Benzoxazine resin can be copolymered with low-viscosity epoxy resin to create a processable system with superior thermal properties upon the cure. In this study the hygrothermal aging of Benzoxazine-Epoxy copolymers were investigated. The moisture sorption-desorption behaviors of the bisphenol A-based benzoxazine (BZ-a) copolymered with various bi-functional epoxies were studied by aging the specimens in water bath at: 50 oC, 70 oC and 90 oC. The effects of moisture on the change in the physical, thermal, and mechanical properties of the copolymer systems were investigated by thermogravametric and volumetric analysis, dynamic mechanical analyzer (DMA), and Fourier Transform Infrared Spectroscopy (FTIR), respectively. Results showed that the choice of epoxy affected the swelling, mass adsorption and viscoelastic response of the specimen during exposure. No direct correlation was observed between the Tgand the amount of absorbed water. The complete water desorption of the specimens was performed to investigate potential hydrolytic reaction of the Benzoxazine Epoxy copolymers using FTIR. The results show that pure Benzoxazine absorbs 2.20% less moisture than the epoxy amine system, and the Benzoxazine Epoxy copolymer systems absorbed 1.00% and 1.72% less moisture than the epoxy amine system as well, showing resistivity of Benzoxazine systems to moisture attack even when copolymerized with epoxies.

Moisture adsorption of the benzoxazine-based thermoset matrix for advanced composite applications

2019 Spring National Meeting

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