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.

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.

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.

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.

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.

Studies on Curing Kinetics Parameter of TDI-PPG-MOCA Polyurethane by FTIR

2011 ◽  
Vol 328-330 ◽  
pp. 966-969 ◽  
Author(s):  
Qing Zhen Wen ◽  
Chao Yu ◽  
Jin Hua Zhu ◽  
Tian Yu Liu
Keyword(s):  
Reaction Rate ◽  
Curing Kinetics ◽  
Crosslinking Reaction ◽  
Curing Process ◽  
Second Order Reaction ◽  
Reaction Rate Constants ◽  
Curing Reaction ◽  
Different Temperatures ◽  
Measured Effect ◽  
Kinetics Parameter

The curing process of polyurethanes was investigated with FTIR method. The curves of conversion (α)VS curing reaction time (t) at different temperatures were obtained .The curing reaction of the system was found to be second order reaction. The reaction rate constants and activation energy had been measured. Effect of the use lever of curing agent and temperatures on curing reaction was discussed. The results showed that when the mole ratio of NCO/OH is smaller than 1, the crosslinking reaction take place at high temperature.

scholarly journals Kinetics of winter deacclimation in response to temperature determines dormancy status and explains budbreak in differentVitisspecies

2018 ◽  
Author(s):  
Alisson P. Kovaleski ◽  
Bruce I. Reisch ◽  
Jason P. Londo
Keyword(s):  
Cold Hardiness ◽  
Effect Of Temperature ◽  
Good Prediction ◽  
Chilling Requirement ◽  
Perennial Plant ◽  
Different Temperatures ◽  
Winter Cold ◽  
Response To Temperature ◽  
The Relationship ◽  
Kinetics Of

2.AbstractBud dormancy and cold hardiness are critical adaptations for surviving winter cold stress for temperate perennial plant species, with shifting temperature-based responses during the winter. The objective of this study was to uncover the relationship between dormancy transition (chilling requirement) and temperature on the loss of cold hardiness and budbreak. Dormant cuttings ofVitis vinifera,V. aestivalis,V. amurensis, andV. ripariawere examined to determine the relationship between chilling requirement and temperature on rate of deacclimation (kdeacc). Differential thermal analysis was used to determinekdeaccusing mean low temperature exotherms. Effect of chill was evaluated as the deacclimation potential (ψdeacc), which was the change inkdeaccdue to chill accumulation. Budbreak was also evaluated in fully chilled buds at different temperatures. Results indicate that ψdeaccvaries dependent on dormancy state, following a logarithmic response to chill accumulation. The effect of temperature onkdeaccwas exponential at low and logarithmic at high temperatures. The combination of ψdeaccandkdeaccresulted in good prediction of deacclimation. Budbreak phenology was also explained by differences inkdeacc. Deacclimation rates can be used as a quantitative determinant of dormancy transition and budbreak, and to refine models predicting effects of climate change.

scholarly journals The Curing Kinetics of Multiscale [Ni(EDTA)]-2 Intercalated Zn-Al Layered Double Hydroxides: Glass Fiber–Epoxy Composite Prepreg

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Reza Darvishi ◽  
Mahdi Darvishi ◽  
Ali Moshkriz
Keyword(s):  
Glass Fiber ◽  
Layered Double Hydroxides ◽  
Cure Kinetics ◽  
Curing Kinetics ◽  
Scanning Calorimetry ◽  
Curing Behavior ◽  
Autocatalytic Model ◽  
Experimental Findings ◽  
Double Hydroxides ◽  
Kinetics Of

In the present research, the effect of Zn2Al layered double hydroxides (LDH) and nickel (II)-EDTA complex intercalated LDH (LDH-[Ni(EDTA)]-2) on the cure kinetics of glass fiber/epoxy prepreg (GEP) was explored using nonisothermal differential scanning calorimetry (DSC). The results showed that LDH caused a shift in the cure temperature toward lower temperatures while accelerating the curing of epoxy prepregs. The use of LDH-[Ni(EDTA)]-2 more profoundly influenced the acceleration of the curing process. The curing kinetics of prepregs was assessed through the differential isoconversional Friedman (FR) technique and the integration method of Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS). A decrease was detected in the E α value of glass fiber/LDH-[Ni(EDTA)]-2/epoxy (GELP) and glass fiber/LDH-[Ni(EDTA)]-2/epoxy (GELNiP) prepregs at small cure degrees relative to GEP, suggesting the catalytic effect of LDH or LDH-[Ni(EDTA)]-2 on the initial epoxy/amine reaction. Furthermore, LDH-[Ni(EDTA)]-2 performed better due to the catalyst role of nickel (II). Moreover, the activation energy exhibited lower reliance on the degree of conversion in the cases of GELP and GELNiP rather than pure epoxy prepregs. An autocatalytic model was used to evaluate the curing behavior of the system. Based on the results, the curing reaction of the epoxy prepreg can be described by the autocatalytic Šesták-Berggren model even after the incorporation of LDH or LDH-[Ni(EDTA)]-2. The kinetic parameters of the autocatalytic model (such as E α , A , m , n ) and the equations explaining the curing behavior of prepregs were introduced as well whose predictions were in line with the experimental findings.

Effect of Temperature and Bicarbonate Concentration on the Kinetics of UO2(s) Dissolution Under Oxidizing Conditions

1996 ◽  
Vol 465 ◽  
Author(s):  
J. de Pablo ◽  
I. Casas ◽  
J. Giménez ◽  
M. Molera ◽  
M. E. Torrero
Keyword(s):  
Dissolution Rate ◽  
Solid Particles ◽  
Effect Of Temperature ◽  
Bicarbonate Concentration ◽  
Rate Laws ◽  
Carbonate Concentration ◽  
Hydrogen Carbonate ◽  
Different Temperatures ◽  
Flow Through ◽  
Kinetics Of

ABSTRACTThe dissolution rate of unirradiated UO2 (s) has been studied as a function of hydrogen carbonate concentration at three different temperatures (298.15 K, 313.15 K and 333.15 K) under oxidizing conditions in a continuous flow-through reactor with a thin layer of solid particles (particle size from 100 to 300 μm). From the results of these experiments, two different rate laws have been determined. At high temperature (313.15 K and 333.15 K), we obtained a dissolution rate proportional to hydrogen carbonate concentration while at 298.15 K, the rate almost depends on the square root of the hydrogen carbonate concentration. This indicates a different reaction mechanism depending on temperature which can be related to the oxidation step of the overall process. The apparent activation energy obtained was 41 kJ mo1−1.

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.

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.

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