Copolymerization kinetics of acrylonitrile with amino ethyl‐2‐methyl propenoate in H2O/DMSO mixture

Amino ethyl‐2‐methyl propenoate (AEMP) was used successfully to copolymerize with acrylonitrile (AN). This was achieved by using azobisisobutyronitrile as the initiator. Kinetics of copolymerization of AN with AEMP was investigated in H₂O/dimethylsulfoxide (DMSO) mixture between 50 and 70 °C under N₂ atmosphere. The rate of copolymerization was measured. The kinetic equation of copolymerization system was obtained and the overall activation energy for the copolymerization system was determined. Values of monomer apparent reactivity ratios were calculated using Kelen–Tudos method. It has been found that the apparent reactivity ratios in aqueous suspension polymerization system are similar to those in solution polymerization system at polymerization conversion less than 25%. At conversion beyond 45%, the changes of monomer apparent reactivity ratios become less prominent. In water‐rich reaction medium (H₂O/DMSO > 70/30), monomer apparent reactivity ratios are approximately equivalent to those in aqueous suspension polymerization system. In DMSO‐rich reaction medium (DMSO/H₂O > 70/30), apparent reactivity ratios are similar to those in solution polymerization system. With an increase of polarity of solvent, values of apparent reaction ratios both decrease. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2095–2100, 2006     

Rheological kinetics of acrylonitrile–acrylamide copolymer solutions in dimethyl formamide

Viscosity behavior of dimethyl formamide solutions of acrylonitrile–acrylamide copolymer is discussed. The rheological kinetics of the solutions was studied for contrast. It is shown that the solutions behave the same as Newtonian flow as the rotor speed goes beyond 6 revolutions min⁻¹. With an increase of temperature, the apparent viscosity of acrylonitrile–acrylamide copolymer solutions shows a decreasing trend. The changes of the apparent flow–activation energy of solutions calculated by Arrhenius equation become less prominent along with the changes of the molecular weight of acrylonitrile–acrylamide copolymers. The apparent flow–activation energy of the copolymer solutions increases continuously with an increase of copolymer concentration. The viscosity of copolymer solutions decreases continuously at concentrations of KCl and NaCl up to 0.02 mol L⁻¹ and then increases. The apparent flow–activation energy of acrylonitrile–acrylamide copolymer solutions shows an obvious trend of decrease with addition of alkali salts and the changes of the apparent flow–activation energy of solutions containing NaCl are more prominent than those of solutions containing KCl. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 527–531, 2005     

Rheological behavior of acrylonitrile/ammonium acrylate copolymer solutions

Ammonium acrylate was first used as a comonomer to copolymerize with acrylonitrile. The viscosity behavior of dimethyl formamide solutions of acrylonitrile/ammonium acrylate copolymer was studied, and the rheological kinetics of the solutions were studied for comparison. It was shown that the solutions behaved the same as a Newtonian flow as the rotor speed increased beyond 12 rpm. With an increase in temperature, the apparent viscosity of acrylonitrile/ammonium acrylate copolymer solutions showed a trend of decreasing. The changes in the apparent flow‐activation energy of solutions (E_η) calculated by the Arrhenius equation became less prominent along with the changes in the molecular weight of the acrylonitrile/ammonium acrylate copolymers. E_η increased continuously with an increase in copolymer concentration. The viscosity of copolymer solutions decreased continuously as the concentrations of KCl and NaCl increased up to 0.015 mol/L, and then it increased. The E_η showed an obvious trend of decreasing with the addition of alkali salts, and the changes in the E_η containing NaCl were more prominent than those of solutions containing KCl. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2320–2324, 2007     

Stability of acrylonitrile/methyl vinyl ketone copolymer solutions

Methyl vinyl ketone was successfully copolymerized with acrylonitrile for the first time. This was achieved with azobisisobutyronitrile as the initiator. The viscosity behavior of solutions of the acrylonitrile/methyl vinyl ketone copolymers was determined. The solution agreed with the character of Newtonian flow at the lower shearing rate. The addition of mechanical mixing obviously prevented an increase in the viscosity of the copolymer solutions. When dimethylformamide was used as an additive, the solution viscosity decreased monotonically. When H₂O was used as an additive, the viscosity of the copolymer solutions decreased continuously with concentrations of H₂O up to 4 wt % and then increased. The viscosity of the copolymer solutions decreased continuously with concentrations of KCl and NaCl up to 0.03 mol/L and then increased. Within the first 10 h, there was a great drop in the viscosity of the copolymer solutions containing sodium ethoxide and sodium hydroxide, and then the viscosity appeared to increase. The composition with 12 wt % acetic acid in dimethyl sulfoxide could be considered to be a Θ solvent for the acrylonitrile/methyl vinyl ketone copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3377–3381, 2006     

Viscosity behavior of acrylonitrile–ammonium itaconate copolymer solutions in dimethyl sulfoxide

The viscosity behavior of dimethyl sulfoxide (DMSO) solutions of acrylonitrile–ammonium itaconate copolymer is discussed. The intrinsic viscosity was determined by an Ubbelohde viscometer. It is shown that an increase in the viscosity of acrylonitrile–ammonium itaconate copolymer solutions with time is considerably reduced by mechanical mixing. The viscosity of copolymer solutions with dimethyl formamide as an additive decreases monotonically. The viscosity of copolymer solutions decreases with the addition of H₂O, and as the content of H₂O in DMSO goes beyond 3 wt %, the viscosity shows a trend toward increase. The intrinsic viscosity decreases quickly with the addition of NaCl. As the concentration of NaCl goes beyond 0.015 mol/L, the viscosity increases solwly. The viscosity of copolymer solutions containing sodium ethoxide and sodium hydroxide appears to increase after an initial drop. The viscosity of copolymer solutions upon the addition of diethylamine increases continuously with time and changes in viscosity become less prominent after a period of a few hours. The effects of bases on the tacticity of highly isotactic copolymers follow the order of base strength. Diethylamine is more effective for moderating the stabilization exotherm of highly isotactic copolymers compared to sodium ethoxide and sodium hydroxide. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2622–2626, 2004     

Rheological aspects of fiber spinning from cellulose solutions in N‐methylmorpholine‐N‐oxide

Based on rheological experiments with a cellulose solution in N‐methylmorpholine‐N‐oxide (NMMO), it was found that the shearing stress generated in the flowing viscoelastic fluid decreases with an l/d ratio in a rheometer capillary. This reduces the elastic response and the outflow of the fluid becomes more uniform. At constant temperature, the elongational viscosity of the solidified stream of the cellulose solution in NMMO is reduced with increase of the deformation rate, which makes it possible to increase the fiber‐formation velocity within the air zone. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1860–1868, 2001     

Degradation kinetics of acrylonitrile/methyl vinyl ketone copolymers

Methyl vinyl ketone (MVK) was first used to successfully copolymerize with acrylonitrile (AN). This was achieved by using azobisisobutyronitrile as the initiator. Differential scanning calorimetry results of the degradation of AN/MVK copolymers in air are presented. The apparent activation energy of degradation of the copolymers was calculated with Kissinger method. Effects of copolymerization conditions on the apparent activation energy of the copolymers were studied. It has been found that increasing dimethyl sulfoxide concentration in the solvent mixture leads to a rapid increase in the degradation apparent activation energy of AN/MVK copolymers. The apparent activation energy decreases quickly along with increase in the comononer MVK concentration, and this change becomes less prominent as the weight ratio of MVK/AN goes beyond 7/93. The apparent activation energy shows a trend of increase as the copolymerization temperature increases. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1386–1390, 2007     

Rheological study of poly(ethylene glycol)/poly(N‐isopropylacrylamide‐co‐2‐acrylamido‐2‐methylpropanesulphonic acid) semiinterpenetrating network formation

The formation of a series of semiinterpenetrating network (SIPN) hydrogels made by free‐radical copolymerization of N‐isopropylacrylamide (NIPA) and 2‐acrylamido‐2‐methylpropanesulphonic acid (AMPS) with varying comonomer mole ratios, crosslinked with N,N′‐methylene‐bisacrylamide (MBAA) in the presence of poly(ethylene glycol) (PEG) with average molecular weight 6,000 g mol^?1 was studied via determination of complex viscosity, η*, using plate–plate rheometry. The isothermal time dependence of η* at various temperatures or the variation of η* with temperature of pregel solutions was utilized to detect the onset of gelation. The SIPN systems were compared with the corresponding gels made under the same conditions in the absence of PEG. The copolymer mainchain composition has a major effect on the time or temperature for onset of gelation and in particular gelation appears to be inhibited to some extent by MBAA when the AMPS/NIPA mole ratio in the pregel solution exceeds 0.5. The presence or absence of PEG in pregel solutions has a lesser effect on gelation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2083–2087, 2004     

Rheological study of self‐crosslinking and co‐crosslinking of ammonium zirconium carbonate and starch in aqueous solutions

Different from common hydrogel systems formed by a polymer and a crosslinker, a hydrogel consisting of both self‐crosslinkable ammonium zirconium carbonate (AZC) and co‐crosslinkable starch was investigated in this study using rheological measurements. The evolution of viscoelastic properties of AZC solutions and AZC‐starch mixtures was characterized, and the crosslinking kinetics was determined. It was found that for both AZC self‐crosslinking and AZC‐starch co‐crosslinking, the initial bond formation rate and the gel strength exhibited a power law scaling with polymer concentrations. The competition reaction between self‐crosslinking and co‐crosslinking indicates that the gelation kinetics strongly depends on the AZC concentration but less depends on starch concentration. The temperature dependence of crosslinking was described by the Arrhenius plots which demonstrate a good linearity. It was determined that the activation energy of AZC self‐crosslinking was approximately 145–151 kJ/mol, and the activation energy of AZC‐starch co‐crosslinking was 139 kJ/mol. The effect of solution pH on the crosslinking process was also studied. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Determination of kinetics of CO2 absorption in solutions of 2‐amino‐2‐methyl‐1‐propanol using a microfluidic technique

The kinetics for the reactions of carbon dioxide with 2‐amine‐2‐methyl‐1‐propanol (AMP) and carbon dioxide (CO₂) in both aqueous and nonaqueous solutions were measured using a microfluidic method at a temperature range of 298–318 K. The mixtures of AMP‐water and AMP‐ethylene glycol were applied for the working systems. Gas‐liquid bubbly microflows were formed through a microsieve device and used to determine the reaction characteristics by online observation of the volume change of microbubbles at the initial flow stage. In this condition, a mathematical model according to zwitterion mechanism has been developed to predict the reaction kinetics. The predicted kinetics of CO₂ absorption in the AMP aqueous solution verified the reliability of the method by comparing with literatures’ results. Furthermore, the reaction rate parameters for the reaction of CO₂ with AMP in both solutions were determined. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4358–4366, 2015     

Rheological properties of concentrated solutions of high-molecular-weight polyacrylonitrile in dimethyl sulfoxide

The rheological properties of concentrated solutions of polyacrylonitrile in dimethyl sulfoxide are studied in steady and dynamic regimes of shear flow as a function of the molecular–mass characteristics of the polymer. It is found that as the molecular mass of PAN increases, the elastic component of the solution viscosity increases more rapidly than the viscous component; this is one of the main reasons for the instability of the formation and structural nonuniformity of fibers.     

Electrospinning of ethyl–cyanoethyl cellulose/tetrahydrofuran solutions

In this study, electrospinning was used to fabricate ethyl–cyanoethyl cellulose [(E‐CE)C] fiber from a solution of (E‐CE)C/tetrahydrofuran. The diameter of the thinnest fiber fabricated during the electrospinning was about 200 nm. It was found that the diameters of the fibers and their distribution depend on the processing parameters and properties of the solution, such as viscosity, temperature, and concentration, for example. The morphology of the fiber was also observed by SEM. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 242–246, 2004     

Free‐radical copolymerization kinetics of acrylonitrile and methyl acrylate in [BMIM]BF4

The copolymerization of acrylonitrile (AN) and methyl acrylate (MA) was carried out in ionic liquid [BMIM]BF₄ in the presence of azobisisobutyronitrile (AIBN) as an initiator to investigate the polymerization kinetic, including the copolymerization rate, reactivity ratios, and activation energy. The copolymerization rate equation was established according to the effect of initiator and monomer concentrations on the conversion. The copolymerization rate R_p can be noted as , when the copolymerization was in the steady state. The apparent activation energy is 87.94 kJ/mol, while the value of that in the conventional organic solvent (DMF) is ∼ 81 kJ/mol. The reactivity ratios of the investigate system are r_AN = 0.36 and r_MA = 0.68. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4254–4257, 2006     

Rheological characterization of concentrated cellulose solutions in 1‐allyl‐3‐methylimidazolium chloride

The rheological properties of high concentrated wood pulp cellulose 1‐allyl‐3‐methy‐limidazolium Chloride ([Amim]Cl) solutions were investigated by using steady shear and dynamic viscoelastic measurement in a large range of concentrations (10–25 wt %). The measurement reveals that cellulose may slightly degrade at 110°C in [Amim]Cl and the Cox–Merz rule is valid for 10 wt % cellulose solution. All of the cellulose solutions showed a shear thinning behavior over the shear rate at temperature from 80 to 120°C. The zero shear viscosity (η_o) was obtained by using the simplified Cross model to fit experimental data. The η_o values were used for detailed viscosity‐concentration and activation energy analysis. The exponent in the viscosity‐concentration power law was found to be 3.63 at 80°C, which is comparable with cellulose dissolved in other solvents, and to be 5.14 at 120°C. The activation energy of the cellulose solution dropped from 70.41 to 30.54 kJ/mol with an increase of concentration from 10 to 25 wt %. The effects of temperature and concentration on the storage modulus (G′), the loss modulus (G″) and the first normal stress difference (N₁) were also analyzed in this study. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Reaction kinetics of 2‐((2‐aminoethyl) amino) ethanol in aqueous and non‐aqueous solutions using the stopped‐flow technique

Observed pseudo‐first‐order rate constants (k_o) for the reaction between CO₂ and 2‐((2‐aminoethyl) amino) ethanol (AEEA) were measured using the stopped‐flow technique in an aqueous system at 298, 303, 308 and 313 K, and in non‐aqueous systems of methanol and ethanol at 293, 298, 303 and 308 K. Alkanolamine concentrations ranged from 9.93 to 80.29 mol m^?3 for the aqueous system, 29.99–88.3 mol m^?3 for methanol and 44.17–99.28 mol m^?3 for ethanol. Experimentally obtained rate constants were correlated with two mechanisms. For both the aqueous‐ and non‐aqueous‐AEEA systems, the zwitterion mechanism with a fast deprotonation step correlated the data well as assessed by the reported statistical analysis. As expected, the reaction rate of CO₂ in the aqueous‐AEEA system was found to be much faster than in methanol or ethanol. Compared to other promising amines and diamines studied using the stopped‐flow apparatus, the pseudo‐first‐order reaction rate constants were found to obey the following order: PZ (cyclic‐diamine) > EDA (diamine) > AEEA (diamine) > 3‐AP (primary amine) > MEA (primary amine) > EEA (primary amine) > MO (cyclic‐amine). The reaction rate constant of CO₂ in aqueous‐AEEA was double that in aqueous‐MEA, and the difference increased with an increase in concentration. All reaction orders were practically unity. With a higher capacity for carbon dioxide and a higher reaction rate, AEEA could have been a good substitute to MEA if not for its high thermal degradation. AEEA kinetic behaviour is still of interest as a degradation product of MEA. © 2012 Canadian Society for Chemical Engineering     

Viscosity behaviour of acrylonitrile-acrylate copolymer solutions in dimethyl formamide

The viscosities of dimethyl formamide solutions of acrylonitrile-acrylate copolymers were determined at 30,35,40 and 45°C using an Ubbelohde viscometer. The viscosities of homopolymer solutions were also studied. The homopolymers of aerylonitrile and also of methyl, ethyl and butyl acrylates were synthesised in the laboratory. The random copolymers were synthesised by a solution polymerisation technique keeping the acrylonitrile: acrylate ratio as 1:1, 1:2 and 1:3 (w/w). The intrinsic viscosity for each system was computed as a function of temperature. The activation parameters of viscous flow were calculated using the Frenkel-Eyring equation. Voluminosity for all systems was also computed. From intrinsic viscosity and voluminosity data it was concluded that the polymer molecules are spherical in the dimethyl formamide solutions.     

New aspects of viscosity effects on the photopolymerization kinetics of the 2,2‐bis[4‐(2‐hydroxymethacryloxypropoxy)phenyl]propane/triethylene glycol dimethacrylate monomer system

The photopolymerization kinetics and viscosity behavior of 11 2,2‐bis[4‐(2‐hydroxymethacryloxypropoxy)phenyl]propane/triethylene glycol dimethacrylate mixtures were investigated. The viscosity was studied at six temperatures (20–70°C), and the activation energies for the viscosity were determined. The excess logarithm viscosities were calculated and found to be negative over the whole composition and temperature ranges; they were fitted to the Redlish–Kister polynomial equation. The kinetic analysis of the photopolymerization was carried out at three polymerization temperatures (20, 40, and 60°C). The results proved the existence of the most reactive composition (reaching the highest value of the maximum polymerization rate), but the ratio of the monomers in this composition, close to equimolar, showed a tendency to change with the polymerization temperature. The viscosities of the most reactive compositions lay in the range of about 0.1–1.2 Pa s, which was narrow in comparison with the range of viscosities of all the compositions used in the kinetic studies (from 3 × 10^?3 to 1.5 × 10³ Pa s). The activation energies for the polymerization rates were calculated and correlated with the viscosity changes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Electrocopolymerization kinetics of a binary mixture of 3‐chloroaniline 2‐amino‐4‐phenylthiazole and characterization of the obtained block copolymer films

Electrocopolymerization of a binary mixture of 3‐chloroaniline and 2‐amino‐4‐phenylthiazole on platinum electrode in acid medium was carried out under different reaction conditions such as temperature, current density, hydrochloric acid, and monomer concentrations with duration time. The initial rate of the electrocopolymerization reaction on platinum electrode is small and the rate law is R_p = K₂ [D]^1.29[HCl]^0.97[M]^1.94. The apparent activation energy is found to be 38.87 kJ/mol. The obtained copolymer film is characterized by ¹H‐NMR, elemental analysis, GPC IR, UV‐visible, and cyclic voltammetry and compared with those of the two homopolymers. The mechanism of the electrocopolymerization reaction is also discussed and the monomer reactivity ratio (r₁and r₂) is calculated. The thermogravimetric analysis (TGA) is used to confirm the proposed structure and determination of the number of water molecules in the polymeric chain unit. X‐ray and scanning electron microscopic analysis are used to investigate the surface morphology. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2076–2087, 2005     

Cationic photopolymerization of 3‐benzyloxymethyl‐3‐ethyl‐oxetane

The cationic photopolymerization of 3‐benzyloxymethyl‐3‐ethyl‐oxetane (MOX104) initiated by triphenylsulfonium hexafluoroantimonate under UV light was conducted. The kinetics were investigated by real‐time Fourier transform IR spectroscopy and the mechanical and thermal properties of poly(MOX104) were examined by dynamic mechanical analysis and TGA. To adjust the properties of the polymer, different initiator concentrations and comonomer composition were applied. The results showed that the conversion of MOX104 was improved significantly from 17% to almost 90% by adding a certain amount of 3,4‐epoxycyclohexane carboxylate or diglycidyl ether of bisphenol A epoxy resin, while not much effect was observed by adding 1,4‐butanediol diglycidyl ether. Moreover, the glass transition temperature, decomposition temperature and Young's modulus of poly(MOX104) were improved by adding different amounts of diglycidyl ether of bisphenol A epoxy resin. © 2016 Society of Chemical Industry