Isothermal transformation of dynamic DSC curves for thermosetting polymers in curing kinetics analysis

Abstract

To predict the isothermal course of a reaction from the dynamic DSC curves, the application of isothermal DSC curve transformation has been proposed. To perform such a transformation, it is sufficient only to determine the effective activation energy. To transform integral dynamic curves, a(T)), into isothermal ones, a(t), a better equation has been derived and its validity has been demonstrated on the example of two typical thermosetting ~]~tems. In addition, it hasd~een shown that the transformation of differential curves, (T), into isothermal ones -~-(a), readily allows determination of the kinetic function and rate constants. The procedure used to obtain information on the curing kinetics for thermosetting resins is characterized by simplicity and reliability and can work at E = E(a).

Vulcanization of EPDM rubber compounds with and without blowing agents: Identification of reaction events and TTT-diagram using DSC data

“…This heat can be used to study the rate of vulcanization. Assuming that the exothermic heat during vulcanization is proportional to the extent of monomer conversion, vulcanization kinetics and physical information can be estimated from dynamic and isothermal DSC tests . The reaction can be monitored using a relationship between heat and curing degree, c= Q / Q T , where Q T is the total heat released during a reaction.…”

Method for time–temperature–transformation diagrams using DSC data: Linseed aliphatic epoxy resin

“…Differential Scanning Calorimetry (DSC) technique measures the instantaneous heat, , from a reactive sample as a function of temperature; it can be used directly, accurately and fast to study the rate of cure from the reaction heat. Assuming that the exothermic heat during cure is proportional to the extent of monomer conversion, cure kinetics and physical information can be estimated from dynamic and isothermal DSC tests . Therefore, the reaction can be monitored using a relationship between heat and curing degree, (where is the total heat released during a reaction).…”

Different kinetic equations analysis

“…K. Kretzchmar [2] observed a similar behaviour at the time of an epoxy resin study, in which it was established that the kinetic homogeneous law, applied to Ellerstein's method, expresses only 40% of the phenomenon studied. Numerous authors [3][4][5][6][7] agree in thinking that it is often indispensable to compare results obtained in differential scanning analysis with results obtained in a different way to be able to decide between several reaction mechanisms. Thus, many [3][4][5][6] assert that it is necessary to carry out measurements by an isothermal method, to avoid some mistakes which could be committed during a kinetic study obtained only an-isothermally.…”