Novel epoxy-benzoxazine water-based emulsions with reactive benzoxazine surfactants for coatings

Autor: M. Krajnc, R. Ambrozic, U. Sebenik
Jazyk: angličtina
Rok vydání: 2014
Předmět:
Zdroj: eXPRESS Polymer Letters, Vol 8, Iss 8, Pp 574-587 (2014)
Druh dokumentu: article
ISSN: 1788-618X
DOI: 10.3144/expresspolymlett.2014.61
Popis: Novel epoxy-benzoxazine emulsions designed for water-based coatings were prepared and investigated. Bisphenol A-based epoxy resins with molar weights of 340, 377 and 1750 g/mol along with epoxidized soybean oil were emulsified using mono- and bi-functional benzoxazine surfactants, which are able to react with epoxy resins at their cure temperature. The structure of synthesized surfactants carrying one or two polyether chains was confirmed using Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance and differential scanning calorimetry. Stability of emulsions was verified by particle diameters measurements. Coatings, made directly from emulsions, were dried and cured at elevated temperature using 3,3'-dimetoxybenzidine as curing agent to ensure a highly cross-linked structure of thermosetting films. Curing process, thermal properties and hardness of cured films were investigated. It was found that benzoxazine molecules were well incorporated into the epoxy network upon curing, which ensures no void structure of cured copolymer and enhanced coating properties.
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