Formal kinetic evaluation of reactions with partial diffusion control

A plethora of models have been developed quantifying the effect of diffusion‐controlled phenomena on polymerization reactions. The most prominent approaches are reviewed here, including innovative ones that have emerged over the last decade. Free‐radical and step‐growth polymerizations are considered in a way to show that similar models have been used in both mechanisms. In free‐radical polymerization the models proposed are subdivided according to their theoretical background into four categories: (i) based on a Fickian description of reactant diffusion; (ii) free‐volume theory based; (iii) chain‐length dependent; and, (iv) empirical. The reversible addition‐fragmentation technique is discussed, together with two industrially important case‐studies, solid state polycondensation and epoxy‐amine curing.magnified image

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“…However, it was extensively used recently in modeling the effect of diffusion phenomena in epoxy-amine curing. [200][201][202][203] …”

Section: A Review Of Modeling Of Diffusion Controlled Polymerization mentioning

confidence: 99%

A Review of Modeling of Diffusion Controlled Polymerization Reactions

Achilias¹

2007

Macro Theory & Simulations

234

292

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“…The most well-known and most frequently applied model for epoxy reaction kinetics is the Kamal's autocatalytic model. 9,10,27 However, Montserrat and Málek 11 have indicated that the curing reaction kinetics of a DGEBA cured with both a hardener derived from a methyl tetrahydrophthalic anhydride and a tertiary amine as accelerator is described more accurately by the two-parameter autocatalytic model of Sesták-Berggren:…”

Section: Curing Kinetics Modelingmentioning

confidence: 99%

TTT‐cure diagram of an anhydride‐cured epoxy system including gelation, vitrification, curing kinetics model, and monitoring of the glass transition temperature

Teil

Page

Michaud

et al. 2004

J of Applied Polymer Sci

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ABSTRACT:The curing reaction of an epoxy resin [diglycidyl ether of bisphenol A (DGEBA)] combined with a methyl-hexahydrophtalic anhydride (MHHPA) hardener and a benzyldimethylamine (BDMA) accelerator was studied over a temperature range of 60 -140°C to build its isothermal time-temperature-transformation (TTT)-cure diagram. This includes gelation and vitrification measurements using rheological measurement techniques, monitoring of the glass transition temperature and the reaction kinetics by differential scanning calorimetry, and determination of the following critical glass transition temperatures: T g0 , Gel T g , and T gϱ . A new curing kinetics model, based on the Sesták-Berggren model, was developed including both chemicaland diffusion-controlled stages of reaction. Then, the TTTcure diagram was built by numerical integration of the kinetics model, and good agreement was obtained by comparison with experimental data. Additionally, for the first time, this model takes into account the incomplete cure, which occurs when the thermosetting system is cured below its ultimate glass transition temperature, leading to a more realistic description of the cure evolution after vitrification.

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“…R is the universal gas constant (expressed in units of kJ mol À1 K À1 ). The reaction model may take various forms based on nucleation and nucleus growth, phase boundary reaction, diffusion, and chemical reaction [10,13,19,21,[25][26][27][28][31][32][33][34][35][36]. In the present investigation, we have applied fifteen such well-known models for thermal degradation kinetics using single step/multi step and multi-heating rates.…”

Section: Multi-steps and Multi-heating Rates Model Fitting Methods Formentioning

confidence: 99%

“…in the model equations [25][26][27][28]. Yet the selections of appropriate models [19,20,[22][23][24][25][26][27][28][29], oversimplified approximation of temperature integral [10] and initial guess of kinetics parameters are major drawbacks of model fitting methods [26]. Hybrid genetic algorithm (HGA) successfully overcomes the above-mentioned problems for the estimation of kinetics parameters.…”

Section: Introductionmentioning

confidence: 99%