Influence of Microencapsulation on Combustion Behavior and Thermal Degradation of Intumescent Flame-Retarded Epoxy Composite

Microencapsulated ammonium polyphosphate (MEAPP) with a shell of epoxy resin (EP) is prepared by in situ polymerization, and characterized by FTIR and SEM. The results of FTIR and SEM show that APP is microencapsulated by a layer of EP. After microencapsulation, a great improvement in water resistance is observed from the experiment of water resistance. And then, MEAPP is incorporated into EP to obtain flame retarded EP (FREP). The flammability of FREP is studied by UL 94 and Limiting Oxygen Index (LOI) Tests, and their thermal stability is evaluated by thermogravimetric analysis (TGA). At the loading of 6 wt.%, EP/MEAPP and EP/APP composites both meet the request of UL 94 V-0 rating, though the LOI value of EP/MEAPP is a little lower than that of EP/APP. However, after water treatment (75 degrees C, 6 days), EP/MEAPP (6 wt.%) maintains the V-0 level in UL 94 test, while EP/APP does not pass any rating at the same loading. The thermal degradation behaviors of MEAPP in EP composite are also investigated by thermogravimetry-Fourier transform infrared spectra (TG-FTIR).