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1.
Smart color-changing fibers attract much attention owing to their importance as a component of flexible electronics. A facile and scalable method of multicolor reversible electro–thermochromic Ag nanoparticles/reduced graphene oxide/polyurethane conductive fiber (ETC AgNPs/rGO/PU conductive fiber) is fabricated, which contains the polyurethane (PU) as the inner layer, reduced graphene oxide (rGO) with Ag nanoparticles (AgNPs) as the conductive layer, and thermochromic paste as the outermost layer. It possesses excellent electrothermal and color-changing properties and rapidly generates Joule heat at 0.5 V, which makes the fiber surface temperature reach 39.81 °C rapidly. The color switching rate is fast and changes from green to yellow within 2 s. During the process of 250 times on/off voltage, ETC AgNPs/rGO/PU conductive fibers still maintain excellent electrical and thermal properties and color change stability; even in the washing, strong acid, and strong alkali environment, they still have excellent durability. This human subjective adjustable electrical–thermal–color multi-level induced modulation makes it possible to be applied to smart wearable fields such as visual camouflage, personal thermal management, and active information transfer.  相似文献   

2.
Chain‐extended polyurethane (PU) elastomers were prepared using castor oil with 4,4′‐methylene bis (phenyl isocyanate) (MDI) as a crosslinker and 4,4′‐diamino diphenyl sulphone (DDS) as an aromatic diamine chain extender. A series of starch‐filled (from 5 to 25% wt/wt) diamines chain‐extended PUs have been prepared. The starch‐filled PU composites were characterized for physico‐mechanical properties viz, density, surface hardness, tensile strength, and percentage elongation at break. Thermal stability of PU/starch have been carried out by using thermogravimetric analyzer (TGA). Thermal degradation process of PU/starch were found to proceed in three steps. TGA thermograms of PU/starch shows that all systems were stable upto 235°C, and maximum weight loss occur at temperature 558°C. The microcrystalline parameters such as crystal size (〈N〉) and lattice strain (g in %) of PU/starch have been established using wide‐angle X‐ray scattering (WAXS) method. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2945–2954, 2003  相似文献   

3.
In this study, polycaprolactone(PCL)‐based polyurethane (PU) elastomer containing 45 wt % hard segment component was synthesized and characterized by fourier transform infrared spectroscopy, gel permeation chromatography, and X‐ray diffraction. As a toughening agent, the as‐synthesized PU was incorporated into biodegradable poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) [P(3,4)HB] by solution casting to prepare P(3,4)HB/PU composites. The microstructure and properties of P(3,4)HB/PU composites were investigated using transmission electron microscopy, X‐ray diffraction, tensile testing, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and activated sludge degradation testing. The results show that PU can disperse well in a P(3,4)HB matrix. The elongation at break of P(3,4)HB/PU composites is remarkably increased while the yield strength and elastic modulus are decreased with an increase in PU content. At the same time, it is found that the fracture characteristic of P(3,4)HB is obviously transformed from brittleness into ductility with a gradual increase in PU loading. Moreover, the thermal stability of P(3,4)HB/PU composites is significantly improved compared with that of pure P(3,4)HB. In addition, the biodegradation rate of P(3,4)HB/PU composites is evidently reduced with the increase of PU content in the activated sludge degradation testing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42740.  相似文献   

4.
Inspired by mussel adhesive proteins, catechol functional groups play an important role in the ability of the mussel to adhere to organic and inorganic surfaces. A novel functional polyurethane (PU) based on hydrolysable tannins that contain a number of catechol groups was successfully synthesized and characterized. These catechol groups were used as a reducer for Ag (I) to form Ag (0), and to prepare polyurethane/silver nanoparticles composites. These kinds of polyurethane containing Ag nanoparticles showed obvious inhibition of bacterial growth because of the conjunct actions of the well‐known antibacterial property of silver and the antifouling property of PEG. It is possible for these materials to be applied widely into antibacterial adhesive coatings for surface modification due to their low cost and the material‐independent adhesive property of catechol groups in tannins. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41349.  相似文献   

5.
A silver–polycarbonate (Ag–PC) matrix was prepared by a γ‐radiation‐assisted diffusion method, and its antibacterial properties were studied. Rutherford backscattering spectroscopy, X‐ray diffraction, and transmission electron microscopy results showed the diffusion of good, crystalline‐structured (face‐centered cubic) silver nanoparticles (AgNPs) inside polycarbonate (PC) after irradiation. Ultraviolet–visible spectroscopic results indicated a blueshift in the surface plasmon resonance of the AgNPs; this revealed a particle size decrease with increasing γ‐radiation dose. This was also supported by the scanning electron microscopy results. The microstructure of the pristine PC and silver‐doped PC was monitored with positron annihilation spectroscopy, and it showed decreases in the free‐volume hole size and fractional free‐volume for Ag–PC and γ‐ray‐irradiated PC. This corroborated the Doppler broadening spectroscopy results. The thermal degradation temperature of PC was increased because of the diffusion of AgNPs in PC. The antibacterial activity of the synthesized Ag–PC matrix was evaluated by the zone of inhibition, and the results demonstrated its bacterial growth inhibition ability. The results indicate the potential to produce an Ag–PC matrix for various applications in medical and food industries. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43729.  相似文献   

6.
The properties of inorganic nanoparticles/polymer composites depend on the dispersivity of nanoparticles in a polymer matrix. The effect of surface modification on the dispersivity of ZnO nanoparticles in a polyurethane (PU) resin matrix was investigated. The nanocomposites were characterized by scanning electron microscopy (SEM), thermogravimetric analysis, and X‐ray diffraction. The scanning electron micrographs show that ZnO nanoparticles (CDI–SA–APS–ZnO), which were modified by aminopropyltriethoxysilane (APS) and activated stearic acid (SA) by N,N′‐carbonyldiimidazole (CDI), can be homogeneously dispersed and had been encapsulated in the PU phase. The interfacial compatibility between ZnO nanoparticles and PU matrix was significantly improved by hydrophobically modifying ZnO nanoparticles with APS and SA. The tensile strength and elongation at break of PU/CDI–SA–APS–ZnO nanocomposites increased by 82 and 64% respectively, compared with the pure PU material. The thermal stability and ultraviolet‐shielding properties were also improved by incorporating ZnO nanoparticles into the PU matrix. POLYM. COMPOS., 35:237–244, 2014. © 2013 Society of Plastics Engineers  相似文献   

7.
The adhesion and interfacial properties of polyurethane (PU) foams with thermoplastic (TP) materials were investigated using different techniques. The adhesion performance of PU foam with TP materials was evaluated using the peel test method, and the adhesion durability was checked after different climate treatments. X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurements were used to study the surface and interface morphology of PU foam and TP material system. Three types of PU foam samples which differ in their composition and also five commercially available TP blends systems, based on poly(carbonate), poly(styrene‐co‐maleic anhydride), poly(acrylonitrile‐butadiene‐styrene), and silicone acrylate rubber have been used. The slow reacting foam shows the best adhesion properties with all the TP materials. The climate treatments strongly effected the PU foam adhesion durability with poly(carbonate) containing TP materials (70–80% loss in adhesion), but nearly no effect with poly(styrene‐co‐maleic anhydride). The samples with lowered adhesion could be separated by peeling without visible foam residues on the TP surface. AFM, XPS, and surface tension studies have shown that the surface properties of the TP material are still governed by the PU foam. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 479–488, 2007  相似文献   

8.
Aqueous emulsions of anionic polyurethane ionomers, based on polypropylene glycol as soft segment, isophorone diisocyanate as diisocyanate, dimethylolpropionic acid as chain extender and potential ionic center, and triethylamine as neutralizer, were synthesized. They were mixed with styrene monomers to prepare polystyrene–polyurethane (PS/PU) nanocomposites by an evocator. The sizes and distributions of the particles were measured by dynamic light scattering, and the microstructure of the nanocomposites was observed by transmission electron microscope. X‐ray photoelectron spectroscopy (XPS) was used to study the surface characterization of anionic PU and PS/PU nanocomposites. It could be found that the nanoparticles of PU could encapsulate the styrene monomers effectively and the leakage type of every element in PU was not affected by the introduction of Ps. There were more hard segments on the surface of crosslinking PS/PU nanocomposites because of the formation of crosslinking structure and interpenetrating polymer network between PU and PS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3889–3894, 2006  相似文献   

9.
Novel bioactive and optically active poly(N‐acryloyl‐L ‐phenylalanine) (PAPA) was synthesized by atom transfer radical polymerization. PAPA‐silver (Ag) nanocomposites have been successfully prepared via in situ reducing Ag+ ions anchored in the polymer chain using hydrazine hydrate as reducing agent in an aqueous medium. By controlling of the amount of Ag+ ions introduced, we have produced an organic/inorganic nanocomposite containing Ag nanoparticles with well controlled size. Nanocomposites were characterized by X‐ray diffraction (XRD), UV–Vis spectrophotometry, transmission electron microscopy, and Fourier transform infrared. XRD pattern showed presence of Ag nanoparticles. The PAPA/Ag nanocomposites with 1 : 10 silver nitrate (AgNO3) : PAPA ratio revealed the presence of well‐dispersed Ag nanoparticles in the polymer matrix. All of these Ag nanoparticles formed are spherical and more than 80% of them are in the range of 15–25 nm. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

10.
The development of new materials for microorganism immobilization is very important in wastewater treatment. In this work polyurethane (PU) foams were modified polymerizing pyrrole and aniline onto their surface by chemical oxidization to obtain polyurethane/polypyrrole (PU/PPy), polyurethane/polyaniline (PU/PANI), and PU/(PPy‐co‐PANI) supports which were used to immobilize microorganisms for municipal wastewater treatment in batch mode and continuous flow using two sequential (anaerobic/aerobic) packed bed reactors (PBR) varying the total hydraulic retention time (HRT). The supports were characterized by Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) and tested in chemical oxygen demand (COD) removal during treatment of a municipal wastewater. It was observed from SEM analysis that globular nanostructures of PPy and PPy‐co‐PANI were formed onto the PU surface with average diameters between 100 and 300 nm, which are typical of aqueous polymerization of pyrrole monomer; however irregular nanostructures were observed when PANI was homopolymerized onto the PU foam. Batch wastewater treatment after 14 days showed COD removal efficiencies of 77%, 69%, 78%, and 80% for PU foam, PU/PPy, PU/PANI, and PU/(PPy‐co‐PANI), respectively; which was explained as a function of polymers morphology deposited onto the PU foam surface. Also it was observed from the sequential PBR that for 24 h and 36 h of HRT, 80 and 90% of COD removal can be achieved; respectively.© 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42242.  相似文献   

11.
In this study, amphiphilic poly(ε‐caprolactone)–pluronic–poly(ε‐caprolactone) (PCL–pluronic–PCL, PCFC) copolymers were synthesized by ring‐opening copolymerization and then reacted with isophorone diisocyanate to form polyurethane (PU) copolymers. The molecular weight of the PU copolymers was measured by gel permeation chromatography, and the chemical structure was analyzed by 1H‐nuclear magnetic resonance and Fourier transform infrared spectra. Then, the PU copolymers were processed into fibrous scaffolds by the electrospinning technology. The morphology, surface wettability, mechanical strength, and cytotoxicity of the obtained PU fibrous mats were investigated by scanning electron microscopy, water contact angle analysis, tensile test, and MTT analysis. The results show that the molecular weights of PCFC and PU copolymers significantly affected the physicochemical properties of electrospun PU nanofibers. Moreover, their good in vitro biocompatibility showed that the as‐prepared PU nanofibers have great potential for applications in tissue engineering. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43643.  相似文献   

12.
Ag and Cu nanoparticles were immobilized into crosslinked polyurethane (PU) membranes by taking advantage of the swelling characteristics of the membranes. The formation, shape and size of the nanoparticles inside the post‐swollen PU membranes were observed by transmission electron microscopy and atomic force microscopy. X‐ray diffraction indicated the presence of the pure Ag and Cu embedded in the amorphous PU matrix. Because of their compatibility, the nanoparticles improved the thermal stability and increased the glass transition temperature of PU. The membranes exhibited interesting conducting behavior with increasing temperature. The metal immobilization increased the ionic conductivity which further increased with temperature, with an activation energy of 0.15 eV indicating a thermally activated conduction mechanism. The optical and electrical properties of these starch‐based membranes can be utilized in the development of novel sensors for biomedical applications. Copyright © 2012 Society of Chemical Industry  相似文献   

13.
A composite foam, polyurethane–melamine formaldehyde (PU/MF) foam, was prepared through foaming PU resins in the three‐dimensional netlike skeleton of MF foam. The chemical structure, morphology, cell size and distribution, flame retardancy, thermal properties and mechanical properties of such composite foam were systematically investigated. It was found that the PU/MF foam possessed better fire retardancy than pristine PU foam and achieved self‐extinguishment. Moreover, no melt dripping occurred due to the contribution of the carbonized MF skeleton network. In order to further improve the flame retardancy of the composite foam, a small amount of a phosphorus flame retardant (ammonium polyphosphate) and a char‐forming agent (pentaerythritol) were incorporated into the foam, together with the nitrogen‐rich MF, thus constituting an intumescent flame‐retardant (IFR) system. Owing to the IFR system, the flame‐retardant PU/MF foam can generate a large bulk of expanded char acting as an efficient shielding layer to hold back the diffusion of heat and oxygen. As a result, the flame‐retardant PU/MF foam achieved a higher limiting oxygen index of 31.2% and exhibited immediate self‐extinguishment. It exhibited significantly reduced peak heat release rate and total heat release, as well as higher char residual ratio compared to PU foam. Furthermore, the composite foam also showed obviously improved mechanical performance in comparison with PU foam. Overall, the present investigation provided a new approach for fabricating a polymer composite foam with satisfactory flame retardancy and good comprehensive properties. © 2018 Society of Chemical Industry  相似文献   

14.
In this study, polyurethane (PU) was synthesized using 4,4,-diphenylmethane diisocyanate (MDI) as a hard segment, polycaprolactone diol (PCL) as the soft segments and 1,4-butandiol (1,4-BD) as a chain extender. Nanosilver/graphene (Ag/G) was added to the PU matrix to prepare Ag/G/PU nanocomposites. EDS, SEM and XRD are used for assaying the silver content and characterization of Ag/G. TEM, FT-IR, XRD and EDS were used to characterize the structure and morphology of the Ag/G/PUs nanocomposites. The TEM results show that Ag/G belongs to sheet structures and is dispersed in a PU matrix. The SEM showed that the strong interfacial adhesion between the Ag/G and PU is indicated. FT-IR spectra analysis shows that the functional group of PU is free of obvious changes by adding a small amount of Ag/G in the PU matrix. XRD results showed that the main crystalline peak (26°) of Ag/G became more apparent with increasing content of Ag/G, and EDS showed that the content of Ag increased with increasing content of Ag/G in the Ag/G/PUs nanocomposites. The thermal stability and mechanical properties of Ag/G/PUs nanocomposites are improved with increasing content of Ag/G. Contact angle and AFM results showed that the hydrophobicity and surface roughness increased with increasing content of Ag/G. Moreover, the Ag/G/PUs nanocomposites exhibit antibacterial activities toward Staphylococcus aureus as well as Escherichia coli and their antibacterial rates increase with increasing Ag/G. In addition, the electrical conductivity measurements showed that both surface and volume resistance of the Ag/G/PUs nanocomposites decreased as the amount of Ag/G increased.  相似文献   

15.
A functional surface‐modification agent was synthesized via a reaction between hexachlorocyclotriphosphazene and γ‐aminopropyl triethoxysilane. Ammonium polyphosphate (APP) was modified with this agent and then incorporated into a rigid polyurethane foam (RPUF). Fourier transform infrared spectroscopy, 1H‐NMR, and X‐ray photoelectron spectroscopy were used to characterize the modified ammonium polyphosphate (M‐APP). The results show that the dispersibility was improved and the particle size decreased after the modification. The limiting oxygen index and cone calorimetry test results show that M‐APP enhanced the flame‐retardant properties of RPUF. The peak heat‐release rate of polyurethane (PU)/20% M‐APP decreased by 51.18% compared with that of PU–APP. The scanning electron microscopy results illustrate that M‐APP facilitated the formation of intumescent and compact char. The excellent flame‐retardant performance of M‐APP resulted from the flame‐inhibition and barrier effects, which were attributed to the phosphazene group and the intumescent char, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45369.  相似文献   

16.
In order to improve the toughness of polypropylene (PP) and expand its applications, a layer of polyurethane (PU) elastomer was coated on the surface of ultrafine talcum powder by an in‐situ synthesis method. In this way, an organic‐inorganic composite particle was formed. Then the surface‐treated talcum powder was mixed with melted PP to prepare PP composite materials through extrusion, granulation, and injection molding. Infrared spectral characterization and energy‐dispersive X‐ray analysis showed that there was a layer of PU elastomer on the surface of the talcum powder. Impact fracture analysis indicated that there was good compatibility between the talcum powder and the PP matrix. With the incorporation of PU elastomer coated on the surface of talcum powder, the toughness of PP was significantly improved, while the tensile strength decreased slightly. The optimum properties of the composite material were obtained when the weight fraction of talcum powder was 20% and the PU coating coverage was 25%. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers  相似文献   

17.
Functionalized graphene nanoplatelets (f‐GNS) were modified with (3‐mercaptopropyl)trimethoxysilane (MPTMS) to enhance their compatibility with the polyurethane coating matrix. The results of Fourier transform infrared spectroscopy, AFM, Raman and XRD showed that the MPTMS was successfully attached onto the surface of the graphene nanoplatelets. Functionalized graphene/waterborne polyurethane acrylate (f‐GNS/WPUA) nanocomposites were fabricated by UV‐curing technology. The SEM and TEM images indicated that f‐GNS could be well dispersed in the polymer matrix and improved the interfacial adhesion. With the incorporation of 1 wt% f‐GNS, the thermal decomposition temperature of the composites was increased by 25 °C. Meanwhile, the conductivity, hydrophobicity and tensile strength were increased. When the load was further increased, the performance of the composites showed varying degrees of reduction. However, the dielectric loss tangent (tan δ) could be maintained at 0.08 or less and the electromagnetic shielding factor of the composites reached from 5 to 36 dB, showing a good electromagnetic shielding effect at a high content (2.5 wt% f‐GNS). It was considered that f‐GNS could disperse in the waterborne polyurethane well and crosslink with the polyurethane. © 2016 Society of Chemical Industry  相似文献   

18.
Simultaneous surface functionalization and reduction of graphene oxide (GO) was achieved by using dodecyl amine (DA) as surface modifying agent. The DA modified reduced GO (DA‐G) was used for subsequent preparation of DA‐G/epoxy composites by solution mixing. Fourier transform infrared spectroscopy analysis, X‐ray diffraction (XRD) and electrical conductivity measurements were conducted to establish the concurrent functionalization and reduction of GO. The effect of DA‐G on the epoxy composites at 0 to 0.75 wt% loadings was studied by investigating its static and dynamical mechanical properties. XRD study was performed to verify the dispersion of DA‐G in the epoxy polymer. Field emission scanning electron microscopy was used to investigate the fracture surface morphology of the composites and Transmission electron microscopy was employed to further confirm the dispersion of DA‐G in the matrix. It was found that the tensile strength of the composite was increased by 38.8% with the addition of 0.5 wt% of DA‐G. The good adhesion/interaction between DA‐G and epoxy resulted in the increase of storage modulus; however, glass transition temperature (Tg) value of the composites shifted to lower temperature in comparison to the neat epoxy. Thermogravimetric analysis showed small decrease in onset degradation temperature for the composites as compared to neat epoxy except for the composites containing 0.75 wt% of DA‐G. POLYM. ENG. SCI., 56:1221–1228, 2016. © 2016 Society of Plastics Engineers  相似文献   

19.
A polyurethane (PU) was developed from poly(dimethylamine‐co‐epichlorohydrin‐co‐ethylenediamine) (PDMAE) and polyethylene glycol (PEG) as soft segment and 2,4‐toluene diisocyanate (TDI) incorporating as hard segment. Later PU was blended with poly(ethylene‐co‐ethyl acrylate) (PEEA). Poly(vinyl alcohol)‐functionalized carbon black (CB‐PVA) nanoparticles was used as filler. The structure, morphology, mechanical, crystallization, and shape memory behavior (heat and voltage) were investigated methodically. Due to physical interaction of the blend components, unique self‐assembled network morphology was observed. The interpenetrating network was responsible for 83% rise in tensile modulus and 46% increase in Young's modulus of PU/PEEA/CB‐PVA 1 hybrid compared with neat PU/PEEA bend. Electrical conductivity was increased to 0.2 Scm?1 with 1 wt % CB‐PVA nanofiller. The original shape of sample was almost 94% recovered using heat induced shape memory effect while 97% recovery was observed in an electric field of 40 V. Electroactive shape memory results were found better than heat stimulation effect. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43481.  相似文献   

20.
《Ceramics International》2015,41(8):9615-9621
Dairy effluent (DE) is environmentally toxic and needs special attention. Photocatalytic degradation of DE was studied using novel polyurethane (PU)-based membranes. Typically, silver–titanium dioxide nanofibers (AgTiO2 NFs) and silver–titanium dioxide nanoparticles (AgTiO2 NPs) were individually incorporated in PU electrospun nanofibers to overcome the mandatory sophisticated separation of the nanocatalysts, which can create a secondary pollution, after the treatment process. These nanomembranes were characterized in SEM, TEM, XRD and UV studies. The polymeric electrospun nanofibers were smooth and continuous, with an average diameter of about 550 nm, and held their nanofibrous morphology even after more than 2 h of photocatalytic degradation of DE, due to the good stability of PU in the aqueous solutions, which indicates good imprisoning of the functional photocatalysts. The PU–AgTiO2 NPs and PU–AgTiO2 NFs were effective materials for degradation of DE, even after two successive cycles. PU–AgTiO2 NPs and PU–AgTiO2 NFs showed a maximum degradation of 75% and 95%, respectively after 2 h. The significant enhancement of degradation in the PU–Ag–TiO2 NPs and PU–Ag–TiO2 NFs is attributed to the photoactivity of Ag–TiO2 material under visible light irradiation.  相似文献   

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