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1.
    
2,2,6,6‐Tetramethylpiperidinyloxyl (TEMPO)‐containing polymer brushes were grafted onto crosslinked polystyrene microspheres via surface‐initiated activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) of 2,2,6,6‐tetramethyl‐4‐piperidyl methacrylate, followed by an oxidation process with 3‐chloroperoxybenzoic acid as oxidant. The synthesized nitroxide polymer brushes included homopolymer brushes, block copolymer brushes, and random copolymer brushes with various TEMPO contents and molecular weights. They were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. These nitroxide brushes bearing high TEMPO contents were used as recoverable catalysts for the hypochlorite and aerobic oxidation of primary alcohols to aldehydes. The effects of polymer brush structure on the catalytic properties were studied and discussed. The results showed that these nitroxide polymer brushes had excellent catalytic properties and good recycling performances. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44365.  相似文献   

2.
    
Naturally available halloysite nanotubes (HNTs) with hollow nanotubular structures were used as reinforcement in poly(ε‐caprolactone) (PCL). The PCL/HNT nanocomposites were prepared by melt mixing the polymer with as‐received HNTs up to 10 wt % in an internal batch mixer. Transmission electron microscopy analysis indicated that the HNTs were dispersed uniformly on the nanoscale throughout the PCL matrix. Differential scanning calorimeter studies revealed that the PCL crystallinity was decreased in the nanocomposites, and the HNTs dispersed in the PCL matrix led to an increase in the non‐isothermal crystallization temperature of the PCL. Tensile and dynamic mechanical tests showed great enhancement in strength and stiffness at low HNT content, while still maintaining the ductility of the PCL. The glass transition temperature (Tg) of the pristine PCL was substantially increased with increase in filler loading, which indicates good reinforcing effect imparted by the addition of HNT. Melt rheological studies revealed that the nanocomposites exhibited strong shear thinning behavior, and a percolated network of HNT particles was formed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

3.
    
Carbon nanofiber sheets were developed through filtering well‐dispersed carbon nanofiber (CNF) through filtering well‐dispersed aqueous solution of CNF particles with 0.4 μm hydrophilic polycarbonate membrane by the aid of high‐pressure air. They were used to functionalize composites by the resin transfer molding method. Their functionalized composites were characterized with scanning electron microscopy (SEM), four‐point probes and a vector network analyzer to measure their morphologies, electrical conductivity, and electromagnetic interference (EMI) shielding performance over the frequency range of 8–12 GHz (X band), respectively. Their morphologies show that CNF particles are overlapped and tightly connected with each other in their interconnected networks. The CNF sheets are exposed on the surface, although their networks are partially penetrated by polyester resins. Their electrical conductivity can be 3.0 ± 0.2 Scm?1 or so, much higher by ten orders of magnitude than the reported electrical conductivity of CNF‐filled composites. Their EMI shielding effectiveness slightly varies in a range of ?30 dB to ?35 dB as a function of frequency, much higher than that of most CNF or carbon nanotube–filled composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41873.  相似文献   

4.
    
The segmental dynamics of functional graphene (fGR)/poly(ether sulfone ether ketone ketone) (PESEKK) nanocomposites were investigated via differential scanning calorimetry and dynamic mechanical analysis (DMA) measurements. First, fGR was prepared using graphene oxide and sodium dodecylbenzene sulfonate. Subsequently, a series of fGR/PESEKK nanocomposites were prepared through solution blend. When the sulfone groups were introduced into the segments of PESEKK polymers, the glass transition temperature (Tg) of PESEKK was higher than that of free sulfone functionalized poly(ether ketone ketone). The fGR/PESEKK nanocomposites displayed a uniform nanostructure because of the strong interfacial interaction between fGR and PESEKK. With the increase in the fGR contents, the Tg values of fGR/PESEKK nanocomposites decreased. Two loss factor peaks were noted in the fGR/PESEKK nanocomposites, which were characterized via DMA. The α′‐relaxation of the nanocomposites at low temperature was assigned to polymer chains close to the polymer/filler interface with mobility higher than that in the bulk unfilled PESEKK (α‐relaxation). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44391.  相似文献   

5.
    
Exploration of new functionalization approaches to inert rigid fiber, activation inert surface, and enhancing interface adhesion is urgently required for fiber‐based multiphase materials. In this paper, we developed a simple yet efficient method towards active functionalized poly(p‐phenylene terephthalamide) fiber through mussel‐adhesive, self‐polymerization, and successive dipping–drying procedure based on as‐designed detachable equipment. In comparison with current acid etching and high energy radiation methods, the active functional strategy achieves scatheless functional modification to inert rigid fiber. Attribute to π–π conjugation effect, the new active nanolayers integrate rigid fiber and polymer matrix into homogeneous‐like structure. Consequently, the functionalized fiber‐based composites exhibit great mechanical property and desirable field‐responsive ability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43018.  相似文献   

6.
    
Monodispersed poly(acrylonitrile) [p(AN)] particles were prepared by surfactant free emulsion polymerization and the hydrophobic nitrile groups were converted to hydrophilic amidoxime groups by treatment with hydroxylamine hydrochloride (NH2OH.HCl) in water. The p(AN) and amidoximated p(AN) [amid‐p(AN)] particles were characterized by Fourier transformation infrared (FT‐IR) spectroscopy, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). The prepared particles were used as adsorbents in the removal from aqueous media of three different types of pollutants; organic dyes methylene blue (MB), and rhodamine 6 G (R6G), a heavy metal ion Cd (II), and a herbicide paraquat (PQ). The effects of various parameters such as amidoximation, pH of solution, amount of particles, and the initial concentration of solution were investigated. Upon amidoximation, a great increase in the adsorption capacity of the prepared particles was observed as the adsorbed amounts were increased to 87, 91, 74, and 91 mg/g from 5, 1.54, 1.06, and 1.22 mg/g for Cd (II), MB, R6G, and PQ, respectively. The amid‐p(AN) particles were also able to remove considerable amounts of these pollutants from tap, river, and sea water. Langmuir, Freundlich, and Temkin adsorption isotherms were applied and it was found that the adsorption of Cd (II) and PQ followed the Langmuir adsorption model, whereas the adsorption of MB was found to obey the Freundlich adsorption isotherm. Pseudo first‐order and pseudo second‐order kinetics were also applied and the results showed that the adsorption processes of Cd (II), PQ, MB, and R6G follow pseudo second‐order kinetics. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43032.  相似文献   

7.
    
Carbon nanotubes (CNTs) and graphene were separately incorporated into the cross‐linked network of styrene–divinylbenzene composites via in situ suspension polymerization. The prepared copolymers were first chloromethylated and then aminated with trimethylamine to obtain ion exchange resins (IERs). The CNTs‐based and graphene‐based composites exhibited good dispersion throughout the polymer matrix with strong interaction within the network. Remarkable enhancement in antiswelling properties and thermal stabilities confirmed that graphene showed better compatibility and stronger interfacial adhesion than CNTs. The structural and thermal properties of the CNTs‐based and graphene‐based IERs were also significantly improved even at low loadings of 0.4 wt % compared with those when no CNTs and graphene were added. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41234.  相似文献   

8.
    
High‐performance blend of polypropylene (PP) and polycarbonate (PC) has not been explored. The difficulty is caused by the big differences in melt viscosity (PP: low viscosity vs. PC: high viscosity) and polarity (PP: nonpolar vs. PC: polar). We put forth a new approach using a reactive plasticizer which is preferentially soluble with PC and polymerizable by organic peroxide. As the plasticizer, diallyl phthalate and triallyl cyanurate (TAC) were used. By reactive extrusion of PP/PC/plasticizer/dicumyl peroxide (e.g., 80/14/6/0.12 wt. ratio), reaction‐induced phase decomposition took place in the dispersed PC particles to develop a regularly phase‐separated nanostructure and the graft copolymer of PP and polymerized plasticizer was in situ generated at the interface. The extruded blend showed an excellent ductile behavior with about 500%‐elongation at break. TAC was very effective to elevate the heat resistance. Then, a super‐ductile PP/PC blend with high heat resistance was successfully developed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

9.
    
Two different kinds of micro‐nanoconstrained damping structure units (M‐NCDSUs) were prepared by carboxyl‐terminated butadiene acrylonitrile copolymer and epoxy‐terminated butadiene acrylonitrile copolymer liquid rubbers intercalating organic montmorillonite, respectively. The prepared M‐NCDSUs were then blended with epoxy resin to obtain damping structure integration nanocomposites. The X‐ray diffraction and transmission electron microscope measurements applied for the obtained samples confirmed the good formation of M‐NCDSUs in the epoxy network. The tensile strength decreased slightly with the addition of M‐NCDSUs, whereas the damping properties measured by dynamic mechanical analysis showed a remarkable increase. Besides, the cured epoxy resin exhibited a two‐phase morphology where the spherical rubber phase dispersed uniformly in the epoxy matrix. The nanocomposites containing M‐NCDSUs showed superior comprehensive properties compared with that without the functional units. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39797.  相似文献   

10.
    
Current fuel cell technology demands improvements for widespread use, and novel polymer materials may be able to achieve the necessary enhancements. This work inspects the composition, structure, and properties of poly(ethylene glycol) (PEG)–aromatic polyimide systems aimed at polymer electrolyte membrane applications, as PEG is a known ion conductor and aromatic polyimides are quite stable. Liquid electrolytes were incorporated into the polymers through soaking to achieve ionic conductivity. By varying polyimide and liquid electrolyte, the polymers were analyzed for their structure and conductivity. Fourier transform infrared spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, small‐angle X‐ray scattering, electrochemical impedance spectroscopy, and cyclic voltammetry were used as characterization tools. Electrolyte identity impacts liquid uptake and conductivity. Polyimide identity can influence the size and variability of the doped polymer structure, which ultimately can change conductivity by up to 28%, with the maximum conductivity being 102 mS/cm at 80°C and 70% RH. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41675.  相似文献   

11.
    
In this study, polyhedral oligomeric silsesquioxane glycidylisobutyl‐POSS was dispersed in epoxy resin by ultrasound, and the parameters of a phantom model, the Williams–Landel–Ferry (WLF) and Vogel–Fulcher–Tammann (VFT) equations were modeled using dynamic mechanical analysis (DMA) to evaluate their influence on the glass transition state. The relaxation and retardation time distributions were estimated using a nonlinear regularization method, and the estimated physical parameters were discussed based on the results obtained from transmission electron microscopy (TEM). The TEM analysis indicated higher POSS dispersion with a spherical shape. The POSS dispersion was associated with the formation of micelles due to their hybrid character. The micelles favored the interconnections of the nodular microstructure of the epoxy thermosetting, which led to an increase in their Tg values. These interconnections increased the structure's percolation, promoted a reduction in the thermal expansion coefficient and resulted in a more homogeneous glass transition, in terms of a cooperative distribution in the relaxation times at the time scale measured. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41453.  相似文献   

12.
    
The epoxy‐silica hybrids showing high Tg and thermal stability are prepared by the non‐aqueous sol–gel process initiated with borontriflouride monoethylamine. Tetramethoxysilane (TMOS) is used as a precursor of silica and 3‐glycidyloxypropyl trimethoxysilane as a coupling agent to strengthen the interphase interaction with an epoxy matrix. The basic factors governing the nonaqueous sol–gel process are studied in order to reveal the formation–structure–properties relationships and to optimize the hybrid composition as well as conditions of the nonaqueous synthesis. The formation of the hybrid, its structure, thermomechanical properties and thermal stability are followed by chemorheology experiments, NMR, DMA and TGA. The most efficient reinforcement of the epoxy network is achieved by the combination of both alkoxysilanes, showing synergy effects. The hybrids with a low content (～10 wt %) of the in situ generated silica exhibit dramatic increase in Tg and the high modulus, 335 MPa, up to the temperature 300°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40899.  相似文献   

13.
    
Polyacrylamide‐based (PAM) polymers are the most widely used synthetic water‐soluble polymer so they are applied in a range of industries. However, they suffer from a number of limitations which requires the development of synthetic routes that can accurately control polymer structure and hence function. This study describes a carbodiimide mediated coupling reaction (CMC) that is used to generate modified polyacrylamide (PAM) including hydrophobically modified water‐soluble polymers (HMWSP). The reaction proceeds efficiently in water and does not require organic solvents or high temperatures. The approach is flexible due to the efficiency of the CMC reaction allowing for accurate control over polymer structure and function. This is confirmed using acid‐base titration, spectroscopy, viscometry, and rheology. The viscosity of the polymers varies over a broad range with those containing larger hydrophobic group (dodecyl) showing the highest viscosity. The hydrophobicity of the pendent group determines how it influences viscosity and using this new synthetic approach polymer with the same molecular weight can be compared. Linear hydrocarbon pendent groups are more hydrophobic than the cyclic versions resulting in higher viscosity. However, the spatial arrangement of the pendent group (linear or cyclic) also affects the viscosity at higher pendent group contents. The number of modified PAMs that can be generated is expansive because the approach works with a number of different functional groups and base polymers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42797.  相似文献   

14.
    
Polar polystyrene‐isoprene‐styrene (SIS) copolymers having epoxide groups and long polybutadiene (PB) branches were synthesized via the combination of in situ epoxidation, anionic polymerization and graft‐onto reaction. They were characterized with 1H NMR, GPC, FT‐IR, DSC, and contact angle test. Their polarity was determined by the epoxidation degree and graft efficiency. The epoxidation degree linearly increased with the epoxidation time. The graft efficiency decreased with the branch length, but increased with the epoxidation degrees. Although their glass transition temperature (Tg) of diene blocks and flexibility properties had been negatively affected by in situ epoxidation, they could be modulated by the epoxidation degree, branch length, and branch density. Their Tg could be tailored by the branch length and branch density since they fitted the Fox equation very well, especially as the longer branches were grafted. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40303.  相似文献   

15.
    
Flexible poly(dimethylsiloxane) (PDMS) or rigid bisphenol A (BPA) with diglycidyl ether end groups was linked to polyurethane (PU), which was composed of 4,4′‐methylenebis(phenyl isocyanate) as a hard segment and poly(tetramethylene ether)glycol as a soft segment. A control PDMS (CPDMS) series was prepared with an additional deprotonation step by NaH. The spectroscopic, thermal, tensile, shape memory, and low‐temperature flexibility properties were compared with those of plain PU to investigate the effects of linking the flexible PDMS or the rigid BPA on PU. The soft segment melting peaks were not affected by the PDMS content for the PDMS series but disappeared as the BPA content increased in the BPA series. The soft segment crystallization of PU was completely disrupted as the linked BPA content increased in the differential scanning calorimetry results and disappeared in the dynamic mechanical analysis results. The glass transition temperature (Tg) of the BPA series increased with increasing BPA content, whereas that of the PDMS series remained the same. The tensile strength of the PDMS series sharply increased with increasing PDMS content. The shape retention of the BPA series at ?25 °C sharply decreased as the BPA content increased. Finally, the BPA series linked with rigid aromatic BPA demonstrated excellent low‐temperature flexibilities compared with the PDMS series and plain PU. Compared with PUs linked with PDMS, PUs linked with rigid BPA demonstrated a significant change in the cross‐link density, thermal properties, shape retention, and low‐temperature flexibility. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43284.  相似文献   

16.
    
To improve the pervaporation performance of PDMS membrane, alkyl groups with different chain length were grafted into PDMS matrix. The prepared membranes were characterized by ATR‐IR, DSC, TGA, PALS, and tensile testing. The effects of alkyl grafting on pervaporation performance of PDMS membrane were investigated in separation of ethyl acetate/water mixture. Experimental results show that the separation factor of PDMS membrane is largely improved by alkyl grafting because of the enhanced preferential sorption of ethyl acetate, and this improvement depends on alkyl grafting ratio and alkyl chain length. The total flux of PDMS membrane reduces after alkyl grafting owing to the decreased free volume. When grafting ratio is above 6.9%, membrane grafted with shorter alkyl groups is preferred for pervaporation. The best pervaporation performance is achieved by 9% octyl grafted PDMS membranes with a separation factor of 592 and a total flux of 188 gm?2 h?1 in separation of 1% ethyl acetate/water mixture at 40 °C. Moreover, this octyl grafted PDMS membrane also exhibits excellent separation performance in removal of butyl acetate, methyl‐tert‐butyl ether, and n‐butanol from water. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43700.  相似文献   

17.
To create reversible supramolecular ionic networks, ionic cross‐links were formed from acid pendant functions in poly(styrene‐co‐methacrylic acid) copolymers by the addition of calcium carbonate. The random dispersion of acid functions in the polystyrene chain is ensured by NMR analysis. The partial reaction of the calcium carbonate with the carboxylic acids is highlighted by a limewater test. The influence of methacrylic acid and calcium‐carbonate contents on the formation of an ionic network has been studied through solubility tests. Two main effects were obtained: the exfoliation of the unreacted calcium carbonate characterized by TEM is due to ionic interactions at the surface of nanometric particles that form the first level of organization of the calcium carbonate. Another part of the calcium carbonate reacts with carboxylic acid and is detached from particles to form clusters as shown by x‐ray analysis. Finally, by analyzing the dynamic rheological spectrum, the conclusion that the strength of the ionic bonds arises with the calcium content is made. The interest of such an approach with a wide range of observed phenomena in the material is a one‐batch process to make thermoreversible nanocomposite networks. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

18.
    
Specimens of acidic multi‐walled carbon nanotubes (AMWNTs) reinforced polyvinyl alcohol (PVA) nanocomposites (AMWNTs‐PVA) were prepared using different amounts of AMWNTs by the traditional solution casting, involving ultrasonic wave agitation. The microstructures and tensile properties of AMWNTs‐PVA were investigated by scanning electron microscopy, dynamic mechanical analysis, and quasi‐static tensile testing. AMWNTs had good compatibility with PVA and dispersed evenly in the PVA matrix. The incorporation of AMWNTs improved the tensile modulus and strength of the PVA. The shape recovery testing revealed the shape recovery capacity of AMWNTs‐PVA. It was observed that the recovery ratio increased, and the shape recovery rate slightly decrease with the increase of AMWNTs content. The results showed that the AMWNTs had strong interaction with the segments of the PVA and hence affected the shape recovery behavior of PVA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

19.
    
Acrylonitrile–butadiene–styrene (ABS) nanocomposite filaments with different inorganic nanofillers for fused deposition modeling (FDM) were prepared by melting extrusion and printed via a commercial FDM three‐dimensional printer. The effects of the nanoparticles on the mechanical strength, anisotropy, and thermal properties of the ABS specimens were evaluated. The performances of the virgin ABS samples manufactured by FDM and injection molding were also studied. The results show that the tensile strength (TS) of the pure ABS made by FDM was just up to 70% of the value obtained from the injection‐molded specimens. The mechanical anisotropy of the pure ABS samples was very evident when the building orientation was changed. However, we found that the addition of nanofillers significantly reduced the mechanical anisotropy and improved the mechanical strength and thermostability of the ABS samples fabricated by FDM technology. The TS and flexural strength of the ABS samples increased by 25.7 and 17.1%, respectively, with the introduction of nanomontmorillonite. The addition of nano calcium carbonate lowered the mechanical anisotropy of ABS from 42.1 to 23.9%. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44470.  相似文献   

20.
    
The focus of this research is the study of the microstructures and miscibility at the interface between semi‐crystalline and amorphous PLAs [poly (l ‐lactic acid)(PLLA) with poly (l ,d ‐lactic acid)(PDLLA), respectively]. The blends are prepared through thermal processing (extrusion and hot‐pressing). To increase the area of interface between PDLLA and PLLA, the fibers from PLLA and PDLLA are used. Thermal and microstructures of the blends were studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM), dynamic thermogravimetric analysis(DMA), small‐angle X‐ray diffraction(SAXS) and wide‐angle X‐ray diffraction (WAXD). The two PLAs are miscible in molten state. However, phase separation is detected after various thermal treatments, with PDLLA being excluded from the regions of interlamellar PLLA regions when PDLLA content is low, as determined from X‐ray diffraction studies. The compatibility between the two PLAs is not perfect in the molten state, since enthalpies of the various blends at Tg are lower than any pure PLA material. The semi‐crystalline PLLA fiber can recrystallize alone in the molten amorphous PDLLA, and a higher nuclei density is observed at the interface. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41205.  相似文献   

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