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1.
Poly(methyl methacrylate) (PMMA)/montmorillonite (MMT) nanocomposites were prepared by a new one‐pot technique, where the hydrophilic Na‐MMT layers were decorated with hydrophobic 1‐dodecyl‐3‐methylimidazolium hexafluorophosphate (C12mimPF6) ionic liquid in situ during melt blending with PMMA and intercalation of polymer chains took place subsequently. The in situ modification and intercalation of Na‐MMT were confirmed using X‐ray diffraction and transmission electron microscopy. The combination of the compatible C12mimPF6 with PMMA and the good dispersion of MMT layers at the nanoscale rendered the resultant PMMA/MMT nanocomposites with improved optical transparency, thermal stability and mechanical properties. Copyright © 2012 Society of Chemical Industry  相似文献   

2.
A kind of novel polyether polyurethane (PU)/clay nanocomposite was synthesized using poly(tetramethylene glycol), 4,4′‐diphenylmethane diisocyanate (MDI), 1,6‐hexamethylenediamine, and modified Na+‐montmorillonite (MMT). Here, organicly modified MMT (O‐MMT) was formed by applying 1,6‐hexamethylenediamine as a swelling agent to treat the Na+‐MMT. The X‐ray analysis showed that exfoliation occurred for the higher O‐MMT content (40 wt %) in the polymer matrix. The mechanical analysis indicated that, when the O‐MMT was used as a chain extender to replace a part of the 1,2‐diaminopropane to form PU/clay nanocomposites, the strength and strain at break of the polymer was enhanced when increasing the content of O‐MMT in the matrix. When the O‐MMT content reached about 5%, the tensile strength and elongation at break were over 2 times that of the pure PU. The thermal stability and the glass transition of the O‐MMT/PU nanocomposites also increased with increasing O‐MMT content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 6–13, 2006  相似文献   

3.
Jinbo Li 《Polymer Bulletin》2006,56(4-5):377-384
Summary Epoxy resin/polyurethane interpenetrating polymer network nanocomposites with various contents of organophilic montmorillonite (oM-EP/PU nanocomposites) were prepared by a sequential polymeric technique and an in situ intercalation method. X-ray diffraction(XRD), and transmission electronic microscopy(TEM) analysis showed that organophilic montmorillonite (oMMT) disperses uniformly in epoxy resin/polyurethane interpenetrating networks(IPNs), and the intercalated or exfoliated microstructures of oMMT are formed. Differential scanning calorimetry(DSC) test proved that oMMT promotes the compatibility of EP phase and PU phase, and glass transition temperature(Tg) of oM-EP/PU nanocomposites improves with increasing oMMT content. Mechanical properties tests and thermal gravity analysis (TGA) indicated that oMMT and the IPNs of EP and PU exhibit synergistic effect on improving mechanical and thermal properties of pure EP. The mechanism of toughing and reinforcing of oM-EP/PU nanocomposites was further discussed by scanning electronic microscope(SEM).  相似文献   

4.
BACKGROUND: In situ formation of polyethylene/clay nanocomposites is one of the prevalent preparation methods that include also solution blending and melt blending with regard to process simplification, economy in cost, environment protection and marked improvement in the mechanical properties of the polymeric matrix. In the work reported here, the preparation of linear low‐density polyethylene (LLDPE) and fabrication of polymer/clay nanocomposites were combined into a facile route by immobilizing pre‐catalysts for ethylene oligomerization on montmorillonite (MMT). RESULTS: [(2‐ArN?C(Me))2C5H3N]FeCl2 (Ar = 2,4‐Me2(C6H3)) was supported on MMT treated using three different methods. The MMT‐supported iron complex together with metallocene compound rac‐Et(Ind)2ZrCl2 catalyzed ethylene to LLDPE/MMT nanocomposites upon activation with methylaluminoxane. The oligomer that was formed between layers of MMT promoted further exfoliation of MMT layers. The LLDPE/MMT nanocomposites were highly stable upon heating. Detailed scanning electron microscopy analysis revealed that the marked improvement in impact strength of the LLDPE/MMT nanocomposites originated from the dispersed MMT layers which underwent cavitation upon impact and caused plastic deformation to absorb most of the impact energy. In general, the mechanical properties of the LLDPE/MMT nanocomposites were improved as a result of the uniform dispersion of MMT layers in the LLDPE matrix. CONCLUSION: The use of the MMT‐supported iron‐based diimine complex together with metallocene led to ethylene copolymerization between layers of MMT to form LLDPE/MMT nanocomposites. The introduction of exfoliated MMT layers greatly improved the thermal stability and mechanical properties of LLDPE. Copyright © 2009 Society of Chemical Industry  相似文献   

5.
Nanocomposite polyurethane (PU)–organoclay materials have been synthesized via in‐situ polymerization. The organoclay is first prepared by intercalation of tyramine into montmorillonite (MMT)‐clay through ion exchange process. The syntheses of polyurethane–organoclay hybrid films containing different ratios of clay were carried out by swelling the organoclay into diol and diamine followed by addition of diisocyanate and then cured. The nanocomposites with dispersed and exfoliated structure of MMT were obtained as evidenced by X‐ray diffraction and scanning electron microscope. X‐ray diffraction showed that there is no peak corresponding to d001 spacing in organoclay with the ratios up to 20 wt%. SEM images confirmed the dispersion of nanometer silicate layers in the polyurethane matrix. Also, it was found that the presence of organoclay leads to improvement in the mechanical properties. The tensile strength was increased with increasing the organoclay contents to 20 wt% by 221% in comparision to the PU with 0% organoclay. POLYM. COMPOS. 28:108–115, 2007. © 2007 Society of Plastics Engineers  相似文献   

6.
The thermal stabilities, mechanical properties, and morphologies of nanocomposites of poly(ethylene terephthalate) (PET) with two different organoclays are compared. Dodecyltriphenylphosphonium‐montmorillonite (C12PPh‐MMT) and dodecyltriphenylphosphonium‐mica (C12PPh‐Mica) were used as reinforcing fillers in the fabrication of PET hybrid fibers. The variations of their properties with organoclay content in the polymer matrix and draw ratio (DR) are discussed. Transmission electron microscopy micrographs show that some of the clay layers are dispersed homogeneously within the polymer matrix on the nanoscale, although some clay particles are agglomerated. It was also found that the addition of only a small amount of organoclay is enough to improve the thermal stabilities and mechanical properties of the PET hybrid fibers. Even polymers with low organoclay contents (1–5 wt%) were found to exhibit much higher strength and modulus values than pure PET. In the case of C12PPh‐MMT/PET, the values of the tensile mechanical properties of the hybrid fibers were found to decrease linearly with increases in DR from 1 to 16. However, the tensile mechanical properties of the C12PPh‐Mica hybrid fibers were found to be independent of DR. Copyright © 2006 Society of Chemical Industry  相似文献   

7.
The effects of soft‐segment molecular weight and organic modification of montmorillonite (MMT) on thermal and mechanical properties of segmented polyurethane (PU) elastomers were investigated. The PU/MMT nanocomposites were prepared by in situ polymerization, and the compositions included soft segments with number average molecular weights of 1000, 2000, and 2900, and organic‐modified MMT (including MMT‐30B and MMT‐I30E). The nanocomposites produced were characterized using wide‐angle X‐ray diffraction (WAXD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and mechanical testing. The TEM and XRD results revealed that both MMT‐30B and MMT‐I30E were intercalated, and partially exfoliated by the PU. Mechanical tests showed that the PU1000 series in soft‐segment molecular weight yielded superior tensile properties compared with the PU2000 and PU2900 series. Also, for a given molecular weight of soft segment in PU, the MMT‐30B nanocomposites exhibited greater increases in Young's modulus, tensile strength, and elongation at break than the MMT‐I30E counterpart, and the crystallinity of PU was enhanced by the clays. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

8.
organoclay‐modified polyurethane/epoxy interpenetrating network nanocomposites (oM‐PU/EP nanocomposites) were prepared by adding organophilic montmorillonite (oMMT) to interpenetrating polymer networks (IPNs) of polyurethane and epoxy resin (PU/EP) which had been prepared by a sequential polymerization technique. Wide‐angle X‐ray diffraction (WAXD) and transmission electronic microscopy (TEM) analysis showed that the interpenetrating process of PU and EP improved the exfoliation and dispersion degree of oMMT. The effects of the NCO/OH ratio (isocyanate index), the weight ratio of PU/EP and oMMT content on the phase structure and the mechanical properties of the oM‐PU/EP nanocomposites were studied by tensile testing and scanning electronic microscopy (SEM). Water absorption tests showed that the PU/EP interpenetrating networks and oMMT had synergistic effects on improvement in the water resistance of the oM‐PU/EP nanocomposites. Differential scanning calorimetry (DSC) analysis showed that PU was compatible with EP and that the glass transition temperature (Tg) of the oM‐PU/EP nanocomposites increased with the oMMT content up to 3 wt%, and then decreased with further increasing oMMT content. The thermal stability of these nanocomposites with various oMMT contents was studied by thermogravimetric analysis (TGA), and the mechanism of thermal stability improvement was discussed according to the experimental results. Copyright © 2005 Society of Chemical Industry  相似文献   

9.
Poly(butyl acrylate‐co‐methyl methacrylate)‐montmorillonite (MMT) waterborne nanocomposites were successfully synthesized by semibatch emulsion polymerization. The syntheses of the nanocomposites were performed in presence of sodium montmorillonite (Na‐MMT) and organically modified montmorillonite (O‐MMT). O‐MMT was used directly after the modification of Na‐MMT with dimethyl dioctadecyl ammonium chloride. Both Na‐MMT and O‐MMT were sonified to obtain nanocomposites with 47 wt % solids and 3 wt % Na‐MMT or O‐MMT content. Average particle sizes of Na‐MMT nanocomposites were measured as 110–150 nm while O‐MMT nanocomposites were measured as 200–350 nm. Both Na‐MMT and O‐MMT increased thermal, mechanical, and barrier properties (water vapor and oxygen permeability) of the pristine copolymer explicitly. X‐ray diffraction and transmission electron microscope studies show that exfoliated morphology was obtained. The gloss values of O‐MMT nanocomposites were found to be higher than that of the pristine copolymer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42373.  相似文献   

10.
Nanocomposites of polyurethane‐montmorillonite (PU‐MMT) were successfully prepared by in situ emulsion polymerization. The PU‐MMT particles size in emulsion was controlled in nanolevel, which was confirmed by laser scattering size distribution analyzer. The morphology of MMT in PU‐MMT composites was observed by transmission electron microscopy (TEM). Wide angle x‐ray diffraction (WAXD) was also used to detect the dispersion of MMT in composites. The thermal property was evaluated by dynamic mechanical analysis. Mechanical and fracture properties were also been tested. Gas barrier property was discussed on the basis of testing oxygen permeability of PU‐MMT films. The permeability coefficient of the films is found to reduce after composing with MMT, which indicates that the potential application of PU‐MMT could be realized as coating materials to prevent metal rusting. It is also found that dimethyl distearylbenzyl ammonium chloride (DMDSBA) is a better modifier for MMT in PU than dimethyldistearyl ammonium chloride (DMDSA). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

11.
The morphology and mechanical and viscoelastic properties of rubbery epoxy/organoclay montmorillonite (MMT) nanocomposites were investigated with wide‐angle X‐ray scattering (WAXS), transmission electron microscopy (TEM), tensile testing, and dynamic mechanical thermal analysis. An ultrasonicator was used to apply external shearing forces to disperse the silicate clay layers in the epoxy matrix. The first step of the nanocomposite preparation consisted of swelling MMT in a curing agent, that is, an aliphatic diamine based on a polyoxypropylene backbone with a low viscosity for better diffusion into the intragalleries. Then, the epoxy prepolymer was added to the mixture. Better dispersion and intercalation of the nanoclay in the matrix were expected. The organic modification of MMT with octadecylammonium ions led to an increase in the initial d‐spacing (the [d001] peak) from 14.4 to 28.5 Å, as determined by WAXS; this indicated the occurrence of an intercalation. The addition of 5 phr MMTC18 (MMT after the modification) to the epoxy matrix resulted in a finer dispersion, as evidenced by the disappearance of the diffraction peak in the WAXS pattern and TEM images. The mechanical and viscoelastic properties were improved for both MMT and MMTC18 nanocomposites, but they were more pronounced for the modified ones. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 103: 3547–3552, 2007  相似文献   

12.
In this study, montmorillonite (MMT)/poly(?‐caprolactone)‐based polyurethane cationomer (MMT/PCL‐PUC) nanocomposites were prepared and their mechanical properties, thermal stability, and biodegradability were investigated. PCL‐PUC has 3 mol % of quaternary ammonium groups in the main chain. The MMT was successfully exfoliated and well dispersed in the PCL‐PUC matrix for up to 7 wt % of MMT. The 3 mol % of quaternary ammonium groups facilitated exfoliation of MMT. The 1 wt % MMT/PCL‐PUC nanocomposites showed enhanced tensile properties relative to the pure PCL‐PU. As the MMT content increased in the MMT/PCL‐PUC nanocomposites, the degree of microphase separation of PCL‐PUC decreased because of the strong interactions between the PCL‐PUC chains and the exfoliated MMT layers. This resulted in an increase in the Young's modulus and a decrease in the elongation at break and maximum stress of the MMT/PCL‐PUC nanocomposites. Biodegradability of the MMT/PCL‐PUC nanocomposites was dramatically increased with increasing content of MMT, likely because of the less phase‐separated morphology of MMT/PCL‐PUC. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

13.
Epoxy‐based nanocomposites with 2, 5, and 7 wt% of montmorillonite (MMT) nanoclay were prepared using high shear melt mixing technique. The microstructural features of the nanocomposites were investigated by transmission electron microscopy (TEM). The thermal and mechanical properties were measured using differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), and dynamic mechanical analyzer (DMA). Further, the effect of voltage, temperature, seawater aging on the electrical conductivity (σDC) of the nanocomposites was also measured. To understand the free volume behavior upon filler loading, and to observe the connectivity between microstructure and other properties, positron annihilation lifetime spectroscopy was used. The TEM results revealed that MMT nanoparticles were uniformly dispersed in the epoxy matrix. Experimental results showed that the inclusion of 2 wt% MMT nanofiller increased the Tg, electrical conductivity, thermal stability, modulus, free volume of the epoxy nanocomposite significantly. This is well explained from the results of Tg (DSC and DMA), thermal stability, TGA residue, free volume analysis, and electrical conductivity. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers  相似文献   

14.
The polyethylene–clay nanocomposites were prepared by the in situ graft copolymerization of styrene containing twin‐benzyldimethyldioctadecylammonium bromine modified montmorillonite (TBDO‐MMT) in polyethylene with dicumyl peroxide (DCP) as an initiator in molten state. XRD and TEM analysis indicated that intercalated polyethylene/MMT nanocomposites are obtained. The mechanics performance, crystal behavior, thermal properties, and the effect of MMT contents on PE/MMT nanocomposite were also studied. As comparison, polyethylene/montmorillonite composites prepared by a simply melt compounding without styrene were studied as well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4921–4927, 2006  相似文献   

15.
Poly(trimethylene terephthalate) (PTT) nano composites were synthesized by in situ polymerization at high temperature with two thermally stable organoclays: 1,2‐dimethylhexadecylimidazolium‐montmorillonite (IMD‐MMT) and dodecyltriphenyl phosphonium‐MMT (C12PPh‐MMT). PTT hybrid fibers with various organoclay contents were melt‐spun at various draw ratios (DRs) to produce monofilaments. The thermomechanical properties and morphologies of the PTT hybrid fibers were characterized using differential scanning calorimetry, thermogravimetric analysis, wide‐angle X‐ray diffraction, electron microscopy, and mechanical tensile properties analysis. The nanostructure of the hybrid fibers was observed by both scanning and transmission electron microscopy, which showed that the clay layers were well dispersed into the matrix polymer, although some clusters or agglomerated particles were also detected. Unlike the hybrids containing IMD‐MMT, the clay layers of the C12PPh‐MMT hybrid fiber were more dispersed into the matrix polymer. The thermal stability and tensile properties of the hybrid fibers increased with increasing clay content for DR = 1. However, as DR increased from 1 to 9 the ultimate strength and initial modulus of the hybrid fibers with IMD‐MMT increased slightly whereas those of C12PPh‐MMT hybrid fibers decreased slightly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4535–4545, 2006  相似文献   

16.
In the present investigation, a macromonomer of polyurethane acrylate (PUA) was synthesized, and novel netlike nanocomposite materials were prepared through in situ polymerization of polyurethane acrylate macromonomers in the presence of organically modified montmorillonite (oMMT). The structure of oMMT was compared with untreated MMT by Fourier transform infrared (FTIR) and X-ray diffraction (XRD). Transmission electronic microscopy (TEM) studies showed that the silicate layers of oMMT were dispersed homogeneously in the polymer matrix. Tensile test, impact test, and thermal gravity analysis proved that the mechanical and thermal properties of the nanocomposites are superior to those of the pure system, and the mechanical properties of the cured hybrid reach maximum while the content of oMMT is 1.5 wt%. Surprisingly, dynamic mechanical thermal analysis (DMTA) displayed that the glass transition temperature (Tg) of the nanocomposites decreased with increasing the oMMT contents. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers  相似文献   

17.
In this article, the surfactants, (2‐hydroxylethyl) octadecyl dimethylammonium nitrate (OH‐C18), hexadecyltrimethylammonium bromide(C16), and mixture of trimethylchlorosilane (TM) and OH‐C18 were ion‐exchanged with cations in the montmorillonite (MMT) to generate three organic MMTs (named as OH‐C18‐MMT, C16‐MMT, and MMMT), leading to different environments of catalyst species in MMT interlayer gallery. Et[Ind]2ZrCl2 (abbreviated as EI) was supported on the above three types of OMMTs to prepare the PE/OMMT nanocomposites via in situ polymerization. By contrast, EI/MMMT showed higher activity than EI/OH‐C18‐MMT and EI/C16‐MMT under the same polymerization conditions. The other two types of catalysts, such as [(tert‐Bu)NSi(Me2)C5Me4]TiCl2 (CGCT) and Bis[N‐(3‐tert‐butylsalicylidene)anilinato] titanium (IV) dichloride (FI) were also supported on the OH‐C18‐MMT for in situ ethylene polymerization. It was found that the activity of FI/OH‐C18‐MMT for ethylene polymerization was much lower than the other two corresponding catalysts under the similar reaction conditions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

18.
In this paper, a new type of organophilic montmorillonite, co‐treated with cetyltrimethyl ammonium bromide (CTAB) and 4,4′‐diphenymethylate diisocyanate (MDI), was modified and applied to prepare polyurethane/montmorillonite nanocomposites via in situ polymerization. The nanoscale montmorillonite layers were exfoliated and dispersed relatively homogeneously in the polyurethane matrix, and characterized by X‐ray diffraction and transmission electron microscopy. The thermal degradation temperature of the nanocomposites increased, as compared with pristine polyurethane. Dynamic mechanical analysis confirmed the constraining effect of exfoliated montmorillonite layers on polyurethane chains, which benefited the increased storage modulus and increased glass transition temperature. Tensile tests showed that the exfoliated nanocomposites were reinforced and toughened by the addition of nanometer‐size montmorillonite layers. Copyright © 2006 Society of Chemical Industry  相似文献   

19.
Poly(methylmethacrylate) (PMMA)/montmorillonite (MMT) nanocomposites were prepared by in situ suspension polymerization. MMT was previously organically modified by different modification agents [dioctadecyl dimethyl ammonium chloride (DODAC) and methacrylatoethyltrimethyl ammonium chloride (MTC)] and different modification method (cation‐exchange reaction and grafting reaction), ultimately giving rise to five kinds of organomodified MMT (OMMT). The structure of the OMMT was studied by Wide angle X‐ray diffraction (WAXD) and Fourier transform infrared spectroscopy (FTIR). Meanwhile, the structure of the PMMA/MMT nanocomposites microspheres was also investigated by WAXD. The molecular weight of the polymers extracted from PMMA/MMT nanocomposites was measured by gel permeation chromatograph (GPC). Finally, the mechanical properties of these PMMA/MMT nanocomposites were studied in detail. It was found that large interlayer spacing (d001) of OMMT could not entirely ensure an exfoliated structure of resultant PMMA/MMT nanocomposites, while OMMT with relative small d001 could still yield exfoliated structure as long as the compatibility between OMMT and polymer matrix was favorable. In addition, the results of mechanical investigation indicated that the compatibility between OMMT and PMMA matrix turned out to be the dominant factor deciding the final mechanical properties of PMMA/MMT nanocomposites. POLYM. COMPOS., 37:1705–1714, 2016. © 2014 Society of Plastics Engineers  相似文献   

20.
BACKGROUND: The development of polymeric nanocomposites incorporating intercalated or exfoliated layered silicate clays into the organic matrix has been substantially motivated by the significant improvements induced by the presence of the inorganic component. Moreover, understanding and controlling the dispersion of inorganic layers into segmented polyurethane matrices by means of ionic interactions, and exploiting these interactions to enhance physicomechanical behaviour, could be of great interest in the field of polymer nanocomposites. RESULTS: New cationic polyurethane elastomers were prepared starting from poly(butylene adipate)diol (Mn = 1000 g mol?1), 4,4′‐diphenylmethane diisocyanate, 1,4‐butanediol and N‐methyldiethanolamine or N,N′‐β‐hydroxyethylpiperazine, used as potential quaternizable moieties. The characterization of the polymers was achieved using specific analyses employed for the macromolecular samples (Fourier transform infrared and 1H NMR spectroscopy, thermogravimetric analysis (TGA), gel permeation chromatography). An extension of our research on polymers reinforced with organically modified montmorillonite (OM‐MMT) in order to prepare hybrid composites with improved properties was performed and the resulting materials were characterized using TGA, X‐ray diffraction, atomic force microscopy and scanning electron microscopy. Also, the mechanical properties of the cationic polyurethane/OM‐MMT composites were investigated in comparison with the pristine ionic/non‐ionic polymers and their composites containing non‐ionic polymer blended with OM‐MMT or ionic polymer and unmodified MMT. CONCLUSION: The insertion of the organically modified clay into the polymeric matrix gave an improvement of the mechanical properties of the polyurethane composites, especially the tensile strength and stiffness of the hybrid materials. Copyright © 2009 Society of Chemical Industry  相似文献   

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