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1.
A simple method was used to synthesize poly(2-aminophenol), poly(2-aminophenol-co-Aniline) and polyaniline nanocomposites with sodium-montmorillonite (Na-M) using in situ intercalative oxidative polymerization. Morphology and thermal properties of the synthesized nanocomposites were examined by transmission electron microscopy (TEM) and thermogravimetric analysis. The thermal analysis shows an improved thermal stability of the nanocomposites in comparison with the pure poly(2-aminophenol). The intercalation of polymers into the clay layers was confirmed by X-ray diffraction studies, TEM images and FTIR spectroscopy. In addition, the room temperature conductivity values of these nanocomposites varied between 8.21 × 10?5 and 6.76 × 10?4 S cm?1. The electrochemical behavior of the polymers extracted from the nanocomposites, has been analyzed by cyclic voltammetry. Good electrochemical response has been observed for polymer films; the observed redox processes indicate that the polymerization into Na-M produces electroactive polymers.  相似文献   

2.
To improve water wettability of polyurethane (PU), graft copolymerization with acrylic acid (AA) and crotonic acid (CA) was performed using a benzoyl peroxide (BO) initiator. The grafting reaction was carried out by placing the membranes in aqueous solutions of AA and CA at constant temperatures. Variations of graft yield with time, temperature, initiator, and monomer concentrations were investigated. The optimum temperature, polymerization time, monomer, and initiator concentrations for AA were found to be 70°C; 3 h; 1.5 M; 5.0 × 10?2 M, and for CA 70°C; 1 h; 1.5 M; 4.0 × 10?2 M, respectively. The grafting membranes were characterized by FTIR spectroscopy and scanning electron microscopy (SEM) analysis, and the effect of grafting on equilibrium water content (EWC) of PU membranes was obtained by swelling measurements. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2690–2695, 2001  相似文献   

3.
Unreported graft copolymer of N,N′‐dimethylacrylamide (DMA) with partially carboxymethylated guar gum (CmgOH) has been synthesized and the reaction conditions have been optimized for affording maximum grafting using a potassium peroxymonosulphate (PMS)/thiourea (TU) redox initiators under nitrogen atmosphere. The study of graft copolymerization has been performed to observe maximum value of grafting parameters except percentage of homopolymer by varying the concentrations of DMA, PMS, and TU. The grafting parameters increase continuously on increasing the concentration of DMA from 8 × 10?2 to 24 × 10?2 mol dm?3, PMS from 5 × 10?3 to 21 × 10?3 mol dm?3, and TU from 1.6 × 10?3 to 4.8 × 10?3 mol dm?3. The optimum temperature and time for grafting of DMA onto CmgOH were found to be 35°C and 120 min, respectively. The water‐swelling capacity of graft copolymer is investigated. Flocculation property for both coking and noncoking coals is studied for the treatment of coal mine waste water. The graft copolymer is characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

4.
Polysaccharide based graft copolymer (xanthan gum‐g‐4‐vinyl pyridine) was synthesized using potassium peroxymonosulphate/ascorbic acid redox initiator in inert atmosphere at 40°C. By studying the effect of the concentration of monomer, peroxymonosulphate (PMS), ascorbic acid (AA), xanthan gum (XOH), hydrogen ion along with effect of time and temperature on grafting characteristics: grafting ratio (%G), add on (%A), conversion (%C), efficiency (%E), homopolymer (%H), and rate of grafting (Rg), the reaction conditions for optimum grafting were determined. The optimum concentration of AA, H+ ion, 4‐VP for maximum grafting were found to be 10.0 × 10?3 mol dm?3, 2.5 × 10?2 mol dm?3, 10.0 × 10?3 mol dm?3, respectively. Maximum %G was obtained at minimum concentration of xanthan gum i.e., at 40.0 × 10?2 g dm?3 and at maximum concentration of PMS i.e., at 10.0 × 10?3 mol dm?3. The optimum temperature and time duration of reaction for maximum % of grafting were found to be 45°C and 120 min respectively. The synthesized graft copolymer was characterized by FTIR analysis. Thermogravimetric analysis showed that the xanthan gum‐g‐4‐vinyl pyridine is thermally more stable than pure gum. A probable mechanism was suggested for the graft copolymerization. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

5.
In the present article, the graft copolymerization of 4‐vinyl pyridine onto guar gum initiated by potassium peroxymonosulphate/ascorbic acid redox pair in an aqueous medium was studied gravimetrically under a nitrogen atmosphere. Grafting ratio, grafting efficiency, and add on increased on increasing the concentration of potassium peroxymonosulphate from 5.0 × 10?4 to 10 × 10?4 mol/L and ascorbic acid concentration from 0.4 × 10?3 to 2.0 × 10?3 mol/L. On increasing the hydrogen ion concentration from 2.5 × 10?3 to 10.0 × 10?3 mol/L, grafting ratio, efficiency, add on and conversion were increased. Maximum grafting was obtained when guar gum and monomer concentration were 1.0 g/L and 20.0 × 10?2 mol/L, respectively. An increase in temperature from 30 to 35°C increased the grafting ratio, but conversion and homopolymer decreased. The graft copolymers were characterized by IR spectroscopy and thermogravimetric analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

6.
Graft copolymerization of methyl methacrylate (MMA) onto oil palm empty fruit bunch fiber (OPEFB) was successfully carried out in aqueous medium using hydrogen peroxide as an initiator. Results from the investigation of the optimum conditions for grafting are presented. Maximum percentage of grafting was achieved when the amount of initiator, cocatalyst, and nitric acid were 5.877 × 10?3 mol, 2.63 × 10?4 mol, and 3.24 × 10?3 mol, respectively. The optimum reaction temperature was 50°C and the reaction period was 120 min. The highest percentage of grafting and grafting efficiency were 220 and 47%, respectively, under optimum conditions. The grafted copolymer was characterized by FTIR spectroscopy and scanning electron microscopy. The presence of a band at 1730 cm?1 provides strong evidence of grafting. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2233–2238, 2003  相似文献   

7.
Hydroxyethyl methacrylate (HEMA) was grafted onto chitosan membranes by plasma‐graft polymerization. Effects of monomer concentration, plasma power and plasma time on the amount of grafting were investigated. The results showed that there were two processes: grafting polymerization and etching of the membrane. The surface of the grafted membrane was evaluated by FTIR. Scanning electron microscopy indicated that the surface morphology of the grafted membrane could be adjusted through plasma power. Water contact angles of the chitosan surface decreased from 78.2° to 45.4° while the amount of grafting increased from 0 to 12.2%, indicating improved hydrophilicity of the membrane surface. Permeation coefficients through the original membrane, the membrane treated at 55 W for 15 min, and the membrane treated at 55 W for 30 min for creatinine were 9.12 × 10?7, 10.6 × 10?7 and 8.57 × 10?7 cm2 s?1, respectively. Thermogravimetry and mechanical testing showed that there were no significant changes on the bulk property of chitosan membrane after modification. © 2003 Society of Chemical Industry  相似文献   

8.
A post‐polymerization method for metal–organic frameworks (MOFs) has been developed to produce super‐acidic solid nanoparticles. Thus, the NH2MIL‐53(Al) MOF was functionalized with (3‐aminopropyl)triethoxysilane (APTES) from amine groups to yield active site anchored MOF nanoparticles. Then, sulfonated polymer/MOF hybrid nanoparticles were prepared by redox polymerization of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (MOF‐g‐PAMPS), initiated onto the surfaces of aminopropyl‐functionalized NH2MIL‐53(Al) nanoparticles. The synthesis and modification of NH2MIL‐53(Al) nanoparticles were characterized by Fourier transform infrared (FTIR) spectroscopy and TGA. FTIR and TGA results indicated that APTES modifier agent and AMPS monomer were successfully grafted onto the MOF nanoparticles. The grafting efficiency of PAMPS polymer onto the MOF nanoparticles was estimated from TGA thermograms to be 33%. Also, sulfonated polymer/MOF hybrid nanoparticles showed a proton conductivity as high as 4.9 × 10?5 S cm?1. Nitrogen adsorption of modified NH2MIL‐53(Al) showed also a decrease in pore volume. The morphology and crystalline structure of MOF nanoparticles before and after the modification processes were studied by SEM and XRD, respectively. © 2015 Society of Chemical Industry  相似文献   

9.
In this article, graft copolymerization of N‐vinyl‐2‐pyrrolidone onto xanthan gum initiated by potassium peroxydiphosphate/Ag+ system in an aqueous medium has been studied under oxygen free nitrogen atmosphere. Grafting ratio, grafting efficiency, and add on increase on increasing the concentration of potassium peroxydiphosphate (2.0 × 10?3 to 12 × 10?3 mol dm?3), Ag+(0.4 × 10?3 to 2.8 × 10?3 mol dm?3), and hydrogen ion concentration from 2 × 10?3 to 14.0 × 10?3 mol dm?3. Maximum grafting has been obtained when xanthan gum and monomer concentration were 0.4 g dm?3 and 16 × 10?2 mol dm?3, respectively, at 35°C and 120 min. Water swelling capacity, swelling ratio, metal ion uptake, and metal retention capacity have also been studied, and it has been found that graft copolymer shows enhancement in these properties than pure xanthan gum. The graft copolymer has been characterized by FTIR and thermal analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

10.
Kaolinite clay (KC) surface was modified with different surface modifiers such as methacrylic acid (MAA), polymethacrylic acid (PMAA1, mol wt 10,000) and polymethacrylic acid (PMAA2, mol wt 11,500). The adsorption isotherms of the above modifiers on the surface of KC were determined. The concentrations required for building up monolayer coverage of these modifiers on the surface of KC were determined from the adsorption isotherms. The optimum amount of modifier required for monolayer surface coverage on kaolinite was equal to 31 × 10?5 mol/g for MAA, 35 × 10?5 mol/gfor PMAA and 23.5 × 10?5 mol/g for PMA. Different rubber mixes containing unmodified and modified KC were prepared. The rheometric characteristics of the rubber mixes and physico-mechanical properties of the rubber vulcanizates were measured. There was remarkable decrease in both the optimum cure time (tc90) and scorch time (ts2), following increase in the maximum torque of the SBR mixes by adding unmodified or modified KC. With the maximum torque increase, the values of both of the optimum cure time (tc90) and scorch time (ts2) decreases for the NR mixes by adding unmodified and modified KC. Also the mechanical properties of the investigated rubber vulcanizates as tensile strength and hardness were improved using unmodified KC and modified KC.  相似文献   

11.
Graft copolymerization of glycidyl methacrylate (GMA) onto cellulose filter paper (CFP) was carried out by a free‐radical initiating process using ceric ammonium nitrate (CAN) as an initiator. Optimum conditions pertaining to different grafting percentages were evaluated as a function of monomer and initiator concentrations, polymerization time and temperature. CFP with various graft levels of GMA was characterized by fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis (TGA). Surface morphology of ungrafted and grafted CFP was evaluated by scanning electron microscopy (SEM). Attenuated total reflectance (ATR)‐FTIR spectral analysis provided the evidence of grafting of GMA onto CFP. The maximum grafting of 102% was achieved by using 4 × 10?3 molL?1 CAN and 5% of GMA (w/v) monomer at 60°C in 25 min. The CFP‐g‐GMA surfaces with different graft levels were evaluated as a support for immobilization of biomolecules. Urease was selected as the model enzyme to be covalently coupled through the surface epoxy groups of the CFP‐g‐GMA discs. Immobilized discs were further studied for urea estimation and their reusability. Although the highest degree of urease immobilization was observed at 100% (162‐μg urease/disc) graft level, the urease immobilized on discs with 70% (105‐μg urease/disc) graft level gave the maximum activity of the enzyme. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

12.
The monomer, 4-acrylamidobenzenesulfonamide (ABS), was synthesized via reaction of acryloyl chloride with 4-aminobenzenesulfonamide in acetone at 0 °C. This monomer was then grafted onto chitosan using solution containing 2% acetic acid and mixture of K2S2O8 and Na2SO3 as the redox promoter. An optimal G% of 150% was obtained when the process is conducted at 60 °C for 3 h employing 3.0 × 10?3 M K2S2O8 and 1.5 × 10?3 M Na2SO3. The graft copolymers, chitosan-g-poly(4-acrylamidobenzenesulfonamide), were characterized by using FTIR, XRD, and SEM. The results were shown that the crystallinity of chitosan is enhanced by increasing the monomer content through the grafting process. Potential Antimicrobial activities of the permethyl ammonium salt forms of chitosan and its grafted copolymers against selected microorganisms were evaluated. The results show that the graft copolymers display better inhibitory effects on the growth of bacteria and some fungi than does chitosan.  相似文献   

13.
The graft copolymerization reaction of acrylamide onto guar gum with a vanadium(V)/mandelic acid redox pair was carried out in an N2 atmosphere. The optimum concentrations of vanadium(V), mandelic acid, hydrogen ions, acrylamide, and guar gum for the maximum percentage of grafting were 6.0 × 10?3, 2.0 × 10?2, 55.0 × 10?2, and 20.0 × 10?2 mol/dm3 and 110.1 × 10?2 g/dm3, respectively. The optimum time and temperature of reaction were 90 min and 35°C, respectively, and during the study of [H+] variation, a prompt change in the value of the grafting parameters was observed. The maximum percentage of swelling of the graft copolymer was achieved at room temperature in 1 h. Studies of the flocculation, viscosity, and metal‐ion absorption capacity were also performed. The synthesized graft copolymer was characterized by Fourier transform infrared spectroscopy and thermogravimetric analyses, which showed that the grafted guar gum was thermally more stable than the ungrafted guar gum. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

14.
A novel redox system, tert‐butyl hydroperoxide (TBHP)–silk sericin (SS), was used to initiate the graft copolymerization of methyl acrylate (MA) onto silk sericin in an aqueous medium. The graft copolymer, consisting of nanoparticles with a fine core–shell structure, was characterized using Fourier transfer infrared spectroscopy. The effects of the concentrations of MA and TBHP, reaction temperature and time on the grafting parameters of the copolymerization were studied in detail. In terms of grafting percentage and grafting efficiency, the optimum reaction conditions were obtained as follows: [MA] = 0.465 mol L?1, [TBHP] = 3.884 × 10?4 mol L?1, T = 80 °C, t = 150 min. Transmission electron microscopy images of the particles showed a core–shell morphology, where poly(methyl acrylate) cores were covered with SS shells. A possible initiation mechanism is proposed. Copyright © 2006 Society of Chemical Industry  相似文献   

15.
A glassy carbon electrode (GCE) modified with poly(sulfosalicylic acid) (PSA) and poly(diallyldimethylammonium chloride)-graphene (PDDA-GN) was prepared by a simple self-assembly method. The formation of films was ascribed to the electrostatic force between negatively charged PSA and positively charged PDDA-GN as well as the π–π stacking interaction between PSA and PDDA-GN. The as prepared films were characterized by scanning electron microscopy (SEM), Raman spectroscopy and electrochemical methods. Under the optimized condition, the modified GCE showed two well-defined redox waves for catechol (CT) and hydroquinone (HQ) in cyclic voltammetry (CV) with a peak potential separation of 111 mV, which ensured the anti-interference ability of the electrochemical sensor and made simultaneous determination of dihydroxybenzene isomers possible in real samples. The corresponding oxidation currents increased remarkably compared with those obtained at the bare GCE, PSA/GCE and PDDA-GN/GCE, respectively. Differential pulse voltammetry (DPV) was used for the simultaneous determination of CT and HQ. The anodic peak current of CT was linear in the concentration from 1 × 10?6 to 4 × 10?4 M in the presence of 3 × 10?5 M HQ, and the detection limit was 2.2 × 10?7 M (S/N = 3). At the same time, the anodic peak current of HQ was linear in the concentration from 2 × 10?6 to 4 × 10?4 M in the presence of 2 × 10?5 M CT, and the detection limit was 3.9 × 10?7 M (S/N = 3). The proposed method was applied to simultaneous determination of CT and HQ in tap water with satisfactory results. These results indicated that PSA/PDDA-GN is a promising modified material with great potential in electrocatalysis and electrochemical sensing.  相似文献   

16.
The graft copolymerization was carried out by methyl methacrylate with starch in which azobisisobutyronitrile was used as an initiator. The grafting reactions were carried out within a 65–95°C temperature range, and the effect of the monomer, initiator concentrations, and the amount of starch on the graft yield were also investigated. The maximum graft yield was obtained at a azobisisobutyronitrile concentration of 2.0 × 10?3 mol/L. The overall rate activation energy of the reaction was found to be 89.42 kJ/mol. The grafted starches were characterized with infrared spectroscopy, scanning electron microscopy, and thermogravimetry. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 53–57, 2002  相似文献   

17.
In this study, grafting of itaconic acid (IA) onto sodium alginate (NaAlg) using cerium(IV) ammonium nitrate/nitric acid (CAN/HNO3) as redox system was carried out by free radical polymerization. The structures of the grafted copolymers (NaAlg-g-PIA) were characterized by ATR-FTIR spectroscopy, NMR spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The reaction conditions for maximum grafting were optimized by varying the reaction time, temperature, percentage of sodium alginate, monomer, initiator, and nitric acid concentrations. The optimum reaction conditions were obtained with reaction time of 5 h, reaction temperature of 30 °C, IA concentration of 0.92 M, CAN concentration of 1.368 × 10?1 M, HNO3 concentration of 0.094 M and percentage of NaAlg 0.5 g/dL. The solubility test of NaAlg-g-PIA was also investigated using solvents. The results indicate that prepared graft copolymer was non-soluble in the various solvents, while it was soluble only in saturated solution of NaOH and promising as an adsorbent.  相似文献   

18.
In this paper, nanoporous nickel phosphate VSB-5 nanorods was synthesized with microwave irradiation and hydrothermal treatment and characterized by X-ray diffraction, FT-IR spectroscopy, Filed emission scanning electron microscopy (FESEM) and EDS analysis. FESEM technique exhibited the presence of nickel phosphate nanorods morphology. The BET surface area, total pore volume and average pore diameter of synthesized nickel phosphate were obtained to be 102.5 m2 g?1, 0.14 cm3 g?1 and 3.6 nm, respectively. Carbon paste electrode (CPE) was modified by VSB-5 nanorods and then Ni2+ ions incorporated to this electrode to obtain Ni-VSB-5/CPE. The current intensity of glucose oxidation increases impressively on the surface of Ni-VSB-5/CPE and modified CPE can reduce the overvoltage of glucose oxidation in comparison with Ni-CPE. The values of electron transfer coefficient, diffusion coefficient and mean value of catalytic rate constant for glucose and redox sites of electrode were found to be 0.87, 6.18 × 10?4 cm2 s?1 and 3.06 × 105 cm3 mol?1 s?1, respectively. The good catalytic activity, high sensitivity, good selectivity and stability and ease of preparation rendered the Ni-VSB-5/CPE to be a capable electrode for glucose electro-oxidation.  相似文献   

19.
《分离科学与技术》2012,47(11):1750-1766
The present article reports results of the studies on adsorptive removal of catechol and resorcinol from aqueous solution by granular activated carbon (GAC). Physico-chemical characterization including surface area, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) of the GAC before and after catechol and resorcinol adsorption have been done to understand the adsorption mechanism. Bulk density and heating value of GAC were found to be 725 kg/m3 and 8.26 MJ/kg, respectively. The BET surface area was 977.6 m2/g whereas the BET average pore diameter was 18.79 Å. Different experimental parameters like initial pH, initial dosage, contact time, and initial concentration were evaluated for their effect on the adsorption of catechol and resorcinol onto GAC. The kinetics of adsorption was found to be described by the pseudo-second order equation. Results of the intra-particle diffusion model show that the pore diffusion is not the only rate limiting step. The effective diffusion coefficient of catechol and resorcinol were of the order of 2.9 × 10?10 and 2.2 × 10?10 m2/s.  相似文献   

20.
A graft copolymer based on a polysaccharide (sodium salt of carboxymethylcellulose) and a vinyl monomer (acrylamide) has been synthesized in a nitrogen atmosphere, and its reaction conditions have been optimized for a better yield with ferrous sulfate and potassium bromate as a redox initiator. The effects of ferrous ion, bromate ion, hydrogen ion, sodium carboxymethylcellulose, and acrylamide along with the reaction time and temperature have been studied through the determination of the grafting parameters: the grafting ratio, add‐on, conversion, efficiency, homopolymer, and rate of grafting. The maximum yield has been found to occur when the acrylamide concentration is 8.0 × 10?2 mol/dm3, whereas the maximum conversion occurs at a minimum concentration of acrylamide, that is, at 3.0 × 10?2 mol/dm3. The grafting parameters have been found to increase with an increasing concentration of the redox initiator (Fe2+, from 2.0 × 10?3 to 10.0 × 10?3 mol/dm3; BrO, from 2.2 × 10?3 to 4.0 × 10?3 mol/dm3). The maximum efficiency occurs with a reaction time of 210 min. The rate of grafting has been found to be maximum up to 60 min; after that, it decreases rapidly. In this article, it is shown that the hydrogen ion leads to a very clear decrease in the grafting parameters as its concentration increases from 2.1 × 10?3 to 11.3 × 10?3 mol/dm3. Grafted gum and ungrafted gum have been characterized with Fourier transform infrared spectroscopy and thermogravimetric analysis. A probable mechanism has been suggested for graft copolymerization. It has been observed that the graft copolymer is thermally more stable than the parent backbone. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

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