Cinética de cura não-isotérmica de resinas epóxi/casca do ovo: uma alternativa de desenvolvimento de biocompósitos.

Abstract

Epoxy compounds based on diglycidyl ether bisphenol A/methyl tetrahydrophthalic anhydride/2,4,6-tris (dimethylaminomethyl) phenol (DGEBA/MTHPA/DEH 35) were produced adding different concentrations of synthetic catalyser DEH 35; structural components of eggshell were investigated as natural catalyser. Analyzes of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetry (TGA) were conducted in order to obtain related results to reactions and chemical interactions; thermal stability; curing kinetics and degradation kinetics. FTIR spectra provided evidences of curing and degradation reactions can be monitored by changing characteristic bands, corroborated results by DSC and TG thermograms. Using Beer-Lambert Law affords determining the degree of curing and phase transition, i.e., active centers production, gelation and vitrification. Kissinger, Friedman isoconversional, Autocatalytic Friedman and Málek models were used in the curing kinetics investigation, the kinetic parameters were determined from DSC scans, and Friedman models presented best fits. Degradation kinetics was investigated by TG applying Kissinger, Friedman, Coats-Redfern and Servant models; best fit was verified with Friedman model. Among used catalyzers, DEH 35 and eggshell membrane (M) rendered improved results. Reported results in this work provide reliable tools to control the curing and degradation processes of epoxy compounds, enabling their use in laboratory scales, i.e., scientific research, as well as industrial processes.