Aqueous Polymerization Of Acrylonitrile Research Articles

Catalytic Polymerization of Acrylonitrile by Khulays Bentonite

The aqueous polymerization of acrylonitrile (AN) catalyzed with exchanged Khulays bentonite . The influence of various polymerization parameters ( e.g., concentrations of Potassium Persulfate (K2S2O8) and monomer , various of organic solvents, and different temperature has been investigated. It was found that the rate of polymerization of AN was found to be dependent on monomer concentration, initiator and temperature. The activation energy of polymerization was calculated .Thermal properties of the polymer were studied by TGA and DSC techniques. © 2007 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

Kinetics and mechanism of the K2CrO4NaAsO2 redox‐initiated aqueous polymerization of acrylonitrile

AbstractThe kinetics and mechanism of acrylonitrile polymerization initiated by a redox pair [potassium chromate (K2CrO4) and sodium arsenite (NaAsO2)] were studied. The overall rate of polymerization was proportional to √[K2CrO4] × [NaAsO2], and the energy of activation was approximately 10.5 kJ/mol. Polyacrylonitrile was recovered as a coagulum in the medium. The formation of polyacrylonitrile was confirmed with Fourier transform infrared and 1H‐NMR analyses. Scanning electron microscopy analysis of the polymer revealed the formation of aggregates of polymer particles (3–67 nm). Thermogravimetric studies indicated 50% weight loss at 400°C, and dynamic thermal analysis scan studies revealed an exothermic peak at 507°C due to massive oxidative thermal degradation of the polyacrylonitrile backbone. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 276–280, 2005

Studies on Aqueous Polymerization of Acrylqnitrile Initiated by Ce(IV)-DMSO

Abstract Aqueous polymerization of acrylonitrile initiated by the Ce(IV)-DMSO redox system was studied in the temperature range of 40°-60°C. The rate of polymerization R p was found to be approximately proportional to [M]3/2 within the range of monomer concentration of 0.32–1.2 mL-1. Effects of time and concentration of Ce(IV), DMSO, H2SO4, and salts were studied. The overall activation energy for the polymerization reaction was estimated to be 4.606 kcal/mol. A suitable kinetic scheme was proposed in the light of these experimental results. Kinetic analysis shows that the mutual termination predominates over linear termination.

Aqueous polymerization of acrylonitrile initiated by manganese(III) pyrophosphate-thiocyanate redox system: a kinetic study

The kinetics of aqueous polymerization of acrylonitrile monomer (M) initiated by the MnIII-KNCS redox system have been studied under deaerated conditions in the temperature range 26–40 °C at constant ionic strength. The overall rates of polymerization and the disappearance of MnIII were determined. The polymerization was initiated by the free radicals arising from the MnIII-thiocyanate redox reaction. The rate of polymerization was investigated at various concentrations of monomer and initiator. The effects of varying [MnIII], [NCS−], pH, total [P2O inf7 sup4− ], added [MnII], metal ions, ClO inf4 sup− , Cl− and SO inf4 sup2− were examined. Dependence of the rate of polymerization on temperature was studied and activation parameters were computed from an Arrhenius plot. A suitable kinetic scheme consistent with the observed results is proposed and discussed.

Polyacrylonitrile (PAN)‐grafted jute fibres: Some physical and chemical properties and morphology

AbstractGrafting of polyacrylonitrile (PAN) on (dewaxed and bleached) jute fibres was done by aqueous polymerization of acrylonitrile (AN) in the presence of the fiber samples employing a sodium periodate (IO4−) and copper sulfate (Cu2+) combination as the initiator. Effect of PAN grafting to different extents on X‐ray crystallinity, tensile properties, thermal behavior, whiteness index, dyeability, light‐fastness rating, and moisture regain properties of the fiber samples were studied and analyzed. Their rot resistance, determined by a standard soil burial test, were also examined and compared. Twenty to thirty percent PAN‐grafting was found to impart a most desirable balance of physical properties including fiber strength and modulus, moisture regain, whiteness index, and light‐fastness rating. PAN grafting also makes the otherwise nonresistant jute fiber significantly rot‐resistant. Morphology of the different fiber samples as studied and compared using scanning electron microscopy indicates that PAN grafting occurs on surfaces and intercellular regions as well as within the lumens of the multicellular jute fibers. © 1994 John Wiley & Sons, Inc.

The redox aqueous polymerization of acrylonitrile under pressure

AbstractEffect of pressure (atmospheric to 20 X 106 Pa) on the K2S2O8–Na2S2O4 initiated aqueous polymerization of acrylonitrile has been studied at 25°C. The conversion and rate of the polymerization tend to rise initially with increase of pressure and fall subsequently to a limiting value. The initial rise in the rate is consistent with an increase of kp or a decrease in kt due to high pressure. The ultimate tendency of the rate to fall is possibly due to a decrease in the diffusion rate of the monomer from the aqueous phase to the growing polymer radical site. The molecular weight shows a more or less similar trend except that the fall in the molecular weight begins at a lower pressure range than the same in the rate or conversion. This is explained on the basis of enhanced monomer transfer reaction. These observed kinetic characteristics are not sensitive to the appearance of heterogeneity in the system due to insoluble polymer phase in as much as homogeneous reaction systems in DMF or DMSO essentially exhibit the same features. The rate is proportional to the square root of the product of [K2S2O8] and [Na2S2O4] and varies linearly as the first power of the monomer concentration.

Thiols as Reducing Agents. 1. Polymerization of Acrylonitrile Initiated by the Peroxydisulfate-Thiomalic Acid Redox System

Abstract The aqueous polymerization of acrylonitrile (AN) initiated by the potassium persulfate-thiomalic acid (TMA) redox system has been studied at 35 ± 0.1°C in a nitrogen atmosphere. The rate of polymerization is governed by the expression, Rp = K[AN] [S2O8 2-]x[TMA]0.40, where x = 0.60 for lower monomer concentration md 0.75 for higher monomer concentration. The overall activation energy was found to be 7.3 kcal/mol in the investigated range of temperature. The deviations from normal kinetics are discussed, and a tentative mechanism of initiation is given. The effects of inorganic electrolytes on polymerization were also investigated.

Aqueous polymerization of acrylonitrile by ascorbic acid–peroxodisulfate redox system

AbstractThe polymerization of acrylonitrile initiated by an ascorbic acid–peroxodisulfate redox system was studied in an aqueous solution at 35°C in the presence of air. Molecular oxygen was found to have no effect on the polymerization reaction. An increase in ionic strength slightly increased the rate. The overall rate of polymerization, Rp, showed a square dependence on [monomer] and a half‐order dependence on [peroxodisulfate]. A first‐order dependence on [ascorbic acid] at low concentrations (<3.0 × 10−3 mol L−1) followed by a decrease in Rp at higher concentrations of ascorbic acid (>3.0 × 10−3 mol L−1) was also noted. Rp remained unchanged up to 40°C and showed a decline thereafter. Addition of catalytic amounts of cupric ions decreased the rate whereas ferric ions were found to increase the rate. Added sulfuric acid in the range (6.0−50.0) × 10−5 mol L−1 decreased the Rp.

Polymerization of Acrylonitrile Initiated by K2S2O8-CO(II) and K2S2O8-Mn(II) Redox Systems

Abstract The kinetics of the aqueous polymerization of acrylonitrile initiated by the peroxydisulfate-Co(II) and peroxydisulfate-Mn(II) redox systems were investigated between 40 and 60°C. The rates of polymerization were measured at various concentrations of oxidant, activator, and monomer. From the results it was concluded that the polymerization reaction is initiated by an organic free radical arising from the peroxydisulfate-Co (II) and peroxydisulfate-Mn(II) redox systems and termination by the mutual type. On the basis of experimental observations of the dependence of the rate of polymerization various variables, a suitable kinetic scheme has been proposed.

Vinyl polymerization of acrylonitrile by the Ce(IV)-glucose redox system

Aqueous polymerization of acrylonitrile (M) initiated by the Ce(IV)-glucose (R) redox system has been studied under nitrogen in the temperature range of 30–40 °C. The rate of polymerization (Rp) is proportional to [M]2, [R] and inversely proportional to [Ce(IV)]. The rate of ceric ion disappearance is proportional to [R] and [Ce(IV)]. The end group in the polymer is characterised by IR spectra. A suitable kinetic scheme has been proposed and explained in the light of these experimental findings.

Studies on Vinyl Polymerization: Polymerization of Acrylonitrile by Permanganate-Glucose Initiator System

Abstract Aqueous polymerization of acrylonitrile initiated by the permanganate-glucose system has been studied under atmospheric conditions at 35 to 45°C. The rate of polymerization (Rp) is maximum at an optimum concentration of activator, but directly proportional to the concentration of monomer. Rp increases with an increase of metal ion concentration to a certain value and then decreases with a further increase of metal ion concentration. The effects of various water-soluble salts and solvents have been investigated. The end group of the polymer has been characterized by IR spectra. A suitable kinetic scheme has been proposed, appropriate rate expressions have been derived, and they are explained in the light of the experimental findings.

Vinyl Polymerization Initiated by Peroxydiphosphate. IV. Polymerization of Acrylonitrile Initiated by Peroxydiphosphate-Thioacetamide Redox System

Abstract The kinetics of the aqueous polymerization of acrylonitrile initiated by the peroxydiphosphate-thioacetamide redox system was investigated at 35, 40, and 50°C. The rates of polymerization were measured at different concentrations of oxidant, activator, and monomer. Peroxydiphosphate alone did not initiate polymerization under deaerated and undeaerated conditions. Addition of certain water-miscible organic solvents and neutral salts depress the rate and conversion. On the basis of experimental observations of the dependence of the rate of polymerization on various variables, a suitable kinetic scheme has been proposed.

Vinyl polymerization initiated by peroxydiphosphate

The kinetics of the aqueous polymerization of acrylonitrile and methyl methacrylate initiated by the peroxydiphosphate-thioglycollic acid redox system was investigated at 40, 45, 50, 55, and 60 °C. The rates of polymerization were measured at different concentrations of oxidant, activator and monomer. From the results, it was concluded that the polymerization reaction is initiated by an organic free radical arising from the peroxydiphosphate-thioglycollic acid system and termination by mutual type. On the basis of experimental observations of the dependence of the rate of polymerization,Rp on various variables, a suitable kinetic scheme has been proposed.

Aqueous polymerization of acrylonitrile by Ce(IV)-diacetone alcohol redox system

The kinetics of oxidation of DAA by Ce(IV) in dilute sulphuric acid medium has been studied and the reaction was found to obey a second order rate law. This DAA — Ce(IV) redox system has been used for the polymerization of acrylonitrile and the rate of polymerization was found to be proportional to[Ce(IV)]0.5, [DAA]0.5 and [M]1.5. Based on these results a probable mechanism for initiation and termination has been proposed. The chain lengths of the polymers were found to increase with [M] and decrease with both [Ce(IV)] and [DAA].

Kinetic evidence for the mechanistic difference in the aqueous polymerization of acrylonitrile

AbstractKinetic evidence indicated two different mechanistic pathways in the polymerization of acrylonitrile initiated by peroxodiphosphate‐vanadyl ion redox system in aqueous solution depending upon the concentration of the reducing metal ion employed. The mechanistic difference lies in the termination reaction, exclusively mutual termination occurring in the concentration range [VO2+]=2,5·10−3 to 5·10−3 mol·dm−3 and exclusively linear termination taking place in the concentration range [VO2+] =10−2 to 25·10−3 mol·dm−3.

Studies on aqueous polymerization of acrylonitrile. Cerium(IV)/acetaldehyde redox system

AbstractThe thermal polymerization of acrylonitrile initiated by the cerium(IV)/acetaldehyde (A) redox system was carried out at 25°C, and the rate of monomer disappearance, –d[M]/dt, was followed by gravimetry and the rate of cerium(IV) disappearance –d[Ce(IV)]/dt by titrimetry. –d[M]/dt was found to be directly proportionsl to [M]3/2, [A]1/2, and [Ce(IV)]1/2. –d[Ce(IV)]/dt was found to be directly proportional to [Ce(IV)] and [A]. A reaction scheme is given together with the kinetic expressions. The activation energy for the overall rate was found to be 67,24kJ.mol−1 (16,06kcal.mol−1), and the value of the second order rate constant kr, was obtained as 2,481.mol−1s−1.

Redox Polymerization of Acrylonitrile: Kinetics of the Reaction Initiated by the Redox System 1-Propanol—Chromic Acid

Abstract The kinetics of the aqueous polymerization of acrylonitrile initiated by the chromic acid-1-propanol redox system was investigated under a nitrogen atmosphere. The rates of polymerization and the disappearance of Cr(VI) were measured. Chromic acid alone did not initiate the polymerization under deaerated and undeaerated conditions. Water-miscible organic solvents and neutral salts depress both the rate and the conversion. On the basis of the experimental observations of the dependence of the rate of polymerization Rp and the rate of disappearance of Cr(VI)-Rm on various variables, a suitable kinetic scheme was proposed and various rate and energy parameters evaluated.

アクリルニトリルの水性重合反応次数におよぼすかきまぜの影響

アクリルニトリルの水性重合反応次数におよぼすかきまぜの影響