Published: CABEQ 18 (1) (2004) 65–71
Paper type: Original Scientific Paper
D. Klinar, J. Golob and M. Krajnc
Lenses (made of allyl monomers like DADC) of different shapes and sizes are produced via free-radical bulk polymerization in a casting process. Preparation of large number products of different sizes can represent a problem because of the heat released during polymerization, which can consequently lead to distortion of the structure. An investigation of the polymerization, using DSC, was performed in order to determine apparent kinetic parameters of the system. Isoconversional multiple heating rate method (MHR) according to Friedman, residual heat analysis of isothermally precured samples and single heat method (SHR), was applied to determine the kinetic parameters. ROn single step reaction model was used to approximate the complex and multi step process. With the application of the “compensation effect” in the form of linear equation lnA = aEa,app + b the possibility to unify the kinetic parameters, from the different methods to common one, was established. Kinetic triplet from the common point Ea,app = 128.23 kJ/mol, lnA = 37.133 (1.34 · 1016 s–1) and f(α) = (1-α)1,33 can be successfully used for the simulations of nonisothermal and isothermal curing processes of DADC initiated with 5 % of CHPC. On a basis of the proposed method it can be concluded that all applied kinetic analysis methods give almost the same equivalent kinetic results.
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DSC, curing kinetics, compensation effect