A novel phthalazinone-based epoxy resin

A new paper reports on novel epoxy resin with excellent rheological property and intrinsic flame retardancy.

With higher loadings of expandable graphite Image source: sbox - Pixabay (symbol image).

Phthalazinone is a critical structural factor for high-performance polymer material, which is achieved by polar structure and the structure characteristic of unsymmetrical and kink non-coplanar. In the present study, a novel phthalazinone-based epoxy (EEPZ) has been designed and synthesised.

The rheological behaviors, thermal stability and combustion behaviors of cured systems have been investigated by dynamic rheology, TGA, DMA, UL-94 vertical burning and cone calorimetry tests. It was found that the phthalazinone-based EEPZ epoxy resin had the lower melting viscosity within broader processing window and enhanced char forming ability for bisphenol A epoxy/4′4-diamino-diphenyl sulfone (E44/DDS) system. When combined with only 20 wt% EEPZ in the E44 system, the E44/20%EEPZ/DDS, passed the UL-94 V-0 rating.

Decreased heat realease

In the combustion test, the total heat release, total smoke production and peak of heat release rate were sharply respectively decreased by 44.7%, 24.3% and 44.6% in the case of E44/20%EEPZ/DDS compared with E44/DDS. The results of morphology characterisation chemical structure and component for residue char in EEPZ epoxy resin confirmed that the phthalazinone group can lead to form nitrogen-containing compact char layer during combustion. The combined technologies (TGA-FTIR, Py-GC/MS) was utilised to detect the pyrolysis process of the crosslinks system and the charring mechanism. Simultaneously, the tensile strength and tensile modulus of the composites were also improved.

The study has been published in Journal of Materials Science, Volume 56, 2021.

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