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1.
Polyurethanes (PU) were synthesized from lignin by first preparing a prepolymer from esterified sugar‐based trihydroxyl compound xylaric acid and a 20 mol % excess of methylene diphenyl diisocyanate. The prepolymer was crosslinked with 5, 10, and 15 wt % of an industrial soda lignin, and polyethylene glycol was used to bring soft segments into the material structure. The total amount of bio‐based starting materials was as high as 35%. Evidence for the reaction between the prepolymer and lignin was observed using Fourier transform infrared spectroscopic analysis and 13C nuclear magnetic resonance spectroscopy. The thermal properties of the materials were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The mechanical and viscoelastic properties of the materials were determined by dynamic mechanical analysis (DMA). The glass transition temperatures (Tg) obtained from DSC and DMA showed a trend of increasing Tg with the increasing amount of lignin. A similar trend was observed with TGA for the increasing thermal stability up to 550oC with the increasing amount of lignin. The lignin‐polyurethanes obtained were stiff materials showing high Young's modulus values. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39714.  相似文献   

2.
Superabsorbent hydrogels were prepared from chitin dissolved in lithium chloride and N‐methyl‐2‐pyrrolidinone by esterification crosslinking with 1,2,3,4‐butanetetracarboxylic dianhydride (BTCA). The absorbency of the chitin hydrogel was strongly dependent on the ratio of BTCA feed to chitin. The hydrogel prepared at the feed ratio of 5 showed the highest absorbency (345 g/g‐polymer), and the hydrogel was composed of 0.65 molecules of BTCA per monomer unit of chitin. The hydrogels exhibited good biodegradability by chitinase with a maximum degradation of 91% within 7 days. This method for obtaining the chitin hydrogel was also applicable to cellulose and chitin mixtures, and 1 : 1 cellulose/chitin hybrid hydrogels could be obtained by the esterification crosslinking of a mixture with a 1 : 1 molar ratio of cellulose and chitin. The optimal BTCA feed ratio of 5 resulted in the cellulose/chitin hydrogel with the highest water absorbency (329 g/g‐polymer), and the hydrogel contained 0.65 molecules of BTCA per polysaccharide monomer unit. In addition, the hybrid hydrogels were degraded by cellulase as well as chitinase. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

3.
Solid polymer electrolyte membranes consisting of polyacrylonitrile (PAN) as a host polymer, ammonium nitrate (NH4NO3) as a complexing salt, and propylene carbonate (PC) as a plasticizer were prepared by a solution casting technique. An increase in the amorphous nature of the polymer electrolytes was confirmed by X‐ray diffraction analysis. A shift in the glass‐transition temperature of the PAN/NH4NO3/PC electrolytes was observed in the differential scanning calorimetry thermograms; this indicated interactions between the polymer and the salt. The impedance spectroscopy technique was used to study the mode of ion conduction in the plasticized polymer electrolyte. The highest ionic conductivity was found to be 7.48 × 10?3 S/cm at 303 K for 80 mol % PAN, 20 mol % NH4NO3, and 0.02 mol % PC. The activation energy of the plasticized polymer electrolyte (80 mol % PAN/20 mol % NH4NO3/0.02 mol % PC) was found to be 0.08 eV; this was considerably lower than that of the film without the plasticizers. The dielectric behavior of the electrolyte is discussed in this article. A literature survey indicated that the synthesis and characterization of ammonium‐salt‐doped, proton‐conducting polymer electrolytes based on PAN has been rare. The use of the best composition membrane (80 mol % PAN/20 mol % NH4NO3/0.02 mol % PC) proton battery was constructed and evaluated. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41743.  相似文献   

4.
Amphiphilic conetwork–structured copolymers containing different lengths of ethylene oxide (EO) chains as ionophilic units and methyl methacrylate (MMA) chains as ionophobic units were prepared by free radical copolymerization and characterized by FTIR and thermal analysis. Polymer gel electrolytes based on the copolymers complexed with liquid lithium electrolytes (dimethyl carbonate (DMC) : diethyl carbonate (DEC) : ethylene carbonate (EC) = 1 : 1 : 1 (W/W/W), LiPF6 1.0M) were characterized by differential scanning calorimetry and impedance spectroscopy. A maximum ion conductivity of 4.27 × 10?4 S/cm at 25oC was found for the polymer electrolyte based on (PEG2000‐b‐GMA)‐co‐MMA with long EO groups. Moreover, the effect of temperature on conductivity of the amphiphilic polymer electrolytes obeys the Arrhenius equation. The good room temperature conductivity of the polymer electrolytes is proposed to relate to the enhancement in the amorphous domain of the copolymers due to their amphiphilic conetwork structure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

5.
Thermal oxidative stabilization (TOS) reactions, mainly cyclization, oxygen uptake, dehydrogenation, crosslinking, and disproportionation termination of cyclization in poly(acrylonitrile‐co‐itaconic acid) (PAI), are tracked quantitatively by the combination of second‐derivative and cure‐fitting operations in the Fourier transform infrared spectroscopy spectra (FTIR) range of 1800–1000 cm?1 and 2300–2100 cm?1. Except the cyclization and disproportionation of cyclization are chemical‐reaction‐controlled process, the other three reactions are both diffusion‐controlled and chemical‐reaction‐controlled processes. The formation of free and conjugated carbonyl group need the optimal cyclization rate, adequate unreacted linear PAI chains, and appropriate oxidation ability coordinated. The higher temperature, the faster rate and the higher extent of the cyclization and the crosslinking reactions as well as the faster disproportionation termination of cyclization. The length of the formed cyclic structures became shorter as the evolution of TOS process, especially for 265 °C. The crosslinking, oxygen uptake, dehydrogenation, and termination of cyclization reactions become dominant with the proceeding of TOS process, especially as the cyclization extent above 0.8 and at high temperature such as 265 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45934.  相似文献   

6.
In this article, we report the alumina‐supported, microwave (MW)‐induced synthesis of Cassia marginata seed gum‐graft‐polyacrylamide (MWS‐GP). No initiator or catalyst was required in the synthesis, and the conditions for the grafting were optimized by variation of the acrylamide concentration, MW power, and exposure time. At an identical monomer concentration, a higher level of grafting was observed in the solid‐supported method than under aqueous conditions (the MW‐assisted or redox‐initiated thermal method). The used alumina support was easily separated from MWS‐GP and reused for another three cycles without any significant loss in its efficiency as a solid support. MWS‐GP synthesized under optimum conditions was characterized with Fourier transform infrared spectroscopy, 13C‐NMR, thermogravimetric analysis, and X‐ray diffraction, with C. marginata gum as a reference. The properties of MWS‐GP and its saponified derivative were studied to explore the applicability areas of the copolymer in hydrogel formation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

7.
In this article, a novel recyclable β‐cyclodextrins (β‐CDs)‐based supramolecular adsorbent had been fabricated. With Fe3O4 magnetic nanoparticles as core, the adsorbent could be separated from water conveniently. Moreover, the hydrophobic β‐CDs caving had strong host‐guest interaction with organic compounds to form complexes. With the pH value changing, the stable complexes would disassemble to recover the adsorbent. Fourier transform infrared analysis, X‐ray diffraction measurement, transmission electron microscopy measurements, thermogravimetric analysis, and vibrating sample magnetometer analysis had been explored to confirm the structure and properties of supramolecular adsorbent. Congo red and Rhodamine B were used to characterize the adsorption capacity of adsorbent. By changing the parameters such as temperature, time, adsorbent dosage, and pH value indicated that the designed adsorbent could rapidly remove organic dyes from water with satisfactory removal effects and adsorbent recycling capacity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45084.  相似文献   

8.
One strategy to create chemical and physical cross‐links simultaneously is to introduce into the chemical network hydrogen bonding with clay nanofillers. Understanding the relaxation mechanisms of these systems is crucially important and has drawn the extensive interest of many scientists. In this work, the influence of different amounts of montmorillonite on the structural and rheological properties of guar gum hydrogels was investigated. Depending on the clay content, different nanostructures were identified by X‐ray diffraction (XRD) and their effect on the rheological properties of the dual hydrogels was studied. From stress and frequency sweep tests it emerged that all the samples exhibit a weak gel behavior and showed a maximum for G″ that can be ascribed to the breaking and reforming of transient physical crosslinks. This relaxation mode is more pronounced for the hydrogel for which a minimum in the swelling degree was observed. On the basis of these results, a model structure was proposed according to which the clay sheets act as effective multifunctional cross‐linkers. The more homogeneously dispersed are the clay platelets, the higher is the density of physical crosslinks. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41373.  相似文献   

9.
Polystyrene (PSt) or poly(vinylbenzyl chloride) (PVBC) crosslinked with divinylbenzyl (DVB) materials were synthesized through free radical polymerization into templates formed by the surfactant polyoxyethylene (4) lauryl ether (Brij‐30). The chemical composition of the final products was verified through attenuated total reflectance infrared spectroscopy (ATR‐IR) and the thermal behavior was investigated through thermogravimetric analysis (TGA). Depending on the organization of Brij‐30 in aqueous solution, three characteristic structures, namely spherical nanoparticles, platelet‐like objects and three‐dimensional networks, were identified through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The spherical nanoparticles and the platelet‐like objects form rather stable dispersions, especially in aqueous surfactant solutions, as exemplified by the evolution of the turbidity of the PSt‐based materials, using sodium dodecyl sulfate as surfactant. All materials retain their integrity even after thermal treatment at high temperature (~200–250°C). The benzyl chloride group of the PVBC‐based materials offers a significant potential for further elaboration and practical applications, since they can be further functionalized while retaining their integrity. This potential is demonstrated here through hydrolysis to obtain hydroxyl‐functionalized three‐dimensional networks. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43297.  相似文献   

10.
New composite polymer gels were obtained from cellulose triacetate (CTA), N‐methyl‐N′‐propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr1,3TFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). Analysis by differential scanning calorimeter and scanning electron microscope showed that the ionic gel consisting of CTA, Pyr1,3TFSI, and LiTFSI formed a completely homogeneous phase at the molar ratio of CTA/Pyr1,3TFSI/LiTFSI = 1/3/1.5. The ionic conductivity of the polymer gel was significantly enhanced by the presence of LiTFSI. FTIR study strongly implies that the interaction of lithium ion with the carbonyl group of CTA could be responsible for the increase in conductivity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

11.
Crosslinked castor oil (CO)‐based waterborne polyurethane was synthesized from CO, polycarbonate diol, isophorone diisocyanate, 2,2‐dimethylol propionic acid, and 2‐amino‐2‐(hydroxymethyl)‐1,3‐propanediol (THAM) using pre‐polymer process. Fourier transform infrared spectroscopy, X‐ray diffraction, and transmission electron microscopy were utilized to characterize the above‐synthesized polyurethane. The effect of THAM content was studied on particle size, zeta potential, thermogravimetric analysis, differential scanning calorimetry, tensile tests, and contact angle measurement. Results showed that, with the increase of THAM content, the particle size increases and the thermal stability increases. Furthermore, as the THAM content increased from 0% to 1.5%, tensile strength increased from 9.5 to 16.3 MPa, contact angle increased from 67.8° to 87.4°, and bibulous rate decreased from 13.4% to 6.1%, the elongation at break dropped from 154.8% to 37.9%, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45532.  相似文献   

12.
Thermally and UV crosslinked poly[propargyl(3‐methoxy‐4‐propargyloxy) cinnamate] (PPOF) were investigated in terms of their physical, thermal, optical, and gas‐permeation properties. The crosslinked membranes had high gel contents because of the formation of a diacetylene network. The wide‐angle X‐ray diffraction patterns showed that all of the membranes were amorphous in structure, regardless of the type of crosslinking reaction. The membrane density increased after the crosslinking reaction; this suggested that the free volume of the crosslinked membrane was lower than that of the untreated membranes. Drastic color changes in the membranes were also observed because of the highly conjugated crosslinked network of diacetylene. In addition, the conjugation caused by diacetylene crosslinking led to visible absorption within the range 400–600 nm. The gas permeation of the crosslinked membrane was reduced compared with that of the untreated membranes. In particular, the gas permeability of the thermally crosslinked membrane was lower than that of UV‐irradiated membrane. On the basis of this result, the degree of crosslinking by thermal treatment was higher than that of UV irradiation. Hence, the crosslinked PPOF membranes showed improved gas‐barrier properties due to the high conjugation of the crosslinked diacetylene network induced by thermal treatment and UV irradiation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

13.
2,6‐Di(4′‐azidobenzylidene)‐methylcyclohexanone (ABC) was one of the most used photoinitiators in negative photoresists industry, rendering insolubility of the resist films at short UV exposure times (several minutes). Although the photodecomposition of aromatic azides is very well established, the peculiarities of the irradiation medium impose specific reaction pathways for arylnitrenes. In this study, photoreactions of arylnitrenes resulted from ABC photolysis were applied in the photoinitiated crosslinking of 1,2‐polybutadiene (1,2‐PB), under soft monochromatic UV irradiation (365 nm). To elucidate the crosslinking mechanism, studies on a model compound were performed. 3‐Methyl‐1‐butene was chosen to simulate the monomeric unit of 1,2‐PB. As a support in photoproducts identifying and with the purpose of a deeper investigation of the ABC photochemistry alone, ABC was photolysed in a rigid matrix of poly(methyl methacrylate). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44694.  相似文献   

14.
Crosslinked guar gum‐g‐polyacrylate (cl‐GG‐g‐PA) superabsorbent hydrogels were prepared to explore their potential as soil conditioners and carriers. The hydrogels were prepared by in situ grafting polymerization and crosslinking of acrylamide onto a natural GG followed by hydrolysis. Microwave‐initiated synthesis under the chosen experimental conditions did not exhibit any significant improvement over the conventional technique. The optimization studies of various synthesis parameters, namely, monomer concentration, crosslinker concentration, initiator concentration, quantity of water per unit reaction mass, particle size of backbone, and concentration of alkali were performed. The hydrogels were characterized by wide‐angle X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and solid‐state 13C‐NMR spectroscopy. Swelling behavior of a candidate hydrogel [GG‐superabsorbent polymer (SAP)] in response to external stimuli, namely, salt solutions, fertilizer solutions, temperature, and pH, was studied. The GG‐SAP exhibited significant swelling in various environments. The effect of GG‐SAP on water absorption and the retention characteristics of sandy loam soil and soil‐less medium were also studied as a function of temperature and moisture tensions. The addition of GG‐SAP significantly improved the moisture characteristics of plant growth media (both soil and soil‐less), showing that it has tremendous potential for diverse applications in moisture stress agriculture. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41060.  相似文献   

15.
Polyvinyl alcohol(PVA) bead crosslinked with boric acid has been widely utilized as a microorganism immobilization carrier. However, it has some disadvantages such as drastic cell viability loss, small adsorption capacity and mass transfer limitation. To improve upon these drawbacks, a new method to prepare PVA composite pieces with the addition of activated carbon (AC) and poly‐3‐hydroxybutyrate(PHB) was explored through a combination of freezing/thawing and the boric acid method and by using Tween‐80 to improve the mass transfer performance of hydrophobic organics. m‐Cresol and pyrene were used as representative compounds with benzene ring structures to model hydrophilic and hydrophobic organics in order to test the performance of PVA pieces. The results showed that, compared with the boric acid method alone, a combination of freezing/thawing and the boric acid method led to a decrease in total organic carbon(TOC) loss from 0.315 g g?1 to 0.033 g g?1 and increased the oxygen uptake rate(OUR) of microorganisms from 0.03 mg L?1·min?1 to 0.22 mg L?1 min?1. The m‐cresol equilibrium adsorption amount of the PVA‐SA(sodium alginate)‐PHB‐AC piece was 2.80 times that of the PVA‐SA piece. The diffusion coefficient of pyrene in the PVA‐SA‐PHB‐AC piece increased from 0.53×10?9 m2 min?1 to 2.30×10?9 m2 min?1 with increasing concentrations of Tween‐80 from 1000 mg L?1 to 5000 mg L?1. The PVA‐SA‐PHB‐AC composite carrier demonstrated great scope for immobilizing microorganisms for practical wastewater bio‐treatment. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39837.  相似文献   

16.
Superabsorbent composites based on chitosan‐g‐poly(acrylamide) and montorillonite (CTS‐g‐PAAm/MMT) were synthesized through in situ radical polymerization by grafting of crosslinked acrylamide onto chitosan backbone in presence of MMT at different contents. The formation of the grafted network was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetery (DSC). The obtained porous structure was observed by scanning electron microscope (SEM). The presence of clay and its interaction with chitosan‐g‐poly(acrylamide) (CTS‐g‐PAAm) matrix was evidenced by ATR‐FTIR analysis. The morphology was investigated by both X‐ray diffraction (XRD) and SEM analyses. It was suggested the formation of mostly exfoliated structures with more porous structures. Besides, the thermal stability of these composites, observed by TGA analysis, was slightly affected by the clay loading as compared to the matrix. These hydrogel composites were also hydrolyzed to achieve anionic hydrogels with ampholytic properties. Swelling behaviors were examined in doubly distilled water, 0.9 wt % NaCl solution and buffer solutions. The water absorbency of all superabsorbent composites was enhanced by adding clay, where the maximum was reached at 5 wt % of MMT. Their hydrolysis has not only greatly optimized their absorption capacity but also improved their swelling rate and salt‐resistant ability. The hydrolyzed superabsorbent showed better pH‐sensitivity than the unhydrolyzed counterparts. The results of the antibacterial activity of these superabsorbents composites against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), assayed by the inhibitory zone tests, have showed moderate inhibition of the bacteria growth. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39747.  相似文献   

17.
A novel organic–inorganic hybrid of epoxycyclohexyl polyhedral oligomeric silsesquioxane (e‐POSS)–grafted carboxylic methoxypolyethylene glycols (mPEG‐COOH), that is, a POSS‐mPEG graftomer, was synthesized. The grafting reaction of e‐POSS and mPEG‐COOH was characterized by Fourier transform infrared (FTIR) and 1H‐NMR spectroscopy. Then the graftomer was used to develop new composite solid polymer electrolyte (SPE) films with a carboxylated nitrile rubber–epoxidized natural rubber (XNBR‐ENR) self‐crosslinked blend system as a dual‐phase polymer matrix. The self‐crosslinked reaction of the XNBR‐ENR matrix was investigated using ATR‐FTIR. The morphology of the SPE films and the distribution of lithium salt were investigated using field emission scanning electron microscopy and X‐ray diffraction, and the result illustrated that the addition of POSS‐mPEG could promote and accelerate the dissociation of LiClO4. The best effect within the range of this study was achieved when 25 phr POSS‐mPEG was involved. The differential scanning calorimetry analysis proved that the glass‐transition temperature of the composite SPE films was reduced with the increase of POSS‐mPEG. The ionic conductivity of the composite SPE films was investigated by electrochemical impedance spectroscopy. The highest ionic conductivity in this study of 2.57 × 10?5 S cm?1 was obtained with 25 phr POSS‐mPEG loading. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44460.  相似文献   

18.
Crosslinked polymer electrolyte networks were prepared from poly(ethylene glycol) diglycidyl ether blended with an epoxy resin (diglycidyl ether of bisphenol A) in different ratios and then cured with α,ω‐diamino poly(propylene oxide) in the presence of lithium perchlorate (LiClO4) as a lithium salt. The ionic conductivities of these polymer electrolytes were determined by alternating current (AC) impedance spectroscopy. Propylene carbonate (PC) was used as a plasticizer to form gelled polymer electrolyte networks. The conductivities of the polymer electrolytes containing 46 wt % PC plasticizer were approximately 5 × 10?4 S cm?1 at 25°C and approximately 10?3 S cm?1 at 85°C. These polymer electrolytes were homogeneous and exhibited good mechanical properties. The effects of the polymer composition, plasticizer content, salt concentration, and temperature on the ionic conductivities of the polymer electrolytes were examined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1264–1270, 2004  相似文献   

19.
The thermosensitive polyelectrolytes were obtained by grafting 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) onto hydroxypropylcellulose (HPC), a biodegradable polysaccharide. The interactions of the polymers with dodecyltrimethylammonium chloride (DTAC), a model cationic surfactant, were studied. It was found by the measurements of the surface tension and the analysis of fluorescence emission of pyrene used as a fluorescent probe, that the HPC–AMPS graft polymers strongly interact with DTAC with the formation of polymer–surfactant complexes. The critical aggregation concentrations of these polymer–surfactant systems were found to be of the order of 10?5 mol/dm3. The polymers were found to be potentially useful in the purification of water from cationic surfactants. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2401–2407, 2006  相似文献   

20.
The hybrid plasticized polymer electrolyte composed of the blend of poly(vinyl chloride) (PVC) and poly(acrylonitrile) (PAN) as host polymer, propylene carbonate as plasticizer, and LiClO4 as a salt was studied. An attempt was made to optimize the polymer blend ratio. XRD, Fourier transform infrared, and DSC studies confirm the formation of polymer–salt complex and miscibility of the PVC and PAN. The electrical conductivity and temperature dependence of ionic conductivity of polymer films are also studied and reported here. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

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