Diffusion coefficient of DMSO in polyacrylonitrile fiber formation

A H₂O/dimethyl sulfoxide(DMSO) mixture was used as the coagulation bath for the wet‐spun process of acrylonitrile/ammonium itaconate copolymers fibers. Diffusion coefficient of DMSO in the protofibers prepared by acrylonitrile/ammonium itaconate copolymers was determined. It has been found that diffusion coefficient of DMSO outflow of the protofibers prepared by acrylonitrile/ammonium itaconate copolymers synthesized by the solution polymerization is highest compared with those of acrylonitrile/ammonium itaconate copolymers synthesized by H₂O/DMSO mixture suspension polymerization and the aqueous suspension polymerization. With an increase of copolymer concentration in the dope, diffusion coefficient of DMSO decreases continuously. Diffusion coefficient of DMSO increases along with the bath temperature, but the changes of diffusion coefficient values are less prominent as temperature goes beyond 60°C. When DMSO concentration in the coagulation bath was 55 wt %, the value of the diffusion coefficient of DMSO was minimal. Diffusion coefficient of H₂O increases with the jet stretch minus ratio increasing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4447–4451, 2006     

Interaction between polyacrylonitrile and alkalis

Interactions between highly isotactic acrylonitrile homopolymers and alkalis in dimethyl sulfoxide solvent were examined. Coloration occurred as soon as polyacrylonitrile was added to a dimethyl sulfoxide/alkali mixture. The effects of alkali on highly isotactic polyacrylonitrile were greater than those on ordinary polyacrylonitrile. The intrinsic viscosity of polyacrylonitrile decreased quickly with the addition of sodium ethoxide and sodium hydroxide, and the effect of sodium ethoxide was more prominent than that of sodium hydroxide. As the concentration of sodium ethoxide and sodium hydroxide went beyond 0.01 mol/L, the intrinsic viscosity showed a trend of increasing. Within the first half‐hour, there was a great drop in the intrinsic viscosity of highly isotactic polyacrylonitrile, and then the intrinsic viscosity appeared to increase. The intrinsic viscosity of highly isotactic polyacrylonitrile increased continuously with the addition of diethylamine along with time. The effects of alkalis on the tacticity of the polymers followed the order of the alkali strength. Diethylamine was more effective for moderating the stabilization exotherm of polyacrylonitrile than sodium ethoxide and sodium hydroxide. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 272–275, 2006     

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     

Degradation of acrylonitrile–ammonium itaconate copolymers

Acrylonitrile–ammonium itaconate copolymers were prepared by H₂O/dimethyl formamide suspension polymerization technique. Differential scanning calorimetry results of the degradation of acrylonitrile–ammonium itaconate copolymers in air are presented. The apparent activation energy of degradation of the copolymer was calculated using the Kissinger method. Effects of copolymerization conditions on the apparent activation energy of copolymer were studied. Increasing the dimethyl formamide concentration in the solvent mixture leads to a rapid increase in the degradation apparent activation energy of acrylonitrile–ammonium itaconate copolymer. The value of the degradation apparent activation energy of the copolymer synthesized in dimethyl formamide solvent increases up to 168.3 kJ mol^?1. The apparent activation energy decreases quickly along with an increase in ammonium itaconate concentration, and this change becomes less prominent as the weight ratio of ammonium itaconate/acrylonitrile goes beyond 6/94, ΔE_a = 89.4 ± 2.0 kJ mol^?1. The apparent activation energy shows a trend of increase with increasing copolymerization temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1708–1711, 2005     

Solubility of Highly Isotactic Polyacrylonitrile in Dimethyl Sulphoxide

The solubility of highly isotactic acrylonitrile homopolymer into dimethyl sulphoxide (DMSO) was measured. The dissolution of polymer increases drastically at temperature greater than some critical threshold and this process is a thermodynamic equilibrium process. It is shown that the dissolution temperature can be summarized as a function of molecular structural parameters. The dissolution temperature decreases with addition of KCl and NaCl and effect of NaCl is more prominent than KCl. As the concentration of KCl and NaCl increases beyond 0.025 mol/L, the dissolution temperature then increases. There is a decrease in the dissolution temperature of polyacrylonitrile containing sodium ethoxide and sodium hydroxide, and the dissolution temperature increases as the concentration of sodium ethoxide and sodium hydroxide increases beyond 0.01 mol/L. The dissolution temperature of polyacrylonitrile increases continuously with addition of diethylamine. A relationship between the dissolution temperature and the value of isotacticity of polyacrylonitrile was quantitatively obtained.     

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     

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     

Effect of inorganic salts on viscosity of acrylonitrile‐N‐vinylpyrrolidone copolymer solutions

Effects of inorganic salts on viscosities of dimethyl sulphoxide (DMSO) solutions of acrylonitrile(AN)/N‐vinylpyrrolidone(N‐VP) copolymer are discussed. Viscosity was determined by the rotary viscosimeter. It was shown that the solution viscosity decreases quickly with addition of KCl and NaCl and the effect of NaCl is more prominent than that of KCl. As concentration of KCl and NaCl went beyond 0.025 mol/L, the viscosity showed a trend of increase. The viscosity increased considerably with addition of FeCl₃ and CuCl₂. Changes in solution viscosity became less obvious with addition of ZnCl₂. As temperature increased, the viscosity of the copolymer solution containing NaCl decreased most quickly and the copolymer solution consisting of FeCl₃ showed the slowest decrease. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3492–3495, 2003     

Rheological kinetics of acrylonitrile/amino ethyl‐2‐methyl propenoate copolymer solutions in dimethyl sulfoxide

Viscosity behavior of dimethyl sulfoxide solutions of acrylonitrile (AN)/amino ethyl‐2‐methyl propenoate (AEMP) copolymer was discussed. Rheological kinetics of the solutions was studied in contrast. It is shown that the solutions behave the same as Newtonian flow as the rotor speed goes beyond 12 rpm. With an increase of temperature, the apparent viscosity of AN/AEMP copolymer solutions shows a trend of decrease. 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 AN/AEMP 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 as the concentrations of KCl and NaCl up to 0.02 mol L^?1, and then it increases. the apparent flow‐activation energy of AN/AEMP 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. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2972–2976, 2006     

Viscometric Study of Dilute Poly(Acrylonitrile–Ammonium Itaconate) Solutions

The intrinsic viscosity of dilute poly(acrylonitrile–ammonium itaconate) copolymer solution in dimethyl sulfoxide was studied by viscometry. Abnormal phenomena of the η_sp/c versus c curves of poly(acrylonitrile–ammonium itaconate) were found. Owing to the effect of NH₄ ⁺, there were three anomalistic turning points in the curve of the Huggins dependence compared with other polyacrylonitrile copolymers.     

Rheological behavior of N,N‐dimethyl acrylamide–acrylamido methylpropane sulphonate copolymer

Copolymer of N,N‐dimethylacrylamide (NNDAM) and sodium 2‐acrylamido‐2‐methylpropanesulfonate (NaAMPS) have been prepared by free‐radical copolymerization and characterized with the help of molecular weight, molecular weight distribution, intrinsic viscosity, and monomer ratio in the copolymer. The solution behavior of a copolymer containing 26.62 wt % NaAMPS is studied in different solvents, namely, water (W), dimethyl sulfoxide (DMSO), ethylene glycol (EG), and ethanol (EtOH). The reduced viscosity of the copolymer is highly dependent on the ionic strength of the copolymer solution. The reduced viscosity decreases as a function of solvent selection in the order W > DMSO > EtOH > EG. The shapes of the η_sp / C vs. C plots indicate the polyelectrolyte behavior of the copolymer, except for the case of EG solutions, where nonpolyelectrolyte behavior is observed. However, at a certain degree of ionization attained by adding W as cosolvent, the copolymer begins to demonstrate polyelectrolyte behavior. For this copolymer, there exists a minimum concentration of brine (NaCl, CaCl₂, etc.) above which solution viscosity is not further reduced. The copolymer solution behaves as a power law fluid, and exhibits time‐dependent thixotropic behavior. The copolymer cannot regain its solution viscosity when allowed to shear at a constant rate for long period of time. The reduced viscosities of copolymer solutions increase with increasing temperature in W and DMSO, yet decreases with increasing temperature in EG. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1521–1529, 2002     

无机盐对丙烯腈与N-乙烯基吡咯烷酮共聚物溶液黏度的影响

引　言黏度是碳纤维前驱体聚丙烯腈原丝纺丝工艺过程中重要的控制指标之一 .为得到高性能的原丝 ,一般采用提高共聚物的分子量、增加纺丝原液中共聚物的浓度或改变共聚单体等方法 ,结果使得纺丝原液黏度急剧上升 ,纺丝压力过大 ,不便于输送 ,易出现危险 .增加共聚单体的含量可降低原液黏度 ,但共聚单体的含量也有极限值[1,2 ] .少量文献曾提到过无机盐对聚丙烯腈溶液黏度是有影响的[3 ,4] ,指出某些无机盐的加入可使得丙烯腈共聚物溶液黏度下降[5] ,这对于原丝生产具有重要意义 ,但对于原液中常出现的离子Na 、Zn2 、Fe3 、Cu2 、K 、…     

Degradation kinetics of acrylonitrile/ammonium acrylate copolymers

acrylonitrile (AN)/ammonium acrylate (AAT) copolymers were prepared by H₂O/dimethyl formamide suspension polymerization technique. Differential scanning calorimetry results of the degradation of AN/AAT copolymers in air are presented. The apparent activation energy of degradation of the copolymer was calculated by using Kissinger method. Effects of copolymerization conditions on the apparent activation energy of copolymer were studied. It has been found that increasing dimethyl formamide concentration in the solvent mixture leads to a rapid increase in the degradation apparent activation energy of AN/AAT copolymer. The value of the degradation apparent activation energy of the copolymer synthesized in dimethyl formamide solvent increases up to 141.7 kJ mol^?1. The apparent activation energy decreases quickly, along with increase in AAT concentration, and this change becomes less prominent as the weight ratio of AAT/AN goes beyond 6/94. The apparent activation energy shows a trend of increase with increasing copolymerization temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4649–4653, 2006     

Monomer apparent reactivity ratios for acrylonitrile/ammonium itaconate radical copolymerization systems

Ammonium itaconate was first used to copolymerize with acrylonitrile. This was achieved by using azobisisobutyronitrile as the initiator and dimethyl sulfoxide as the solvent. Effects of copolymerization systems on monomer apparent reactivity ratios for acrylonitrile/ammonium itaconate copolymers were studied. The values of monomer apparent reactivity ratios were calculated by Kelen‐Tudos method. The apparent reactivity ratios in the aqueous suspension polymerization system are similar to those in the solution polymerization system at polymerization conversions of less than 18% [reactivity ratio of acrylonitrile (r_AN) = 0.47 ± 0.01, reactivity ratio of ammonium itaconate (r_AIA) = 3.08 ± 0.01]. At conversions of more than 50%, the changes of monomer apparent reactivity ratios become less prominent (r_AN = 0.68 ± 0.01, r_AIA = 2.47 ± 0.01). In water‐rich reaction medium [(H₂O/dimethylsulfoxide (DMSO) > 80/20)], the monomer apparent reactivity ratios are approximately equivalent to those in the aqueous suspension polymerization system. In DMSO‐rich reaction medium (DMSO/H₂O > 80/20), the apparent reactivity ratios are similar to those in the solution polymerization system. With an increase in the polarity of the solvent, the values of apparent reaction ratios both decrease. The values of apparent reaction ratios gradually tend to 1 with increasing the copolymerization temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3920–3923, 2007     

Poly(sulfobetaine)s and corresponding cationic polymers. X. Viscous properties of zwitterionic poly(sulfobetaine) derived from styrene–(N,N‐dimethylaminopropyl maleamidic acid) copolymer in aqueous salt solutions

A styrene–[N,N‐dimethyl (maleamidic acid) propyl ammonium propane sulfonate] (SDMMAAPS) copolymer was synthesized through an amidoacidation reaction of styrene–maleic anhydride (SMA) alternating copolymer with N,N‐dimethylaminopropylamine (ring‐opening reaction), which was then reacted with propane sultone. The effect of various salt solutions on the intrinsic viscosity of this ampholytic ADMMAAPS copolymer was investigated. The results showed that the effect of counter ions on the intrinsic viscosity of SDMMAAPS was not entirely similar to that of other zwitterionic poly(sulfobetaine)s. The greatest difference from other poly(sulfobetaine)s is the carboxylic group on the polymer chain unit of SDMMAAPS. The Huggins constants for SDMMAAPS in aqueous salt solutions, however, were also quite different from those of other sulfobetaine copolymers, such as styrene–N,N‐dimethyl (maleimido propyl) ammonium propane sulfonate] (SDMMAPS) copolymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 726–734, 2004     

Properties of (BA)n-B type block copolymers of butadiene and dimethyl itaconate prepared using macroazonitrile initiators

Multi-block copolymers of the (BA)_n-B type, where A is poly(dimethyl itaconate) and B is polybutadiene, were synthesised using a macroazonitrile initiator. This was prepared by the reaction of 4, 4′ azobis (4-cyanopentanoyl chloride) with hydroxyl terminated polybutadienes. and subsequent decomposition of the azo group in the presence of dimethyl itaconate monomer yielded the block copolymer. Measurement of their glass transition temperatures revealed that the copolymers formed two phases. The dynamic thermomechanical properties were measured and this demonstrated that in the temperature range 290–400K, the glassy poly(dimethyl itaconate) blocks acted as crosslinking sites for the elastomeric polybutadiene blocks and that the materials behaved like typical elastoplastic block copolymers. Property variation was obtained when the ratio of polybutadiene to poly(dimethyl itaconate) in the copolymers was altered.     

Charge transfer copolymerization and properties of isopropyl methacrylate with acrylonitrile and methacrylonitrile

Isopropyl methacrylate (IPMA) with Acrylonitrile (AN) and Methacrylonitrile (MAN) copolymers of different copositions were prepared at 60°C and 80°C, respectively, using a mixture of n-Butylamine (nBA) and carbon tetrachloride (CCl₄) in dimethyl sulphoxide (DMSO) as a charge transfer (CT) initiator. The percentage composition of the copolymers was established by elemental analysis. The copolymerization reactivity ratios were computed by the Kelen–Tudos method. In both the systems, IPMA was found to be more reactive; the copolymers sequence was random in nature. The copolymers were characterized by IR, ¹H-NMR, ¹³C-NMR spectroscopy and intrinsic viscosity measurements in dimethyl formamide (DMF) at 30±0.1°C. The thermal behavior of the AN-IPMA copolymers was studied by thermogravimetry (TG) in air. The thermal stability increased, with increasing AN content in the copolymer chain. The solubility parameter of AN-IPMA copolymer was evaluated by studying the intrinsic viscosity in different solvents. The solubility parameter of the copolymer was found to be 9.7 (cal/cc)^1/2.     

Determination of the degradation apparent activation energy of acrylonitrile/acrylic acid copolymers

Acrylonitrile/acrylic acid copolymers were prepared by H₂O/dimethyl formamide suspension polymerization technique. Differential scanning calorimetry was used to investigate the degradation of acrylonitrile/acrylic acid copolymers in air. The apparent activation energy of degradation of the copolymer was calculated with the Kissinger method. Effects of copolymerization conditions on the apparent activation energy of copolymer were studied. It has been found that increasing the dimethyl formamide concentration in the solvent mixture led to a gradual increase (97.3–149.4 kJ mol^?1) in the apparent activation energy of degradation of the acrylonitrile/acrylic acid copolymers. The apparent activation energy decreases with increase in acrylic acid concentration, and this change became less prominent as the acrylic acid/acrylonitrile weight ratio is more than 5/95. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4668–4671, 2006     

Diffusion coefficient of DMF in acrylic fiber formation

A H₂O/dimethyl formamide (DMF) mixture was used as the coagulation bath of wet‐spun process for acrylic fibers. Diffusion coefficient of DMF in the protofibers prepared by acrylonitrile/acrylamide copolymers was determined. It has been found that diffusion coefficient of DMF outflow of the protofibers prepared by acrylonitrile/acrylamide copolymers synthesized by solution polymerization is highest compared with those of acrylonitrile/acrylamide copolymers synthesized by H₂O/DMF mixture suspension polymerization and aqueous suspension polymerization. With an increase of copolymer concentration in the dope, diffusion coefficient of DMF decreases continuously. Diffusion coefficient of DMF increases along with the bath temperature, but the changes in diffusion coefficient values are less prominent as temperature goes beyond 55°C. When DMF concentration in the coagulation bath was 50%, the value of the diffusion coefficient of DMF was minimal. Diffusion coefficient of DMF increases along with jet stretch minus ratio increase. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3616–3619, 2006     

Self‐assembled acrylamide‐based copolymer/surfactant with high‐temperature resistance for enhanced oil recovery

In this article, we report on a water‐soluble self‐assembled system that consisted of an acrylamide (AM)‐based copolymer and a nonionic surfactant for enhancing oil recovery. The copolymer, denoted as poly(acrylamide–acrylic acid–diallyl dimethyl ammonium chloride–N ‐allyl benzamide) (PMADN), was synthesized with AM, acrylic acid, diallyl dimethyl ammonium chloride, and N ‐allyl benzamide, and the nonionic surfactant was Tween 40. The results of our investigation of the ratio of the copolymer to Tween 40 show that the optimal concentrations of PMADN and Tween 40 were 1000 and 500 mg/L, respectively. When it was heated to 115–120 °C for 15 min, the apparent viscosity of the self‐assembly system increased 19.2%, and its viscosity retention rate remained at 11.6% under 1000 s^?1. When the system was dissolved in 12,000 mg/L NaCl, 2000 mg/L CaCl₂, and 2000 mg/L MgCl₂ solutions, the viscosity retention rates were 22.3%, 12.1%, and 17.6%, respectively. In addition, a 2000 mg/L PMADN–Tween 40 solution dramatically enhanced the oil recovery up to 13.4%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45202.