Influence of temperature and BN nanoparticles on UV, thermal and dark curing of a cycloaliphatic epoxy resin

Autor:	Margarita González Prolongo, Carmen Arribas Arribas, A. González-González, Silvia G. Prolongo
Rok vydání:	2020
Předmět:	Materials science Cationic polymerization 02 engineering and technology Epoxy Dynamic mechanical analysis 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences 010406 physical chemistry 0104 chemical sciences chemistry.chemical_compound Photopolymer chemistry Chemical engineering Boron nitride visual_art visual_art.visual_art_medium UV curing Physical and Theoretical Chemistry 0210 nano-technology Photoinitiator Curing (chemistry)
Zdroj:	Journal of Thermal Analysis and Calorimetry. 142:617-627
ISSN:	1588-2926 1388-6150
DOI:	10.1007/s10973-020-09441-0
Popis:	The influence of boron nitride (BN) nanoparticles on cationic photopolymerization of an epoxy resin at different temperatures was investigated employing photo-DSC. A difunctional cycloaliphatic epoxy resin was polymerized in the presence of triarylsulfonium hexafluoroantimonate salts (cationic photoinitiator). BN-epoxy dispersions containing 5 mass% of BN were obtained by sonication. The epoxy conversion during UV irradiation was determined at seven temperatures, from 30 to 90 °C. The conversion reached was strongly dependent on temperature, and lower conversions were obtained in the presence of BN. After the UV curing, the samples were thermally postcured by dynamic heating in the DSC. The thermal postcuring shows two exothermal peaks, being the main one dependent on the temperature of the previous UV curing and on the composition. The total achieved conversion (65–77%) is lower for the samples containing BN compared to neat epoxy. The UV-irradiated samples at 40 °C reached conversions between 24 and 36%; afterward, they were kept under isothermal dark curing (40 °C) up to 1 month leading to significant conversion increases, independently of the composition and reaching a final conversion between 60 and 70%. DMTA measurements of dark-cured specimens evidence a heterogeneous epoxy matrix, thus needing higher postcuring temperatures to get homogeneity. The Tg of the epoxy matrix is reduced in the presence of BN nanoparticles.
Databáze:	OpenAIRE
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