Study on epoxy resin modified by hyperbranched polysiloxane containing active amino group and its properties

Abstract

A novel phosphorous/silicon hybrid containing active amino was synthesized by bisphenol F epoxy resin modified by 0-(2,5-Dihydroxyphenyl)−10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide (ODOPB) and hyperbranched polysiloxane (APTMS-HPSi). At first, APTMS-HPSi was synthesized by a simple reaction among aminoethylamino propyltrimethoxy silane (APTMS) and tripropylene glycol (TPG). ODOPB was used to modify bisphenol F epoxy resin. Then add different content of APTMS-HPSi to the phosphorus-containing modified epoxy resin (P-EP). Fourier Transform Infrared (FTIR) Spectroscopy was used to characterized the chemical structure of APTMS-HPSi. The effects of APTMS-HPSi content on key properties was systemically investigated. Results showed that the addition of APTMS-HPSi and ODOPB effectively improve the toughness and liquid oxygen compatibility. With the increase content of APTMS-HPSi, char yield and limited oxygen index (LOI) value of the cured resin increased, and the liquid oxygen sensitivity coefficient (IRS) decreased. The elongation at break was increased 45.32% by only 6wt% loading with APTMS-HPSi in epoxy resin, and at the same time the IRS of the modified resin was reduced from 7% to 0%. When the addition amount was 6wt%, the fracture elongation, impact strength and fracture toughness KIC were increased by 52.1%, 81.8% and 54.3% respectively. Therefore, adding phosphorus and hyperbranched polysiloxane to the resin can improve the liquid oxygen compatibility and toughness of the epoxy resin at the same time.