Enhance the interaction between ammonium polyphosphate and epoxy resin matrix through hydrophobic modification with cationic latex

The aim of this study is to improve the interaction between ammonium polyphosphate (APP) and epoxy resin (EP) matrix. The modified ammonium polyphosphate (MAPP) with hydrophobic property was prepared by the cationic latex via electrostatic interaction. The results showed that the hydrophobicity and thermal stability of MAPP were improved over APP. The increased hydrophobicity of MAPP facilitated its mixing efficiency with EP matrix and the mechanic property results of EP/MAPP composites supported an enhancement of interfacial interaction between MAPP and EP matrix. For example, the impact strength of EP/MAPP13.5 (13.5 wt part of APP per hundred EP matrix) was 15.58 kJ m −2 , compared with 12.47 kJ m −2 of EP/APP13.5, while the tensile strength increased from 51.06 MPa of EP/APP13.5 to 61.76 MPa of EP/MAPP13.5. Such interfacial interaction improvement would assist the stress transfer and adsorption of impact energy. In addition, the MAPP showed little impact on the flame resistance properties of APP. For example, both EP/APP13.5 and EP/MAPP13.5 composites had V-0 grade in the vertical burning tests.