Kinetics and Modelling of Bulk and Solution Diallyl Terephthalate Polymerization

2006 ◽  
Vol 4 (1) ◽  
Author(s):  
Iztok Hace
Keyword(s):  
Kinetic Model ◽  
Kinetic Parameters ◽  
Rate Constants ◽  
Chain Transfer ◽  
Average Molecular Weight ◽  
Propagation Rate ◽  
Reaction Conditions ◽  
Diffusion Limitations ◽  
Kinetics Of ◽  
Dicyclohexyl Peroxydicarbonate

Free radical polymerization kinetics of diallyl terephthalate (DAT) in solution was investigated with two different peroxide initiators: dicyclohexyl peroxydicarbonate (CHPC) and benzoyl peroxide (BPO) in temperature range from 50°C to 110°C, where ortho-xylene was used as a solvent. Conversion points were measured using Fourier Transform Infrared (FTIR) measurements. Previously developed kinetic model for bulk DAT polymerization, was extended to solution DAT polymerization. The ratio of solvent chain - transfer rate constants to propagation rate constants of the polymerization system were found between 1.25 10-4 to 1.68 10-4 for various reaction conditions. They were obtained using the calculated initial polymerization rates and the number average molecular weight measurements made by GPC. The effect of different solvent fractions and initiator concentrations on the diffusion limitations were investigated. Only two kinetic parameters, kpd0 and ktd0 were obtained by fitting the kinetic model onto measured conversions for various reaction conditions at 0.2, 0.5 and 0.8 solvent fractions. Thus obtained kpd0 and ktd0 kinetic parameters were extrapolated to zero solvent fractions and from obtained values of kinetic parameters the conversion points for bulk DAT polymerization were calculated and compared to measured conversion points.

Synthesis of highly reactive polyisobutylene by catalytic chain transfer in hexanes at elevated temperatures; determination of the kinetic parameters

2017 ◽  
Vol 8 (18) ◽  
pp. 2852-2859 ◽  
Author(s):  
Tota Rajasekhar ◽  
Jack Emert ◽  
Rudolf Faust
Keyword(s):  
Kinetic Parameters ◽  
Rate Constants ◽  
Chain Transfer ◽  
Elevated Temperatures ◽  
Polymerization Rate ◽  
Carbenium Ions ◽  
Catalytic Chain Transfer ◽  
Highly Reactive Polyisobutylene ◽  
Increasing Temperature

The rate constants of activation/deactivation for dormant oxonium/active carbenium ions have been measured and related to the increasing polymerization rate with increasing temperature.

scholarly journals Extended Rate Constants Distribution (RCD) Model for Sorption in Heterogeneous Systems: 2. Importance of Diffusion Limitations for Sorption Kinetics on Cryogels in Batch

Gels ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 15 ◽  
Author(s):  
Irina Malakhova ◽  
Alexey Golikov ◽  
Yuliya Azarova ◽  
Svetlana Bratskaya
Keyword(s):  
Kinetic Parameters ◽  
Diffusion Model ◽  
Residence Time ◽  
Rate Constants ◽  
Heterogeneous Systems ◽  
Sorption Kinetics ◽  
Sorption Rate ◽  
Kinetic Curves ◽  
Dynamic Conditions ◽  
Diffusion Limitations

Here we address the problem of what we can expect from investigations of sorption kinetics on cryogel beads in batch. Does macroporosity of beads indeed help eliminate diffusion limitations under static sorption conditions? Are sorption rate constants calculated using phenomenological kinetic models helpful for predicting sorption properties under dynamic conditions? Applying the rate constants distribution (RCD) model to kinetic curves of Cu(II) ions sorption on polyethyleneimine (PEI) cryogel and gel beads and fines, we have shown that diffusion limitations in highly swollen beads are very important and result in at least ten-fold underestimation of the sorption rate constants. To account for intraparticle diffusion, we have developed the RCD-diffusion model, which yields “intrinsic” kinetic parameters for the sorbents, even if diffusion limitations were important in kinetic experiments. We have shown that introduction of a new variable—characteristic diffusion time—to the RCD model significantly improved the reliability of sorption kinetic parameters and allowed prediction of the minimal residence time in column required for efficient uptake of the adsorbate under dynamic conditions. The minimal residence time determined from kinetic curves simulated using the RCD-diffusion model was in good agreement with experimental data on breakthrough curves of Cu(II) ion sorption on monolith PEI cryogel at different flow rates.

scholarly journals ACETONE HYDRATION KINETICS AND EVALUATION OF INPUT OF 2-PROPANOL DEHYDRATION REACTION ON RANEY NICKEL UNDER HYDROGENATION CONDITIONS

2018 ◽  
Vol 59 (1) ◽  
pp. 14
Author(s):  
Yu.E. Romanenko ◽  
A.A. Merkin ◽  
O.V. Lefedova
Keyword(s):  
Aqueous Solution ◽  
Kinetic Model ◽  
Raney Nickel ◽  
Rate Constants ◽  
Dehydration Reaction ◽  
Hydrogenation Rate ◽  
Hydration Kinetics ◽  
Skeletal Nickel ◽  
Kinetics Of ◽  
Acetone Hydrogenation

The problem of kinetics of skeletal nickel samples saturation with hydrogen in an aqueous solution of 2-propanol of azeotropic composition was discussed. 2-propanol dehydrogenation and acetone hydrogenation rate constants were calculated. Kinetic model of processes under study was offered.

The non-stationary polymerization of styrene by HCIO 4 in CH 2 CI 2

1976 ◽  
Vol 351 (1667) ◽  
pp. 551-568 ◽  
Keyword(s):  
Rate Constants ◽  
Methylene Chloride ◽  
Dissociation Constants ◽  
Propagation Rate ◽  
Polymer Chains ◽  
Stage I ◽  
Electrically Conducting ◽  
Steady Stage ◽  
Ionic Components ◽  
Kinetics Of

The non-stationary precursor reaction (stage I) in the polymerization of styrene by perchloric acid in methylene chloride has been examined, by stopped-flow methods over the range 0 to –80 °C. At all temperatures there is evidence of a transient, electrically conducting, intermediate species, absorbing at 340 nm, which reaches its peak concentration at times ranging from 0.1s at 0° C to 0.5–3s at –80 °C (variable with reagent concentra­tions). At the low monomer concentrations (< 0.2M) accessible to the technique, stage I can be quantitatively discriminated from the subsequent steady stage II only below ca . –60 °C. At these low temperatures, contrary to expectations, the conversion during stage I proves to be by a dual mech­anism, the ionic reaction producing no more than about half the mass of polymer and a much smaller fraction of the number of polymer chains. The overall time-scale of stage I appears to be determined primarily by that of removal of free HCIO 4 by the non-ionic mechanism, rather than by the kinetics of the ionic polymerisation. The overall conversions cannot therefore be analysed to yield ionic rate constants. In reactions in presence of the salt n -Bu 4 NCIO 4 , the instantaneous rates can be separated into their non-ionic and ionic components, and approxi­mate values derived for the paired-ion propagation rate constants. k ± p 2000 at –80 °C; 4000–5000 at –60 °C; (unit: dm 3 mol –1 s –1 ). A more speculative analysis of the rates in salt-free systems permits estimates of the free ion propagation constants some 10–20 times the above values, and of ion-pair dissociation constants in the region of 1–5 x 10 –7 mol dm –3 at –60 to –80 °C.

DEVELOPING OF MATLAB APPLICATION FOR DETERMINING THE REACTION KINETICS OF RUBBER VULCANIZATION PROCESS

2021 ◽  
Author(s):  
Dario Balaban ◽  
◽  
Jelena Lubura ◽  
Predrag Kojić ◽  
Jelena Pavličević ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Reaction Kinetics ◽  
Kinetic Parameters ◽  
Degradation Process ◽  
Complex Process ◽  
Quality Of Fit ◽  
Kinetics Of ◽  
Vulcanization Process

Rubber vulcanization is kinetically a complex process, since it consists of two simultaneous reactions: curing and degradation. To determine reaction kinetics, it is necessary to determine a kinetic model which describes the process adequately. Proposed kinetic model has six adjustable parameters. In order to determine kinetic parameters of the proposed kinetic model, commercially available rubber gum was used. Oscillating disc rheometer was used to investigate experimental dependence of torque on time, at six temperatures in the range from 130 to 180 °C, with a step of 10 °C. Matlab application, built via App Designer feature, was developed in order to fit the experimental data to the proposed kinetic model. Developed Matlab application, consisting of two tabs, enables user to upload raw rheometer data, perform manual fitting or automatic fitting (manual or automatic estimation of initial values of adjustable parameters), test the effect of constant values of some kinetic parameters on the overall quality of fit, visualize the dependence of kinetic parameters on temperature and to determine the values of Arrhenius expression for curing and degradation process. Both fitting methods were proven to be efficient; overall determination coefficient and MAPE value for automatic and manual fitting methods were >0.99 and <1%, and >0.999 and <1%, respectively. Arrhenius parameters were also determined with high accuracy (R2>0.98). Developed application enables simple and efficient determination of kinetic parameters by means of different fitting methods, simultaneous fitting of data on all temperatures, and testing the effect of constant kinetic parameters values on fitting results

Kinetics of anaerobic cometabolism of 2,4-dinitrotoluene with ethanol as the primary substrate

1997 ◽  
Vol 36 (6-7) ◽  
pp. 271-278 ◽  
Author(s):  
Jiayang Cheng ◽  
Makram T. Suidan ◽  
Albert D. Venosa
Keyword(s):  
Kinetic Model ◽  
Kinetic Parameters ◽  
Competitive Inhibition ◽  
Methanogenic Bacteria ◽  
Experimental Results ◽  
Marquardt Algorithm ◽  
Levenberg Marquardt ◽  
Kinetics Of ◽  
Primary Substrate

A kinetic model that describes the anaerobic cometabolism of 2,4-dinitrtoluene (DNT) with ethanol as the primary substrate has been developed based on experimental results. The kinetic parameters were estimated using the Levenberg-Marquardt algorithm. 2,4-DNT is anaerobically biotransformed to 2,4-diaminotoluene (DAT) via 4-amino-2-nitrotoluene (4-A-2-NT) and 2-amino-4-nitrotoluene (2-A-4-NT) by the bacteria whose growth is supported by utilizing ethanol. 2,4-DNT shows inhibition to its own biotransformation. It also exhibits a very strong competitive inhibition to further biotransformation of 4-A-2-NT and 2-A-4-NT. All the aromatics in the system, 2,4-DNT, 4-A-2-NT, 2-A-4-NT, and 2,4-DAT, inhibit the conversion of ethanol. Hydrogen produced from the acetogenesis of ethanol is utilized for the transformation of the nitroaromatics. The utilization of hydrogen and acetate by methanogenic bacteria is very strongly inhibited by the presence of the nitroaromatics. Acetate exhibits strong competitive inhibition to the biodegradation of propionate.

scholarly journals THE PHOTOINITIATED ADDITION OF MERCAPTANS TO OLEFINS: III. THE KINETICS OF THE ADDITION OF THIOPHENOL TO STYRENE AND TO 1-OCTENE

1957 ◽  
Vol 35 (7) ◽  
pp. 723-733 ◽  
Author(s):  
R. H. Pallen ◽  
C. Sivertz
Keyword(s):  
Free Radical ◽  
Rate Constants ◽  
Chain Transfer ◽  
Kinetic Studies ◽  
Activation Energies ◽  
Reverse Reaction ◽  
Kinetics Of

Kinetic studies were made of the free radical photoinitiated addition of thiophenol to 1-octene and to styrene in the absence of oxygen. In addition to the usual attack, chain transfer, and termination steps, it is found that a reverse reaction accompanies the attack step, [Formula: see text] The rate constants for the thiophenol–styrene reaction were calculated to be [Formula: see text]kt = 2 × 107 liters.moles−1sec.−1. The over-all activation energies for the two reactions were found to be E (1-octene) = 1.2 kcal., E (styrene) = 2.4 kcal.; suggestions are submitted as to why these activation energies are so low. These reactions are compared with n-butyl mercaptan – olefin reactions.

Kinetics and mechanisms of some reactions of aqueous sodium bromite

1979 ◽  
Vol 57 (12) ◽  
pp. 1524-1530 ◽  
Author(s):  
C. L. Lee ◽  
M. W. Lister
Keyword(s):  
Aqueous Solutions ◽  
Kinetic Parameters ◽  
Rate Constants ◽  
Aqueous Sodium ◽  
Carbonate Ions ◽  
Kinetics Of

The kinetics of the reactions of aqueous bromite ions with basic aqueous solutions of iodide, sulphite, formate, and thiosulphate ions have been investigated. The products are, respectively, iodate, sulphate, and carbonate ions, and with thiosulphate either tetrathionate or sulphate depending on the conditions. The reaction with formate is autocatalytic, being catalysed by carbonate ions. All the reactions show some dependence on hydroxide concentration, and in general k(apparent) = k1 + k2[OH−]−1. The various rate constants have been obtained, as have the associated kinetic parameters. The relative rates of the reactions of bromite ions parallel those of the corresponding reactions of hypochlorite ions, but at 25 °C K is smaller by a factor of roughtly 105.

scholarly journals Further study on kinetic modeling of sunflower oil methanolysis catalyzed by calcium-based catalysts

2016 ◽  
Vol 22 (2) ◽  
pp. 137-144 ◽  
Author(s):  
Marija Miladinovic ◽  
Marija Tasic ◽  
Olivera Stamenkovic ◽  
Vlada Veljkovic ◽  
Dejan Skala
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Kinetic Model ◽  
Sunflower Oil ◽  
Coefficient Of Determination ◽  
Reaction Conditions ◽  
High Coefficient ◽  
Relative Percentage ◽  
Kinetics Of ◽  
Good Agreement

The kinetic model, which was originally developed for sunflower oil methanolysis catalyzed by CaO.ZnO, was examined for several other calcium-based catalysts like neat CaO, quicklime and Ca(OH)2. This model including triacylglycerols mass transfer- and chemically-controlled regimes demonstrated a good agreement with the experimental data in terms of a high coefficient of determination (0.971?0.022) and acceptable mean relative percentage deviation (?15.9%). Hence, this model is recommended for modeling the kinetics of sunflower oil methanolysis over calcium-based catalysts under widely ranging reaction conditions.

scholarly journals Kinetics of the sunflower oil ethanolysis using CaO as catalyst

2016 ◽  
Vol 22 (4) ◽  
pp. 409-418 ◽  
Author(s):  
Ana Velickovic ◽  
Jelena Avramovic ◽  
Olivera Stamenkovic ◽  
Vlada Veljkovic
Keyword(s):  
Kinetic Model ◽  
Sunflower Oil ◽  
Reaction Rate Constant ◽  
Ethyl Esters ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Reaction Conditions ◽  
Data Points ◽  
Kinetics Of ◽  
Good Agreement

The ethanolysis of sunflower oil catalyzed by calcium oxide was studied in wider ranges of the reaction conditions: temperature 65-75?C, ethanol-to-oil molar ratio 6:1-18:1 and catalyst loading 10-20% in order to determine the reaction kinetics. The proposed kinetic model of the sunflower oil ethanolysis included the changing and first-order reaction mechanism with respect to triacylglycerols and fatty acid ethyl esters. The kinetic parameters were determined and correlated with the process variables. The Arrhenius equation could be applied to the reaction rate constant with the activation energy of 94.0 kJ/mol. The proposed kinetic model showed a good agreement with the experimental data with the mean relative percentage deviation of ?13% (based on 256 data points).

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