a polyimide matrix. Intercalations of the polymer chains in clay were examined through wide‐angle X‐ray diffraction (XRD) and electron microscopies (SEM and TEM).  相似文献   

6.
Hybrids of poly(L ‐lactide)/organophilic clay (PLACHs) have been prepared by a melt‐compounding process using poly(L ‐lactide) (PLLA) and different contents of surface‐treated montmorillonite modified with a dimethyl dioctadecyl ammonium salt. The dispersion structures of clay particles in PLACHs were investigated using wide‐angle X‐ray diffraction and transmission electron microscopy. The solid‐state linear viscoelastic properties for these PLACHs were examined as functions of temperature and frequency. The incorporation of organo‐modified silicate into PLLA matrix enhanced significantly both storage moduli (E′) and loss moduli (E″). The strong enhancement observed in dynamic moduli of PLACHs could be attributed to uniformly dispersed state of the clay particles with high aspect ratio (= length/thickness of clay) and the intercalation of the PLLA chains between silicate layers. Copyright © 2006 Society of Chemical Industry  相似文献   

7.
Surface morphology of monolayers related to solid‐state structure for methacrylate comb copolymers having fluorocarbon and hydrocarbon side‐chains was investigated by X‐ray diffraction (XRD), differential scanning calorimetry, and atomic force microscopy (AFM). From the XRD profiles, two kinds of short spacing peaks were confirmed at 5.0 and 4.2 Å, which assigned the sub‐cells for both side‐chains. Furthermore, two kinds of endothermic peaks, which corresponded to melting peaks of the both side‐chain crystals, appeared in the thermograms. From the AFM observation, it was found that there were hydrogenated domains at a few hundred nanometer diameter in their monolayers, whereas corresponding acrylate copolymer monolayers form the phase‐separated structure at 10–30 nm order scales. POLYM. ENG. SCI., 47:354–364, 2007. © 2007 Society of Plastics Engineers.  相似文献   

8.
Nanocomposites based on organically modified montmorillonites (OMMTs) and sodium montmorillonite (CLO‐Na+) with poly(styrene‐b‐butadiene‐b‐styrene) (SBS) diblock copolymer have been investigated. Solution blending of OMMT suspension in toluene with SBS and subsequent static casting and annealing resulted in transparent films. Final samples were processed by compression molding. The intercalation spacing in the nanocomposites, microphase separation of the SBS, and the degree of dispersion of nanocomposites were investigated by X‐ray diffraction (Wide and small‐angle X‐ray scattering), transmission optical microscopy (TOM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The increase of basal spacing of OMMT in the nanocomposites suggested the intercalation of SBS. The lamellar structure perfection was extensively affected by both OMMT. AFM images and TOM micrographs only showed well dispersed but not exfoliated nanocomposites. On the other hand, TEM showed inserted tactoids into both blocks depending on the surfactant used (stained samples) and the dispersion of those tactoids (unstained samples). Fourier transform infrared spectroscopy indicated only the presence of the OMMT into the SBS. Deviations of the decomposition pathway of pristine SBS with addition of the OMMT were found by thermogravimetric analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

9.
Clay containing polypropylene (PP) nanocomposites were prepared by direct melt mixing in a twin screw extruder using different types of organo‐modified montmorillonite (Cloisite 15 and Cloisite 20) and two masterbatch products, one based on pre‐exfoliated clays (Nanofil SE 3000) and another one based on clay–polyolefin resin (Nanomax‐PP). Maleic anhydride‐grafted polypropylene (PP‐g‐MA) was used as a coupling agent to improve the dispersability of organo‐modified clays. The effect of clay type and clay–masterbatch product on the clay exfoliation and nanocomposite properties was investigated. The effect of PP‐g‐MA concentration was also considered. Composite morphologies were characterized by X‐ray diffraction (XRD), field emission gun scanning electron microscopy (FEG‐SEM), and transmission electron microscopy (TEM). The degree of dispersion of organo‐modified clay increased with the PP‐g‐MA content. The thermal and mechanical properties were not affected by organo‐modified clay type, although the masterbatch products did have a significant influence on thermal and mechanical properties of nanocomposites. Intercalation/exfoliation was not achieved in the Nanofil SE 3000 composite. This masterbatch product has intercalants, whose initial decomposition temperature is lower than the processing temperature (T ~ 180°C), indicating that their stability decreased during the process. The Nanomax‐PP composite showed higher thermal and flexural properties than pure PP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

10.
This study describes the responsive behavior of modified amphiphilic ABA triblock copolymers of polymethyloxazoline‐block‐poly(methylhydrosiloxane‐co‐dimethylsiloxane)‐block‐polymethyloxazoline (PMOX‐b‐P(MHS‐co‐DMS)‐b‐PMOX) when subjected to compression on the water surface or to ions in the water bulk phase. The hydrophobic middle block was functionalized with spacers bearing methyl 2‐hydroxybenzoate (Bz) or 18‐crown‐6 ether (Ce) groups. The behavior at the air–water interface was studied by measuring surface pressure versus mean molecular area (π–mmA) isotherms, and atomic force microscopy (AFM) was employed to investigate the morphology of Langmuir–Blodgett (LB) films after transfer to solid supports. Ion‐responsive self‐assembly was followed using light microscopy and can be understood on a molecular level by employing 1H NMR spectroscopy. The π‐mmA isotherm of PMOX‐b‐P(MHS‐co‐DMS)‐b‐PMOX‐44Bz at the air–water interface had an extended pseudo‐plateau at a surface pressure of ca 22 mN m?1 reflecting the coil to loop transformation of the hydrophobic middle block which was absent for the crown ether‐functionalized triblock copolymer. AFM images of LB films of PMOX‐b‐P(MHS‐co‐DMS)‐b‐PMOX‐44Bz showed dewetting effects of the polymer film after transfer to a silicon wafer. LB films of PMOX‐b‐P(MHS‐co‐DMS)‐b‐PMOX‐8Ce formed surface micelles having a size of ca 50–100 nm on the solid support. The ion sensitivities of the crown ether‐derivatized copolymers in solution were investigated by exposing polymeric vesicles to potassium, sodium and magnesium ions. Exposure to K+ and Na+ led to vesicle rupture and the formation of micro‐tubular structures, while Mg2+ had no effect on the vesicular structures as confirmed using light microscopy. Specific interactions between the crown ether‐derivatized polymer and ions were further elucidated from 1H NMR experiments that indicated that K+ coordinated with the crown ether causing the dense packing to subside and leading to solubilization of the polymer in water. Copyright © 2010 Society of Chemical Industry  相似文献   

11.
Polypropylene (PP) was melt blended with nano organo‐clay masterbatch at different ratios; namely 5, 10, and 15 wt % of nano‐clay. The effect of organo‐clay content on the viscoelastic properties of the nano‐composite was studied. A miniature laboratory mixing extruder, LME, was used to blend the nano organo‐clay masterbatch with PP at 260°C and 250 rpm. The blend was pelletized first, and then a thin ribbon was extruded. Two viscoelastic tests were performed; frequency sweep at constant temperature of 80°C, and temperature sweep at constant frequency of 1.0 rad/s. As the loading of nano‐clay increased, the storage modulus, G', and the thermal resistance increased as well. Different viscoelastic models were tried and 3‐elements Maxwell model was found to describe well the viscoelastic properties of the nano‐composites. The ratio of the complex modulus to the corresponding matrix modulus at different frequencies was found to vary proportional to the nanoclay loading. This dependency was described reasonably well by modified Guth model using particle aspect ratio of 12.1. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

12.
This paper reports a simple route for the preparation of graphene/poly(styrene‐b‐butadiene‐b‐styrene) (SBS) nanocomposite films employing a vacuum filtration method. Graphene is exfoliated well by an electrochemical procedure and homogeneously dispersed in the polymer matrix. The prepared nanocomposite films were characterized by XRD, Fourier transform IR (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, AFM and SEM. Morphological studies showed that graphene formed a smooth coating over the surface of SBS. The increase in graphene concentration induces the wrinkling of graphene sheets at the composite surface which causes a further increase in surface roughness. The FTIR, Raman and XPS spectra of graphene/SBS nanocomposite films indicate the strong interactions between graphene and the polymer matrix. According to the XRD patterns, introducing SBS into graphene did not modify the graphene structure additionally, i.e. the crystal lattice parameters do not depend on SBS content in graphene/SBS nanocomposite films. The graphene/SBS nanocomposite films also exhibited better hydrophobicity due to the increased surface roughness and lower sheet resistivity (reduced 10 times) compared to exfoliated graphene. © 2018 Society of Chemical Industry  相似文献   

13.
A novel lithium solid polymer electrolyte (SPE) based on polyethylene oxide (PEO) matrix and yttrium oxide (Y2O3) as nano‐filler was prepared by solution casting technique. The Lewis acid‐based filler‐polymer coordination interactions between the surface of Y2O3 and the ether oxygen of PEO were proved by FTIR, which induced an obvious modification of crystalline morphology of the PEO‐based SPEs. Polarized optical microscope (POM) analysis shows that the induced nucleation and steric hindrance effects of Y2O3 nano‐filler result in the increased amount as well as decreased size of spherulites in the PEO matrix, respectively. Atomic force microscope (AFM) images indicate the surface morphology of PEO gets rougher as Y2O3 content increases. X‐ray diffractomer (XRD) and differential scanning calorimetry (DSC) results demonstrate the crystallinity of SPEs decreases from 51.1% to 32.5% with the Y2O3 weight ratio [m(Y2O3)/m(PEO+LiI)] increasing from 0 to 0.15. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers  相似文献   

14.
The rising interest in polymer nanocomposites leads also to an increasing concern for their photo‐oxidation resistance. The main properties and photo‐oxidation behaviour of polypropylene‐based microcomposites and nanocomposites were investigated. The results show that the use of nanosized calcium carbonate may lead to a higher photo‐oxidation rate than that of pristine polypropylene, in a way that is comparable to organo‐modified nanoclays. It is also observed that nanosized calcium carbonate causes higher photodegradation rates than microsized calcium carbonate. The main reasons for the increased photo‐oxidation rates when using organo‐modified nanoclays include the presence of iron ions, the degradation of the organo‐modifier and the formation of acidic sites on nanoclay layers, while in the case of calcium carbonate the main reasons are related to the achieved morphology and structure. The presence of calcium carbonate, especially when nanosized, significantly modifies the distribution of photo‐oxidation products in comparison to clay‐filled nanocomposites. Copyright © 2011 Society of Chemical Industry  相似文献   

15.
Bionanocomposites based on poly(3‐hydroxybutyrate) (PHB) and starch plasticized with glycerol and water [thermoplastic starch (TPS)] with organically modified montmorillonite clay as a nanofiller were obtained by melt‐blending. The influence of the clay and TPS on the thermal and mechanical properties of the resultant bionanocomposite was investigated by various techniques, such as X‐ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM), thermogravimetric analysis, differential scanning calorimetry, and nanoindentation. The results obtained by AFM showed that bionanocomposites have a surface roughness of 30.88 nm, compared to 14.53 nm for processed PHB. This result is obtained due to the migration of clay layers to the surface. From XRD and TEM it was determined that the clay layers of the bionanocomposites are completely separated. The hardness and elastic moduli of bionanocomposites have values similar to those of PHB, improving the drawbacks of the PHB–TPS blends (65:35 weight ratio). The thermal properties do not present significant changes, and only the degree of crystallinity decreased with increasing clay content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45217.  相似文献   

16.
Palladium doped ZnO was prepared by the sol‐gel and dip‐coating techniques, starting with zinc acetate and palladium chloride as precursors, followed by its hydrolysis in methanol. Acetic acid was incorporated to adjust pH, as well as acetylacetonate and monoehtylamine as stabilizers. The sol was later dipped 3 times in silica substrates. Structural, morphological, and antimicrobial properties of the films were investigated for three palladium contents (1.0, 2.5, and 5 mol %). X‐ray diffraction (XRD) showed that the films have a hexagonal structure after been annealed at 500°C. X‐ray photoelectron Spectroscope (XPS) showed that Pd is present in its oxidized form. Atomic force microscopy (AFM) from films showed a crack free and smooth surface (Ra= 18 nm), composed of cross‐linked particles. The synthesized films presented antibacterial activity against Escherichia coli and Pseudomona aeruginosa. It was observed that the higher Pd content (5 mol %) presents the higher antimicrobial ratio, 64.07%, for the E. coli, whereas for the P. aeruginosa, the lower Pd content (1 mol %), shows the higher antimicrobial ratio, 76.43%.  相似文献   

17.
Acrylic acid (AAc) and 2‐hydroxyethyl methacrylate (HEMA) mixtures were simultaneously grafted onto the surfaces of polydimethylsiloxane (PDMS) films using a two‐step oxygen plasma treatment (TSPT). The first step of this method includes: oxygen plasma pretreatment of the PDMS films, immersion in HEMA/AAc mixtures, removal from the mixtures, and drying. The second step was carried out by plasma copolymerization of preadsorbed reactive monomers on the surfaces of dried pretreated films. The effects of pretreatment and polymerization time length, monomer concentration, and ratio on peroxide formation and graft amount were studied. The films were characterized by attenuated total reflection Furrier transformer infrared (ATR‐FTIR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), zeta potential, surface tension, and water contact angle measurements. The ATR‐FTIR spectrum of the modified film after alkaline treatment showed the two new characteristic bands of PHEMA and PAAc. Both increase the polar part of surface tension (γp) after grafting and the evaluation of surface charge at pH 1.8, 7, and 12 confirmed the presence of polar groups on the surface of grafted films with a mixture of HEMA/AAc. Morphological studies using both AFM and SEM evaluation illustrated various amounts of grafted copolymer on the surface of PDMS films. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

18.
High density polyethylene/organo‐modified montmorillonite composites whit various concentrations of maleic anhydride grafted high density polyethylene (MA‐g‐HDPE) as compatibilizer (5–20 wt %) have been prepared by melt process. The extruded composite powders are applied on the treated steel surfaces using spray electrostatic powder technique, followed by oven curing at various temperatures (180°C–220°C) and times (15–45 min). The surface uniformity of produced coating films is studied by scanning electron microscopy. Comparison of micrographs of the coatings shows the composite coating films are measured using standard methods. The uniformity, adhesion, and bending strength of the coating films are compared to select high performance coatings. The results indicate that the presence of 15 wt % MA‐g‐HDPE in the coatings shows the highest properties (adhesion and bending strength) and more surface uniformity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40926.  相似文献   

19.
Well‐defined poly(dimethylsiloxane)‐block‐poly(methyl methacrylate)‐block‐poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) (PDMS‐b‐PMMA‐b‐PHFBMA) triblock copolymers were synthesized via atom transfer radical polymerization (ATRP). Surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films was investigated. The microstructure of the block copolymers was investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Surface composition was studied by X‐ray photoelectron spectroscopy (XPS). The chemical composition at the surface was determined by the surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films. The increase of the PHFBMA content could strengthen the microphase separation behavior in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films and reduce their surface tension. Comparison between the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymers and the PDMS‐b‐PHFBMA diblock copolymers showed that the introduction of the PMMA segments promote the fluorine segregation onto the surface and decrease the fluorine content in the copolymers with low surface energy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

20.
Functional copolymer/organo‐silicate [N,N′‐dimethyldodecyl ammonium cation surface modified montmorillonite (MMT)] layered nanocomposites have been synthesized by interlamellar complex‐radical copolymerization of preintercalated maleic anhydride (MA)/ organo‐MMT complex as a ‘nano‐reactor’ with n‐butyl methacrylate (BMA) as an internal plasticization comonomer in the presence of radical initiator. Synthesized copolymers and their nanocomposites were investigated by dynamic mechanic analysis, X‐ray diffraction, SEM, and TEM methods. It was found that nanocomposite dynamic mechanical properties strongly depend on the force of interfacial MA … organo‐MMT complex formation and the amount of flexible n‐butyl ester linkages. An increase in both of these parameters leads to enhanced intercalation and exfoliation in situ processes of copolymer chains and the formation of hybrid nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

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