Micro encapsulated ammonium polyphosphate with urea-melamine-formaldehyde shell: preparation, characterization, and its flame retardance in polypropylene

Microencapsulated ammonium polyphosphate (MCU-APP) with urea-melamine-formaldehyde (UMF) resin is prepared by in situ polymerization, and is characterized by FTIR and XPS. The microencapsulation of APP with the UMF resin leads to a decrease in the particle's water solubility. The flame retardant actions of MCU-APP and APP in PP are studied using limiting oxygen index (LOT) and UL-94 test, and their thermal stability is evaluated by thermogravimetric analysis. It is found that the LOT value of the PP/MCU-APP composite is higher than the value of the PP/APP composite. In comparison with the PP/MCU-APP composites, the LOT values of the PP/MCU-APP/DPER ternary composites at the same additive loading increase, and UL-94 ratings of most ternary composites are raised to V-0. The water-resistant properties of the PP composites containing APP and MCU-APP are studied. Moreover, the combustion behavior of the PP composites is investigated by the cone calorimeter. Copyright (C) 2008 John Wiley & Sons, Ltd.