Biowaste chicken eggshell (ES) powder was applied as a potential cure modifier in epoxy/anhydride systems. Cure behaviour and kinetics of composites filled with very low content (0.1 wt% based on epoxy resin) of ES, calcium carbonate (CaCO3), and terpolymer-modified fillers, mES and mCaCO3, were discussed comparatively. Surface analysis was performed by X-ray photoelectron spectroscopy. Cure kinetics was investigated by differential (Friedman) and integral (Ozawa and Kissinger–Akahira–Sunose) isoconversional methods using dynamic differential scanning calorimetry (DSC) data. Overall, protein precursors naturally existing in the structure of pristine ES facilitated crosslinking of epoxy and hardener of anhydride with functional groups resulting from terpolymer attachment to CaCO3 particles. Accelerated/hindered cure was observed depending on the filler type and surface characteristics, as investigated via the autocatalytic/non-catalytic nature of reactions and comparison of activation energy values of four types of composites. An enhanced cure was identified for composites containing untreated ES, which could be inferred on account of the lower competitive cure of carboxyl groups in the terpolymer backbone with epoxy compared to peptide groups existing in microporous pristine ES. On the other hand, mCaCO3 revealed low values of activation energy compared to pristine CaCO3, but still of the same order as ground biowaste ES.
Biowaste Chicken Eggshell Powder as a Potential Cure Modifier for Epoxy/Anhydride: Competitiveness with Terpolymer-modified Calcium Carbonate at Low Loading Levels
PUGLIA, Debora;
2017
Abstract
Biowaste chicken eggshell (ES) powder was applied as a potential cure modifier in epoxy/anhydride systems. Cure behaviour and kinetics of composites filled with very low content (0.1 wt% based on epoxy resin) of ES, calcium carbonate (CaCO3), and terpolymer-modified fillers, mES and mCaCO3, were discussed comparatively. Surface analysis was performed by X-ray photoelectron spectroscopy. Cure kinetics was investigated by differential (Friedman) and integral (Ozawa and Kissinger–Akahira–Sunose) isoconversional methods using dynamic differential scanning calorimetry (DSC) data. Overall, protein precursors naturally existing in the structure of pristine ES facilitated crosslinking of epoxy and hardener of anhydride with functional groups resulting from terpolymer attachment to CaCO3 particles. Accelerated/hindered cure was observed depending on the filler type and surface characteristics, as investigated via the autocatalytic/non-catalytic nature of reactions and comparison of activation energy values of four types of composites. An enhanced cure was identified for composites containing untreated ES, which could be inferred on account of the lower competitive cure of carboxyl groups in the terpolymer backbone with epoxy compared to peptide groups existing in microporous pristine ES. On the other hand, mCaCO3 revealed low values of activation energy compared to pristine CaCO3, but still of the same order as ground biowaste ES.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
