Archivio Istituzionale della RicercaMixtures of epoxy resins in the presence of epoxy hyperbranched polymers (HBP), in the range of 5-15 wt%, were investigated in the cationic photocuring process. No significant differences in rate of polymerization or final epoxy groups conversion were observed. At low concentration, HBP acts as plasticizer and causes a decrease of the glass transition temperature of the epoxy matrix and of the E' value. At higher concentration (about 15 wt%), two Tg values are evident, indicating a biphasic structure of the system. The SEM analysis of the fracture surface of the samples confirms a particulate structure with separate HBP domains interconnected to the epoxy matrix. In all the samples investigated, a clear increase of the impact resistance was observed, resulting either from the plasticization effect or from the particulate structure induced by the presence of the HBP resin.
Hyperbranched polymers in cationic photopolymerization of epoxy systems / Sangermano, Marco; Malucelli, Giulio; Bongiovanni, Roberta Maria; Priola, Aldo; A., Harden; N., Rehnberg. - In: POLYMER ENGINEERING AND SCIENCE. - ISSN 0032-3888. - 43:8(2003), pp. 1460-1465. [10.1002/pen.10123]
Hyperbranched polymers in cationic photopolymerization of epoxy systems
SANGERMANO, MARCO;MALUCELLI, Giulio;BONGIOVANNI, Roberta Maria;PRIOLA, ALDO;
2003
Abstract
Mixtures of epoxy resins in the presence of epoxy hyperbranched polymers (HBP), in the range of 5-15 wt%, were investigated in the cationic photocuring process. No significant differences in rate of polymerization or final epoxy groups conversion were observed. At low concentration, HBP acts as plasticizer and causes a decrease of the glass transition temperature of the epoxy matrix and of the E' value. At higher concentration (about 15 wt%), two Tg values are evident, indicating a biphasic structure of the system. The SEM analysis of the fracture surface of the samples confirms a particulate structure with separate HBP domains interconnected to the epoxy matrix. In all the samples investigated, a clear increase of the impact resistance was observed, resulting either from the plasticization effect or from the particulate structure induced by the presence of the HBP resin.
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https://hdl.handle.net/11583/1404391
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