Overall Kinetics of Natural Rubber Vulcanization at High Temperatures I—review of Investigation Techniques, Methods and Previous Results of Kinetic Analysis

1971 ◽  
Vol 44 (5) ◽  
pp. 1316-1325 ◽  
Author(s):  
R. B. Redding ◽  
D. A. Smith
Keyword(s):  
Natural Rubber ◽  
Kinetic Analysis ◽  
Kinetic Parameters ◽  
High Temperatures ◽  
Kinetic Data ◽  
Network Chain ◽  
Correct Determination ◽  
Kinetics Of ◽  
Overall Kinetics

Abstract Analysis of previously published cure data illustrates the importance of correct determination of the ultimate level of network chain density in the absence of reversion, and the correction of each kinetic data point for “reversion contributions”. A graphical procedure is described for the determination of kinetic parameters which takes these precautions into account.

Kinetic analysis of solid-state processes

2001 ◽  
Vol 16 (6) ◽  
pp. 1862-1871 ◽  
Author(s):  
Jiří Málek ◽  
Takefumi Mitsuhashi ◽  
José Manuel Criado
Keyword(s):  
Solid State ◽  
Kinetic Analysis ◽  
Crystallization Process ◽  
Good Description ◽  
Simple Method ◽  
Solid State Kinetics ◽  
Kinetics Of ◽  
Nonisothermal Conditions ◽  
Two Parameter

A simple method for kinetic analysis of solid-state processes has been developed. A criteria capable of classifying different processes is explored here with a view toward visualizing the complexity of solid-state kinetics. They provide a useful tool for the determination of the most suitable kinetic model. The method has been applied to the analysis of crystallization processes in amorphous ZrO2 and RuO2. It is found that the crystallization kinetics of as-prepared sample exhibits a complex behavior under nonisothermal conditions. This is probably due to an overlapping of the nucleation- and crystal-growth processes at the beginning of crystallization. As a consequence, the Johnson–Mehl–Avrami nucleation-growth model cannot be applied. A two-parameter autocatalytic model provides a good description of the crystallization process under isothermal and nonisothermal conditions.

scholarly journals Relationship of Exo-β-d-Galactofuranosidase Kinetic Parameters to the Number of Phosphodiesters in Penicillium fellutanum Peptidophosphogalactomannan: Enzyme Purification and Kinetics of Glycopeptide and Galactofuran Chain Hydrolysis

2001 ◽  
Vol 67 (10) ◽  
pp. 4648-4656 ◽  
Author(s):  
Brigitte A. Tuekam ◽  
Yong-Il Park ◽  
Clifford J. Unkefer ◽  
John E. Gander
Keyword(s):  
Kinetic Parameters ◽  
Kinetic Data ◽  
Inorganic Phosphate ◽  
Enzyme Purification ◽  
Degree Of Polymerization ◽  
Apparent Homogeneity ◽  
Relationship Of ◽  
Kinetics Of ◽  
Hydrolysis Of

ABSTRACT Extracellular Penicillium fellutanumexo-β-d-galactofuranosidase, with a mass of 70 kDa, was purified to apparent homogeneity. The enzyme was used to investigate the influence of phosphodiesters of the peptidophosphogalactomannans pP2GMii and pP25GMii(containing 2 and 25 phosphodiester residues, respectively, per mol of polymer) on the kinetic parameters of galactofuranosyl hydrolysis of these two polymers, of 1-O-methyl-β-d-galactofuranoside, and of two galactofuranooligosaccharides. The enzyme did not hydrolyze phosphorylated galactose residues of pP2GMii or pP25GMii. Thek cat/Km value for pP25GMii is 1.7 × 103M−1 s−1, that for 1-O-methyl-β-d-galactofuranoside is 1.1 × 104 M−1 s−1, that for pP2GMii is 1.7 × 10 4M−1 s−1, and those for 5-O-β-d-galactofuranooligosaccharides with degrees of polymerization of 3.4 and 5.5 are 1.7 × 105 and 4.1 × 105 M−1s−1, respectively. Variability in thek cat/Km values is due primarily to differences in Km values; thek −1/k 1 ratio likely provides the most influence on Km. k cat increases as the degree of polymerization of galactofuranosyl residues increases. Most of the galactofuranosyl and phosphocholine residues were removed by day 8 in vivo from pPxGMii added to day 3 cultures initiated in medium containing 2 mM phosphate but not from those initially containing 20 mM phosphate. The filtrates from day 9 cultures initiated in 2 mM inorganic phosphate in modified Raulin-Thom medium contained 0.2 mM inorganic phosphate and 2.2 U of galactofuranosidase ml−1h−1. No galactofuranosidase activity but 15 mM inorganic phosphate was found in filtrates from day 9 cultures initiated in 20 mM phosphate. In vivo the rate of galactofuranosyl hydrolysis of pPxGMii and of related polymers is proportional to thek cat/Km value of each polymer. The kinetic data show that thek cat/Km value increases as the number of phosphodiesters of pPxGMiidecreases, also resulting in an increase in the activity of exo-β-d-galactofuranosidase.

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 thermal decomposition of aseptic packages

2013 ◽  
Vol 67 (12) ◽  
Author(s):  
Juma Haydary ◽  
Dalibor Susa
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Parameters ◽  
Flow Reactor ◽  
Independent Set ◽  
Kinetics Of Thermal Decomposition ◽  
Thermogravimetric Data ◽  
Type Flow ◽  
Apparent Kinetic Parameters ◽  
Kinetics Of

AbstractKinetics of thermal decomposition of aseptic packages (e.g. Tetrapak cartons) and pyrolysis of this waste in a laboratory flow reactor was studied. Three different models for the calculation of the reaction rate and the determination of apparent kinetic parameters of thermal decomposition were used. The first method assumes a two stage thermal decomposition and the kinetic parameters were determined by fitting a derivative thermogravimetric (DTG) curve to experimentally determined thermogravimetric data of whole aseptic cartons. The second method uses kinetic parameters determined by fitting DTG curves to thermogravimetric data of individual components of aseptic packages. The last method was a multi-curve isoconversion method assuming a change of kinetic parameters with the increasing conversion. All types of the determined kinetic parameters were used in a mathematical model for thermal decomposition of mini briquettes made from aseptic packages at the temperature of 650°C. The model calculated also the heat conduction in the particles and it was verified by an independent set of experiments conducted in a laboratory screw type flow reactor.

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