Curing kinetics of divinyl ester resins with styrene

✍ Scribed by María L. Auad; Mirta I. Aranguren; Guillermo Eliçabe; Julio Borrajo

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 185 KB
• Volume: 74
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19991031)74:5<1044::aid-app2>3.0.co;2-q

✦ Synopsis

The curing reaction of a divinyl ester resin with different proportions of styrene-4, 20, and 40% by weight-was investigated by differential scanning calorimetry (DSC) using isothermal and dynamic modes. The different constraints on the reaction rate was globally considered, taken the reaction as divided in two regimens: below the vitrification regimen and during the vitrification regimen. Below the vitrification regimen, the autocatalytic model developed by Kamal was used to perform the analysis of the curing kinetics of divinyl ester resin with styrene. Experimental data from dynamic and isothermic runs, at a fixed composition, were simultaneously considered, while the actual temperature records (measured during the DSC runs) were also taken into account. The adjusted kinetic parameters took into account the gel effect on the radicals' termination rate and the structure constraints on the reactivity of pendant vinyls groups, present during this stage. During the vitrification stage, the diffusion control due to the low mobility of the reactive groups and molecules was incorporated into the overall rate constant according to the Rabinowitch model, which considers the two regimen contributions to the overall reaction rate kinetic. The Vogel-Fulcher relationship was adopted to express the temperature dependence of the rate constant during the vitrification stage. The method presented here has been satisfactorily applied to dynamic and isothermal curing reactions, allowing a simple and general kinetic expression useful in the design, optimization, and control of the processing of composites based on these thermoset polymers to be obtained.