Values Of Reactivity Ratios Research Articles

Synthesis and characterization of copolymer of styrene with methacrylic acid initiated by triphenylbismuthonium 1,2,3,4‐ tetraphenylcyclopentadienylide

AbstractThe radical copolymerization of styrene with methacrylic acid (MAA) initiated by triphenylbismuthonium 1,2,3,4‐tetraphenylcyclopentadienylide in dioxan at 80 ± 0.1 °C for 3 h results in the formation of alternating copolymer as evidenced from the values of reactivity ratios as r1 (styrene) = 0.03 and r2 (MAA) = 0.025. The kinetic expression is Rp α [I]0.5 [Sty] [MAA] and overall energy of activation is computed to be 23 kJ/mol. The FTIR spectrum of the copolymer shows the presence of bands at 3054 cm−1 assigned to the phenyl group of styrene and at 1724 cm−1 assigned to the COOH group of MAA. The 1H‐NMR spectrum of the copolymer shows peaks between 7.20 and 7.27 δ assigned to the phenyl protons of styrene and at 12.5 δ assigned to the COOH proton of MAA. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1838–1843, 2005

2D NMR studies of acrylonitrile–methyl acrylate copolymers

The microstructure of acrylonitrile–methyl acrylate copolymers prepared by the solution polymerization using 2,2′-azobisisobutyronitrile (AIBN) as free radical initiator was investigated by two-dimensional NMR techniques. 2D-heteronuclear single quantum correlation (HSQC) and the total correlation spectroscopy (TOCSY) have been utilized to resolve the complex 1H NMR spectrum and to establish the compositional and configurational sequences of acrylonitrile–methyl acrylate copolymers. 2D HSQC and TOCSY showed compositional and configurational sensitivity of methine protons of A and M units upto the triad level. Heteronuclear multiple-bond correlation (HMBC) spectroscopy has been used to study carbon (carbonyl/nitrile)–proton coupling. The carbonyl and nitrile carbons showed compositional sensitivity upto the triad level. The values of reactivity ratios were determined by Kelen–Tudos (KT) and non-linear error in variable method (RREVM).

Non-uniqueness of penultimate model reactivity ratios and treatment of kinetic data

Non-linear curve-fitting regression method using parametric equation as ‘user model’ has been utilized to determine reactivity ratios signifying effects of terminal and penultimate groups in copolymerization. Residuals, standard errors and correlation coefficients have been compared with those of terminal model using Fukuda's data on styrene–methyl methacrylate copolymerization. Non-uniqueness and occurrence of two sets of values for the penultimate model reactivity ratios have been explained on the basis of specified feed composition calculations. The two sets of reactivity ratios corresponding to explicit penultimate model have been used for treatment of kinetic data and consistent and acceptable values of various kinetic constants have been obtained with only one set. The value of ϕ obtained corresponds very closely to theoretically predicted value.

Synthesis and microstructural characterisation of copolymers ofL‐lactide and trimethylene carbonate prepared using the SmI2/Sm initiator system

AbstractPolymerisation of trimethylene carbonate (TMC) and its copolymerisation withL‐lactide (LA) using the SmI2/Sm initiator system is reported. The reactions were carried out at different temperatures to optimize the reaction conditions. Reactivity ratio values evaluated using the Kelen–Tüdos method were 7.24 and 0.25 for LA and TMC, respectively. Microstructure of the copolymers and its change with the reaction time is reported using 1D (1H and13C) and 2D heteronuclear multiple‐bond correlation NMR spectroscopic techniques. Electrospinning of the resulting copolymers was tried for the generation of fibres. Drastic deviations of the thermodynamic state from equilibrium were seen in the first heating cycle of the DSC trace of the electrospun fibres and are also reported here. Copyright © 2005 Society of Chemical Industry

Styrene/Methacrylic Acid Monomer Reactivity Ratio Estimation in Bulk and Solution at High Temperatures

: Styrene/methacrylic acid (Sty/MAA) free radical copolymerizations have been conducted in bulk and in m-xylene solution (60 wt% solvent level) at 100 and 130°C using tert-butyl peroxybenzoate as initiator. Monomer reactivity ratios and their temperature dependence have been determined from low conversion copolymer composition data using the computer software package RREVM, which is based on the error in variables model (EVM) method. It was found that the reactivity ratio values change with dilution by m-xylene from the values obtained in bulk at both temperatures.

Radical copolymerization studies of an amphiphilic macromonomer derived from Triton X-100. Reactivity ratios determination by in situ quantitative 1H NMR monitoring

This article deals with the estimation of the reactivity of a novel methacrylic macromonomer with amphiphilic character derived from Triton X-100 (MT) in radical copolymerisation reaction with acrylic acid (AA). Two approaches to estimate the reactivity ratio of the macromonomer are described. The first involves the use of the Jaacks equation valid for systems with a large excess of one of the comonomers and leads to r AA=0.31. The second method uses a low molecular weight model monomer (MTm) that reproduces the chemical structure of the macromonomer. A non-linear fitting of the experimental data of the system MTm–AA to an integrated form of the copolymerisation equation which describes the terminal model postulated by Mayo and Lewis, gave reactivity ratio values of r MTm=2.5 and r AA=0.30. The results obtained from the two estimations suggest that methacrylic double bond reactivity is not affected by poly(oxyethylene oxide) chain length. In situ quantitative 1H NMR analysis was used to monitor monomer consumption and therefore to follow the course of the copolymerisation reaction in both approaches.

Determination of monomer apparent reactivity ratios for acrylonitrile-acrylamide copolymerization system

Effect of copolymerization systems on monomer apparent reactivity ratios for copolymer of acrylonitrile with acrylamide was studied for contrast. Values of monomer apparent reactivity ratios were calculated by Kelen-Tudos method. It has been found that the apparent reactivity ratios in aqueous suspension polymerization system were similar to those in solution polymerization system at polymerization conversion less than 18% [reactivity ratio of acrylonitrile (rAN) = 0.398± 0.004, reactivity ratio of acrylamide (rAM) = 2.61± 0.02]. As conversion of more than 60%, the changes of monomer apparent reactivity ratios become less prominent (rAN = 0.651± 0.008, rAM = 1.98± 0.01). In water-rich reaction medium [(H2O/dimethylsulfoxide (DMSO) > 80/20), monomer apparent reactivity ratios were approximately equivalent to those in aqueous suspension polymerization system. In DMSO-rich reaction medium (DMSO/H2O > 80/20), apparent reactivity ratios were similar to those in solution polymerization system. With an increase of polarity of solvent, values of apparent reaction ratios both decreased. The values of apparent reaction ratios gradually tend to 1 with increasing the copolymerization temperature.

Influence of aggregate formation in the copolymerization of ethyl α-hydroxymethylacrylate with methyl methacrylate

Ethyl α-hydroxymethylacrylate was homopolymerized and copolymerized with methyl methacrylate in chlorobenzene and 1,4-dioxane solutions at 50 °C with 1.5 × 10−2 mol/L 2,2′-azobisisobutyronitrile as an initiator and a global monomer concentration of 3.0 mol/L. The experiments showed differences in the calculated values of the monomer reactivity ratios in both solvents. The kinetic behavior was analyzed in terms of the implicit penultimate effect and the radical reactivity ratios. All the parameters were examined with respect to the aggregation ability of the ethyl α-hydroxymethylacrylate monomer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4187–4195, 2005

Kinetics of copolymerization of acrylonitrile with ammonium itaconate in a H2O/dimethyl formamide mixture

AbstractKinetics of copolymerization of acrylonitrile (AN) with ammonium itaconate (AI) initiated by azobisisobutyronitrile (AIBN) were investigated in a H2O/dimethyl formamide (DMF) mixture between 50 and 70°C under a N2 atmosphere. The rate of copolymerization and particle size were measured. The kinetic equation of copolymerization system is obtained and the overall activation energy for the copolymerization system was computed. Values of monomer apparent reactivity ratios were calculated by the Kelen–Tudos method. It was found that in DMF‐rich reaction medium (DMF/H2O > 80/20), monomer apparent reactivity ratios are similar to those in the solution polymerization system. Effect of hydroquinone and dioxane additives on copolymerization was discussed. The polymerization is retarded by hydroquinone and accelerated by dioxane, which confirms the free‐radical copolymerization of AN with AI. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1151–1155, 2004

High temperature copolymerization of styrene/ethyl acrylate: Reactivity ratio estimation in bulk and solution

AbstractStyrene/ethyl acrylate (Sty/EA) free‐radical copolymerizations have been conducted in bulk with and without initiator and in solution using p‐xylene and m‐xylene (30 wt% and 60 wt% solvent level) at 100°C and 130°C. The monomer reactivity ratio values and their temperature dependence have been determined from low conversion copolymer composition data using the computer software package RREVM, which is based on the error in variables model (EVM) method. Copolymer composition data at low conversion confirmed the Mayo–Lewis model at both temperatures. The reactivity ratio values of the Sty/EA system do not seem to change with dilution by nonpolar solvents at low concentration from the reactivity ratio values obtained in bulk with and without initiator. However, xylene isomers were found to have a slight effect on the reactivity ratio value of ethyl acrylate when high solvent concentration was utilized. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 186–195, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20009

Synthesis and characterization of copolymers of limonene with styrene initiated by azobisisobutyronitrile

The radical copolymerization of limonene with styrene by azobisisobutyronitrile in xylene at 80 ± 0.1 °C for 2 h, under inert atmosphere of N 2, yields alternating copolymers. The kinetic expression is R p∝[I] 0.5[Sty] 1.0[Lim] −1.0. The overall activation energy is calculated as 41 kJ/mol. The FTIR and 1H-NMR spectra of copolymers show bands at 3000 and 1715 cm −1 and peaks at 6.8 δ and 5.3 δ due to phenyl protons of styrene and trisubstituted olefinic protons of limonene, respectively. The values of reactivity ratios r 1(Sty)=0.0625 and r 2(Lim)=0.014, calculated by Kelen–Tüdos method. The Alfrey–Price Q– e parameters for limonene are 0.438 and −0.748, respectively. The penultimate unit effect is favoured in the present system and the value of φ is 38.49.

Estimation of monomer reactivity ratios in free‐radical solution copolymerization of lauryl methacrylate–isobutyl methacrylate

AbstractCopolymers of isobutyl methacrylate (i‐BMA) and lauryl methacrylate (LMA) were prepared by free‐radical solution copolymerizations at 70 °C with azobisisobutyronitrile (AIBN) as an initiator. The synthesis of these copolymers was investigated over a wide composition range both at low and high conversion levels. Copolymer compositions were determined from the %C, %H, and %O contents of copolymer by elemental analysis. Monomer reactivity ratios were estimated by analyzing composition data with nonlinear least‐squares (NLLS) models based on Marquardt optimization and van Herk methods. The point estimates, 95% individual confidence intervals and 95% joint confidence intervals are obtained from differential and integral approaches. Even though no explicit integral form for penultimate unit model (PUM) is available, a numerical approach is developed for integral estimation of reactivity ratios from PUM. A simulator program was developed which upon coupling of experimental data, NLLS analysis, and D‐optimal criteria calculates the best optimized values of monomer reactivity ratios and monomer feed compositions in a sequential and iterative order for terminal and penultimate unit models. Moreover, the simulator has the capibilities to calculate all features of van Herk method, maximum compositional drift in each monomer feed composition, and data reconciliation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 112–129, 2004

Monomer reactivity ratios and glass‐transition temperatures of copolymers based on dimethyl amino ethyl methacrylate and two structural hydroxy‐functional acrylate isomers

AbstractTwo chemical structural isomers, 2‐hydroxyethyl methacrylate and ethyl α‐hydroxymethyl acrylate, were copolymerized with dimethyl amino ethyl methacrylate in bulk at 50 °C with 1.0 × 10−2 mol/L 2,2′‐azobisisobutyronitrile as an initiator. Experiments showed differences in the values of the monomer reactivity ratios due to electronic or steric contributions to the cross‐propagation reaction. The homopolymer glass‐transition temperature (Tg), along with the intramolecular and intermolecular structure and Johnston's equation, enabled a description of the experimental variations of the copolymer Tg. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2659–2666, 2003

Determination of the reactivity ratios for acrylonitrile/N‐vinylpyrrolidone copolymerization systems

AbstractThe effects of the copolymerization system on the monomer reactivity ratios for a copolymer of acrylonitrile with N‐vinylpyrrolidone was studied for contrast. The values of the monomer reactivity ratios were calculated by the Kelen–Tudos method. The reactivity ratios in the aqueous suspension polymerization system were similar to those in the solution polymerization system at polymerization conversions of less than 6% [reactivity ratio of acrylonitrile (rAN) = 0.438 ± 0.015, reactivity ratio of N‐vinylpyrrolidone (rN‐VP) = 2.28 ± 0.02]. As conversion of more than 12%, the changes in the monomer reactivity ratios became less prominent (rAN = 0.651, rN‐VP = 1.98). In the water‐rich reaction medium [H2O/dimethylsulfoxide (DMSO) > 60/40], the monomer reactivity ratios were approximately equivalent to those in the aqueous suspension polymerization system. In the DMSO‐rich reaction medium (DMSO/H2O > 60/40), the reactivity ratios were similar to those in the solution polymerization system. With an increase in the polarity of the solvent, the values of the reaction ratios both decreased. The values of the reaction ratios gradually tended toward 1 with increasing copolymerization temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 422–425, 2003

Multicenter nature of titanium‐based Ziegler–Natta catalysts: Comparison of ethylene and propylene polymerization reactions

AbstractThis article discusses the similarities and differences between active centers in propylene and ethylene polymerization reactions over the same Ti‐based catalysts. These correlations were examined by comparing the polymerization kinetics of both monomers over two different Ti‐based catalyst systems, δ‐TiCl3‐AlEt3 and TiCl4/DBP/MgCl2‐AlEt3/PhSi(OEt)3, by comparing the molecular weight distributions of respective polymers, in consecutive ethylene/propylene and propylene/ethylene homopolymerization reactions, and by examining the IR spectra of “impact‐resistant” polypropylene (a mixture of isotactic polypropylene and an ethylene/propylene copolymer). The results of these experiments indicated that Ti‐based catalysts contain two families of active centers. The centers of the first family, which are relatively unstable kinetically, are capable of polymerizing and copolymerizing all olefins. This family includes from four to six populations of centers that differ in their stereospecificity, average molecular weights of polymer molecules they produce, and in the values of reactivity ratios in olefin copolymerization reactions. The centers of the second family (two populations of centers) efficiently polymerize only ethylene. They do not homopolymerize α‐olefins and, if used in ethylene/α‐olefin copolymerization reactions, incorporate α‐olefin molecules very poorly. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1745–1758, 2003

Copolymerization of α‐terpineol with styrene: Synthesis and characterization

AbstractRadical copolymerization of α‐terpineol with styrene (Sty) initiated by azobisisobutyronitrile in xylene at 80 ± 0.1 °C for 2 h followed ideal kinetics and resulted in the formation of a functional and alternating copolymer as evidenced by spectral analysis. The activation energy was 28 kJ/mol. α‐Terpineol underwent copolymerization as well as a chain‐transfer reaction. The values of the monomer reactivity ratios calculated by the Kelen–Tüdos method were r1 (Sty) = 0.033 and r2 (α‐terpineol) = 0.004. The Alfrey–Price Q‐e parameters for α‐terpineol were calculated as 0.104 and 3.052, respectively. The mechanism of copolymerization is elucidated, and it is concluded that the double bond present in the monocyclic ring of α‐terpineol is an active site for copolymerization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1700–1707, 2003

Kinetics and Mechanism of Copolymerization of Linalool with Acrylonitrile

Linalool (LIN) and acrylonitrile (AN) were copolymerized by benzoyl peroxide (BPO) in xylene at 75°C for 60 min. The system follows ideal kinetics with bimolecular termination and results in the formation of an alternating copolymer as evidenced from the values of reactivity ratios as r1(AN)=0.011 and r2(LIN)=0.017. The overall activation energy is 35.2 kJ/mol. The FTIR spectrum of the copolymer shows the presence of the band at 3467 cm−1 due to hydroxy group of LIN and at 2240 cm−1 due to a cyanide group of AN. The 1H-NMR spectrum shows peaks at 7.0–7.7 δ due to alcoholic group of LIN. 13C-NMR spectrum of copolymer has peaks at δ ppm=116–120 of –CN, and δ ppm=75–77 of –C–OH. The TGA and DSC studies show that the copolymer is highly stable thermally and has glass transition temperature (Tg)=50°C. The mechanism of copolymerization has been elucidated. This paper also reports the measurement of Mark Houwink constants in THF at 25°C by means of GPC as α=0.50 and K=2.24×10−3 dl/g.

Mechanistic and kinetic studies of the copolymerization of citronellol and acrylonitrile initiated by benzoylperoxide

The radical copolymerization of citronellol with acrylonitrile (AN) in xylene at 75 ± 0.1°C for 1 h in the presence of benzoylperoxide (BPO) follows ideal kinetics with bimolecular termination and results in the formation of an alternating copolymer as evidenced from the values of reactivity ratios as r 1 (acrylonitrile) = 0.0062 and r 2 (citronellol) = 0.0003, which have been calculated using the Kelen–Tüdos method. The overall activation energy is computed as 30 kJ/mol. The IR spectrum of the copolymer shows the presence of brands at 3500 cm-1, assigned to the alcoholic group, and 2240 cm-1, assigned to the cyanide group. The 1H-NMR spectrum of the copolymer shows peaks between 7 and 7.7 δ, assigned to the alcoholic group of citronellol. The nitrogen percentage was evaluated by elemental analysis. The Alfrey–Price Q–e parameters for citronellol has been calculated as -0.46 and 0.97. The copolymer is highly thermally stable and has a glass transition temperature (T g) of 102°C, as evaluated by Differential Scanning Calorimetry (DSC) studies. The mechanism has also been elucidated.

Synthesis and characterization of optically active and functional terpolymer of citronellol, styrene, and methyl methacrylate: A kinetic study

AbstractSynthesis of a series of novel terpolymers, consisting of two electron‐donating monomers, viz. citronellol (optically active) and styrene, with one electron‐accepting monomer, i.e. methyl methacrylate, using benzoyl peroxide as radical initiator and xylene as diluent at 80°C for 2 h has been extensively studied. The system follows ideal kinetics with an overall activation energy of 33 kJ mol−1. The formation of the terpolymer is confirmed by the presence of peaks at 7–8 δ because of phenyl group, 3.4–4 δ because of methoxy group, and 7–7.7 δ because of alcoholic group in 1H NMR spectrum of the terpolymer. Further, the bands at 2900 cm−1, 1750 cm−1, and 3400 cm−1, observed in FTIR spectrum of terpolymer, evidence the presence of phenyl, methoxy, and alcoholic group respectively. The monomer feed–terpolymer composition was determined by the Kelen–Tudos method. The values of reactivity ratios are r1(MMA) = 0.9 and r2(styrene + citronellol) = 0.02. © 2002 John Wiley & Sons, Inc. Adv Polym Techn 21: 59–64, 2002; DOI 10.1002/adv.10009

Kinetics and Mechanism of Copolymerization of α-terpineol with Methylmethacrylate in Presence of Azobisisobutyronitrile as an Initiator

The radical copolymerization of α-terpineol with methyl-methacrylate in xylene at 80±0.1 ○C for 50 minutes in the presence of azobisisobutyronitrile (AIBN) follows ideal kinetics and results in the formation of a functional and random copolymer. The activation energy is 33 KJ/mole. The IR spectrum and NMR spectra of the copolymer(s) shows the bands at 1750 and 3400 cm−1 for ester group of methylmethacrylate and alcoholic group of α-terpineol and peaks at 3 to 4δ for methoxy group and at 6.5 to 7.5δ due to alcoholic group of methylmethacrylate and α-terpineol repectively. The values of reactivity ratios, calculated by Kelen–Tudos method, are r1 (MMA) = 0.18 and r2 (α-terpineol) = 0.046. The Alfrey-Price; Q–e parameters for α-terpineol has been calculated as 0.149 and 2.486. The mechanism of copolymerization has been elucidated and it is concluded that the double bond present in the monocyclic ring of α-terpineol is an active site for copolymerization and the alcoholic group of α-terpineol remain to give functional copolymer.