Optimization of the performance of epoxy intumescent fire-retardant coatings utilizing amino-polysiloxanes with varying compositions

The performance of epoxy intumescent fire-retardant coatings (IFRC) needs to be optimized to meet the requirements of different application scenarios. In this work, a series of amine-functionalized polysiloxanes (amino-polysiloxanes) with different molar ratios of side groups including methyl, phenyl and amino were synthesized by polycondensation and ring-opening polymerization as curing agents for epoxy resins to achieve this target. The structures of amino-polysiloxanes were well characterized by FTIR, 1H NMR and chemical titration. Amino-polysiloxanes with different compositions can effectively adjust the glass transition temperatures (Tg) of epoxy thermosets in the range of 40.7-71.4 degrees C as revealed by DSC. IFRC based on different aminopolysiloxanes exhibit different expansion ratio and fire resistance time. Epoxy intumescent fire-retardant coating IC1Ph with epoxy binder Tg of 46.0 degrees C exhibited the longest fire resistance time up to 63.4 min. SEM-EDS results showed that the carbon layer of IC1Ph has the smallest and homogenous pore size. UV and humidity exposure tests indicate that presence of phenyl in amine-polysiloxanes contributed to the durability of the IFRC. Aminepolysiloxanes with varying composition are conducive to optimize of the performance of epoxy intumescent fire-retardant coatings.