Phenomenological model for the reaction order n in the kinetics of curing an elastomer EPDM

MRS Advances ◽  
2019 ◽  
Vol 4 (59-60) ◽  
pp. 3299-3310
Author(s):  
S. Gómez-Jimenez. ◽  
A.M. Becerra-Ferreiro. ◽  
E. Jareño-Betancourt. ◽  
J. Vázquez-Penagos.
Keyword(s):  
Reaction Order ◽  
Cure Kinetics ◽  
Analytical Description ◽  
Crosslinking Reaction ◽  
Precise Control ◽  
Short Period ◽  
Rate Of Reaction ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Modelling And Optimization

AbstractThe precise control of curing reaction parameters allows a better crosslinking polymer. Modelling and optimization of this process require a correct kinetic of curing model. The kinetics of the crosslinking reaction is studied for the ethylene propylene diene monomer (EPDM) synthetic elastomer by mobile die rheometer (MDR). The kinetic parameters of reaction were calculated from Kamal-Ryan, Sestak-Berggren, and the Isayev-Deng methods at different temperatures. An Arrhenius-type function for the order of reaction n is introduced to improve the adjusting. Finally, a graphical and analytical description of the cure kinetics was developed. The order of reaction is predicted to better establishment of processing time. It was noted that for EPDM at higher temperatures, the increase of the rate of reaction occurs in short period of time, which could cause premature curing if the supply system is inadequate.

Phenomenological effect of temperature on the order n of the reaction of the curing kinetics in an EPDM polymer

2021 ◽  
pp. 1-12
Author(s):  
Salvador Gomez-Jimenez ◽  
Ana Maria Becerra-Ferreiro ◽  
Eduardo D Jareño-Betancourt ◽  
Jose M Vazquez-Penagos
Keyword(s):  
Cure Kinetics ◽  
Analytical Description ◽  
Curing Kinetics ◽  
Effect Of Temperature ◽  
Crosslinking Reaction ◽  
Precise Control ◽  
The Best Approximation ◽  
Short Period ◽  
Different Temperatures ◽  
Kinetics Of

Abstract The precise control of curing reaction parameters allows a better crosslinking polymer. Modeling and optimization of this process require a correct kinetic of curing model. The kinetics of the crosslinking reaction is studied for the ethylene propylene diene monomer (EPDM) synthetic elastomer by movile die rheometer (MDR). The kinetic parameters of reaction were calculated from Kamal-Ryan, Sestak-Berggren, and the Isayev-Deng methods at different temperatures. An Arrhenius-type function for the order of reaction n is introduced to improve the adjusting. A comparative study of Sestak-Berggren and Isayev-Deng models was made to validate and determine which model best describes the behavior of vulcanization. The best approximation was obtained with the model Isayev-Deng. Finally, taking the model with the best fit, a graphical and analytical description of the cure kinetics was developed. The order of reaction is predicted to better establishment of processing time. It was noted that for EPDM at higher temperatures, the increase of the rate of reaction occurs in short period of time, which could cause premature curing if the supply system is inadequate.

scholarly journals Effect of Nickel Doping on the Cure Kinetics of Epoxy/Fe3O4 Nanocomposites

2020 ◽  
Vol 4 (3) ◽  
pp. 102
Author(s):  
Maryam Jouyandeh ◽  
Zohre Karami ◽  
Seyed Mohammad Reza Paran ◽  
Amin Hamed Mashhadzadeh ◽  
Mohammad Reza Ganjali ◽  
...  
Keyword(s):  
Short Communication ◽  
Cure Kinetics ◽  
Partial Replacement ◽  
Crosslinking Reaction ◽  
Kinetics Analysis ◽  
Scanning Calorimetry ◽  
Nickel Doping ◽  
Cure Kinetic ◽  
Rate Of Reaction ◽  
Kinetics Of

This short communication aims to evaluate the cure kinetics of epoxy/NixFe3−xO4 nanocomposites. Differential scanning calorimetry (DSC) provided support for cure kinetics analysis based on the variation of activation energy (Eα) as a function of the extent of crosslinking reaction, α. The average values of Eα calculated based on Kissinger and Friedman methods were 59.22 and 57.35 kJ/mol for the neat epoxy, 43.37 and 48.74 kJ/mol for the epoxy/Fe3O4, and eventually 50.48 and 49.19 kJ/mol for the epoxy/NixFe3−xO4 nanocomposites. The partial replacement of Fe2+ ion sites in the Fe3O4 crystal lattice by the Ni2+ ions changed to some content the cure kinetic profile because of the fact that a lower level of energy was needed for curing by incorporation of NixFe3−xO4 into the epoxy matrix. The rate of reaction calculated theoretically adequately fitted with experimental profiles obtained in DSC experiments.

Effects of additives on the cure kinetics of vinyl ester pultrusion resins

2021 ◽  
pp. 002199832110015
Author(s):  
Alexander Vedernikov ◽  
Yaroslav Nasonov ◽  
Roman Korotkov ◽  
Sergey Gusev ◽  
Iskander Akhatov ◽  
...  
Keyword(s):  
Vinyl Ester ◽  
Mean Squared Error ◽  
Cure Kinetics ◽  
Zinc Stearate ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Different Temperatures ◽  
Predicted Values ◽  
Kinetics Of ◽  
Final Degree

Pultrusion is a highly efficient composite manufacturing process. To accurately describe pultrusion, an appropriate model of resin cure kinetics is required. In this study, we investigated cure kinetics modeling of a vinyl ester pultrusion resin (Atlac 430) in the presence of aluminum hydroxide (Al(OH)3) and zinc stearate (Zn(C18H35O2)2) as processing additives. Herein, four different resin compositions were studied: neat resin composition, composition with Al(OH)3, composition comprising Zn(C18H35O2)2, and composition containing both Al(OH)3 and Zn(C18H35O2)2. To analyze each composition, we performed differential scanning calorimetry at the heating rates of 5, 7.5, and 10 K/min. To characterize the cure kinetics of Atlac 430, 16 kinetic models were tested, and their performances were compared. The model based on the [Formula: see text]th-order autocatalytic reaction demonstrated the best results, with a 4.5% mean squared error (MSE) between the experimental and predicted data. This study proposes a method to reduce the MSE resulting from the simultaneous melting of Zn(C18H35O2)2. We were able to reduce the MSE by approximately 34%. Numerical simulations conducted at different temperatures and pulling speeds demonstrated a significant influence of resin composition on the pultrusion of a flat laminate profile. Simulation results obtained for the 600 mm long die block at different die temperatures (115, 120, 125, and 130 °C) showed that for a resin with a final degree of cure exceeding 95% at the die exit, the maximum difference between the predicted values of pulling speed for a specified set of compositions may exceed 1.7 times.

Investigating the relationship between tack and degree of conversion in DGEBA-based epoxy resin cured with dicyandiamide and diuron

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ali Kuliaei ◽  
Iraj Amiri Amraei ◽  
Seyed Rasoul Mousavi
Keyword(s):  
Epoxy Resin ◽  
Reaction Order ◽  
Theoretical Data ◽  
Cure Kinetics ◽  
Diglycidyl Ether ◽  
Degree Of Conversion ◽  
Ozawa Method ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Kinetics Of

Abstract The purpose behind this research was to determine the optimum formulation and investigate the cure kinetics of a diglycidyl ether of bisphenol-A (DGEBA)-based epoxy resin cured by dicyandiamide and diuron for use in prepregs. First, all formulations were examined by the tensile test, and then, the specimens with higher mechanical properties were further investigated by viscometry and tack tests. The cure kinetics of the best formulation (based on tack test) in nonisothermal mode was investigated using differential scanning calorimetry at different heating rates. Kissinger and Ozawa method was used for determining the kinetic parameters of the curing process. The activation energy obtained by this method was 71.43 kJ/mol. The heating rate had no significant effect on the reaction order and the total reaction order was approximately constant ( m + n ≅ 2.1 $m+n\cong 2.1$ ). By comparing the experimental data and the theoretical data obtained by Kissinger and Ozawa method, a good agreement was seen between them. By increasing the degree of conversion, the viscosity decreased; as the degree of conversion increased, so did the slope of viscosity. The results of the tack test also indicated that the highest tack could be obtained with 25% progress of curing.

Vulcanization of Elastomers. 25. Natural Rubber and Synthetic Elastomers with Sulfur and Sulfenamides. I

1960 ◽  
Vol 33 (3) ◽  
pp. 846-856 ◽  
Author(s):  
Walter Scheele ◽  
Horst-Eckart Toussaint ◽  
Yoan-Kun Chai
Keyword(s):  
Reaction Order ◽  
Molar Ratio ◽  
Reactive Intermediate ◽  
Sulfur Concentration ◽  
Kcal Mole ◽  
Experimental Conditions ◽  
Sulfur Vulcanization ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Time Plot

Abstract The sulfur vulcanization of Perbunan N 2818 (acrylonitrile-butadiene) was investigated in the presence of N-cyclohexyl-2-benzothiazolylsulfenamide (CZ) at different temperatures and various concentrations of reactants. The following were found : 1. The decreasing sulfur concentration vs. time plot followed the 0.8th order under all experimental conditions and an activation energy of 28.2 kcal/mole was calculated. 2. When using the cyclohexylammonium salt of MBT as accelerator, sulfur decrease proceeds at the same rate as with CZ. 3. It was concluded from 1 and 2 that even in the presence of CZ, the ammonium salt was the actual accelerator, which forms during the scorch or induction period through reaction of CZ with the rubber. 4. In view of the discrepancy found in the relation of reaction order with respect to time and concentration of reactants, the formation of a reactive intermediate is postulated; the analogy between the kinetics of sulfenamide accelerated sulfur vulcanization, and those accelerated with MBT as well as DPG is pointed out. 5. In connection with 3 the dependence of starting rate as well as rate constant of 0.8th order of the decreasing sulfur concentration on the molar ratio of CZ/S8 and on the sulfur starting concentration is discussed.

THE REACTION BETWEEN CYANATE AND HYPOCHLORITE

1956 ◽  
Vol 34 (4) ◽  
pp. 489-501 ◽  
Author(s):  
M. W. Lister
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Rate Constant ◽  
Hypochlorous Acid ◽  
Effect Of Temperature ◽  
Slow Step ◽  
True Activation Energy ◽  
Rate Of Reaction ◽  
Different Temperatures ◽  
Kinetics Of

The reaction between sodium hypochlorite and potassium cyanate in the presence of sodium hydroxide has been examined. The main products are chloride, and carbonate ions and nitrogen; but, especially if much hypochlorite is present, some nitrate is formed as well. The rate of reaction is proportional to the cyanate and hypochlorite concentrations, but inversely proportional to the hydroxide concentration: the rate constant is 5.45 × 10−4 min.−1 at 65 °C, at an ionic strength of 2.2. The rate constant increases somewhat as the ionic strength rises from 1.7 to 3.5. The effect of temperature makes the apparent activation energy 25 kcal./gm-molecule. The kinetics of the reaction suggest that the slow step is really a reaction of hypochlorous acid and cyanate ions, and possible intermediate products of this reaction are suggested. Allowing for the different extent of hydrolysis of hypochlorite at different temperatures, the true activation energy is found to be 15 kcal./gm-mol., which is consistent with the observed rate of reaction.

scholarly journals Kinetics of Thermal Degradation of Recycled Polyvinyl Chloride Resin

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
I. M. Alwaan
Keyword(s):  
Thermal Degradation ◽  
Polyvinyl Chloride ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Rate Of Reaction ◽  
Different Temperatures ◽  
Zero Order Reaction ◽  
Enthalpy And Entropy ◽  
Kinetics Of ◽  
Entropy Of Reaction

The goal of this study is to find the effect of time and temperature on the thermal degradation of recycled polyvinyl chloride (PVC) resin. The isothermal rate of reaction(r)of recycled PVC resin was investigated at the following temperatures to: 100, 110, 120, 130, and 140°C at period of times ranging from 10 to 50 min. The result shows that the rate of reaction(r)of recycled PVC increases with increasing temperatures. The reaction rate constant(K)for temperatures ranging from 100 to 140°C was doubled from 0.028–0.056 mol·L−1·S−1. The process was found to be zero order reaction at all range of temperatures 100–140°C. The activation energy of the thermal weight loss was calculated at different temperatures(E/R = 2739.5°K). The average enthalpy and entropy of reaction at temperature of 298°K were determined.

Kinetics of Urethan Cleavage in Crosslinked Polyurethans

1967 ◽  
Vol 40 (4) ◽  
pp. 1230-1237
Author(s):  
Ajaib Singh ◽  
Leonard Weissbein
Keyword(s):  
Stress Relaxation ◽  
Relaxation Data ◽  
Network Chain ◽  
Transient Stress ◽  
Precise Control ◽  
Positive Identification ◽  
Thermodynamic Constants ◽  
Different Temperatures ◽  
Order Of Magnitude ◽  
Kinetics Of

Abstract A series of clean, well defined polyurethan networks was synthesized from polyester glycols, 2, 4-tolylene diisocyanate, and 1, 1′, 1″-trimethylolpropane by means that afforded precise control over the content of urethan groups per network chain. The thermal cleavage of these networks was studied using the technique of stress relaxation. Analysis of the stress relaxation data on each network structure revealed two exponential decay processes differing in rate by about an order of magnitude. The rate of the slower process, which dominates the overall stress decay, was shown to be directly dependent on the content of urethan groups per network chain. Positive identification of this process with urethan cleavage was thereby established. The kinetic and thermodynamic constants associated with urethan cleavage were then calculated from data on this process at different temperatures. The more transient stress decay process was not uniquely definable, but probably originated from the cleavage of one or more types of weak linkages found in small but variable proportions in the different polyurethan networks. The nature and origin of these weak linkages was discussed.

Non-Isothermal Curing Kinetics of a Modified Benzoxazine Resin System Suitable for Hot-Melt Prepreg Preparation

2017 ◽  
Vol 266 ◽  
pp. 128-134 ◽  
Author(s):  
Meng Jin Fan ◽  
Yu Zhou ◽  
Yi Hao Luan ◽  
Qian Zang ◽  
Dong Xia Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Cure Kinetics ◽  
Curing Kinetics ◽  
Curing Temperature ◽  
Resin System ◽  
Average Value ◽  
Significant Difference ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Hot Melt

Non-isothermal DSC was used to study the cure kinetics of a flame-retardant benzoxazine resin system (BZ501-1) suitable for hot-melt prepreg preparation. The variation of activation energy with conversion for BZ501-1 system was investigated by using Flynn-Wall-Ozawa method, and the average value of activation energy obtained from this method was 100.5 kJ/mol. After that, the model function that depends on the reaction mechanism for the non-isothermal cure of BZ501-1 system was determined by Málek method, and the result showed that Šesták-Berggren model can generally simulate well the reaction rate. Finally, the isothermal curing behavior of BZ501-1 at 200 °C was predicted by using the obtained rate equation, and the result showed that there was no significant difference between the experiment conversions and the predicted ones. The predicted results at different temperatures indicated that the curing rate increased gradually with increasing the curing temperature.

scholarly journals Rheokinetic Analysis of Hydroxy Terminated Polybutadiene Based Solid Propellant Slurry

2010 ◽  
Vol 7 (1) ◽  
pp. 171-179 ◽  
Author(s):  
Abhay K Mahanta ◽  
Monika Goyal ◽  
Devendra D Pathak
Keyword(s):  
Shear Rate ◽  
Rate Constants ◽  
Cure Kinetics ◽  
Toluene Diisocyanate ◽  
Quenching Temperature ◽  
Warm Up ◽  
Reaction Rate Constants ◽  
Different Temperatures ◽  
Solid Rocket ◽  
Kinetics Of

The cure kinetics of propellant slurry based on hydroxy-terminated polybutadiene (HTPB) and toluene diisocyanate (TDI) polyurethane reaction has been studied by viscosity build up method. The viscosity (ɳ)–time (t) plots conform to the exponential function ɳ = aebt, where a & b are empirical constants. The rate constants (k) for viscosity build up at various shear rate (rpm), evaluated from the slope of dɳ/dtversusɳ plots at different temperatures, were found to vary from 0.0032 to 0.0052 min-1. It was observed that the increasing shear rate did not have significant effect on the reaction rate constants for viscosity build up of the propellant slurry. The activation energy (Eɳ), calculated from the Arrhenius plots, was found to be 13.17±1.78 kJ mole-1, whereas the activation enthalpy (∆Hɳ*) and entropy (∆Sɳ*) of the propellant slurry, calculated from Eyring relationship, were found to be 10.48±1.78 kJ mole-1and –258.51± 5.38 J mole-1K-1, respectively. The reaction quenching temperature of the propellant slurry was found to be -9°C, based upon the experimental data. This opens up an avenue for a “freeze-and-store”, then “warm-up and cast”, mode of manufacturing of very large solid rocket propellant grains.

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