The influence of montmorillonite content on the kinetics of curing of epoxy nanocomposites/Uticaj udela montmorilonita na kinetiku umrezavanja epoksidnih nanokompozita

The influence of different montmorillonite contents on the kinetics of curing of epoxy/Jeffamine D-230 systems was followed by differential scanning calorimetry (DSC). The curing of epoxy nanocomposites was performed using dynamic regime at three different heating rates: 5, 10 and 20 °C/min. Three isoconversion methods were applied: two integral (Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose methods) and one differential (Friedman method). The presence of montmorillonite (MMT) caused the beginning of curing at lower temperatures. The shape of the DSC curves changed with the addition of MMT, supporting the hypothesis of a change in the reaction mechanism. For hybrids with 3 and 5 wt.% of MMT, the Ea dependence is very similar to those found for the reference system (epoxy/Jeffamine D-230) for curing degrees less than 60%. The hybrid with 10 wt.% of MMT had a lower activation energy than the referent system without montmorillonite. Greater differences were observed in the second part of the reaction, where it is known that the curing process is more controlled by diffusion (α > 0.60). The Ea value increases at the end of the reaction (α → 1), which was observed for all systems, and was more pronounced in the presence of montmorillonite. Keywords: Epoxy * Montmorillonite * DSC * Curing kinetics * Isoconversional methods U ovom radu pracen je uticaj udela organski modifikovanog montmorilonita na kinetiku umrezavanja epoksid/amin sistema. Reakcija umrezavanja hibrida sa razlicitim udelom montmorilonita pracena je metodom diferencijalne skanirajuce kalorimetrije (DSC) programiranim zagrevanjem od 30 do 250 °C, sa tri razlicite brzine zagrevanja: 5, 10 i 20 °C/min. Modeli izokonverzije (dva integralna, Ozawa-Flynn-Wall i Kissinger-Akahira-Sunose, i jedan diferencijalni, Friedman) primenjeni su da se razjasni da li montmorilonit utice na mehanizam reakcije umrezavanja hibrida. Epoksidni hibrid sa 10 mas.% organski modifikovanog montmorilonita ima znacajno nize vrednosti energija aktivacije za definisane stepene reagovanja, cime je potvrden kataliticki efekat gline sa slojevitom strukturom kada je prisutna u reakcionoj smesi u dovoljnoj kolicini. Uticaj otezane difuzije pri kraju reakcije je izrazeniji u prisustvu montmorilonita, cime je pokazano da njegovo prisustvo utice na ceo mehanizam umrezavanja. Kljucne reci: epoksid; montmorilonit; DSC; kinetika umrezavanja; modeli izokonverzije. Dostupno na Internetu sa adrese casopisa: