Journal ArticleDOI
Curing kinetics and chemorheological analysis of polyurethane formation
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TLDR
In this paper, the cross-linking kinetics and the rheological behavior of a polyurethane system during curing are investigated by DSC and small amplitude oscillatory shear rheometry.Abstract:
The cross-linking kinetics and the rheological behavior of a polyurethane system during curing are investigated by DSC and small amplitude oscillatory shear rheometry. In this study, isoconversional methods are applied to understand the reaction complexity. The activation energy depends on the extent of conversion. It can be shown that three parallel reactions occur during the evolution of the global reaction in non-isothermal conditions. An original multi-step model can involve these three parallel independent reactions. Dynamic viscosity is measured as a function of time and is found independent of shear rate. Isothermal viscosity rise is related to reaction extent by a phenomenological model. The gelation time is determined by the tanδ crossover at different frequencies. Polym. Eng. Sci. 44:518–527, 2004. © 2004 Society of Plastics Engineers.read more
Citations
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Isoconversional Kinetic Analysis of Thermally Stimulated Processes in Polymers
TL;DR: Isoconversional analysis of polymer kinetics has been studied extensively over the past decade as discussed by the authors and has been applied to a wide range of applications, including thermal degradation, crosslinking, glass transition, and glass and melt crystallization.
Journal ArticleDOI
ICTAC Kinetics Committee recommendations for collecting experimental thermal analysis data for kinetic computations
Sergey Vyazovkin,Konstantinos Chrissafis,Maria Laura Di Lorenzo,Nobuyoshi Koga,Michèle Pijolat,Bertrand Roduit,Nicolas Sbirrazzuoli,Joan Josep Suñol +7 more
TL;DR: In this paper, the authors present a set of recommendations for obtaining kinetic data that are adequate to the actual kinetics of various processes, including thermal decomposition of inorganic solids; thermal and thermo-oxidative degradation of polymers and organics; reactions of solids with gases; polymerization and crosslinking; crystallization of polymer and inorganics; hazardous processes.
Journal ArticleDOI
Integral, differential and advanced isoconversional methods: Complex mechanisms and isothermal predicted conversion–time curves
TL;DR: In this paper, it was shown that the assumption of a constant activation energy is a key parameter that must be considered in the case of a complex reaction mechanism leading to a great variation of the effective activation energy on conversion.
Journal ArticleDOI
Is the Friedman Method Applicable to Transformations with Temperature Dependent Reaction Heat
TL;DR: In this article, differences in activation energy values are obtained using the Friedman (FR) and the advanced non-linear (NLN) isoconversional methods in the case of chemical reactions with temperature dependent reaction heat.
Journal ArticleDOI
Kinetic and thermodynamic studies of the formation of a polyurethane based on 1,6-hexamethylene diisocyanate and poly(carbonate-co-ester)diol
B. Fernandez d'Arlas,L. Rueda,Pablo Marcelo Stefani,K. de la Caba,Iñaki Mondragon,Arantxa Eceiza +5 more
TL;DR: In this paper, the kinetic and thermodynamic characterization of a non-catalyzed reaction between poly(hexamethylene carbonate- co-caprolactone)diol (PHMC- co -PCL) with a stochastic functional concentration, using both isothermal and dynamic differential scanning calorimetry, DSC, as well as Fourier transform infrared spectroscopy, FT-IR, was presented.
References
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Journal ArticleDOI
Kinetics of thermal degradation of char-forming plastics from thermogravimetry. Application to a phenolic plastic
TL;DR: In this article, a technique was devised for obtaining rate laws and kinetic parameters which describe the thermal degradation of plastics from TGA data, based on the inter-comparison of experiments which were performed at different linear rates of heating.
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Kinetic analysis of thermogravimetric data
TL;DR: The kinetic analysis of the thermogram, by use of either its exact equation or a more convenient approximation formula, is straightforward in cases of volatilization via simple kinetics as mentioned in this paper.
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Can the gel point of a cross-linking polymer be detected by the G′ – G″ crossover?
TL;DR: In this article, it was shown that there is only one class of network polymers for which the gel point coincides with the crossover, and the crossover cannot be used for detecting GP.
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Differential scanning calorimetry of epoxy cure: isothermal cure kinetics☆
S. Sourour,Musa R. Kamal +1 more
TL;DR: In this article, the authors used a differential scanning calorimeter (DSC) under isothermal conditions in the range 50-150°C to collect and process rate and integral heat of reaction data during cure.