Microencapsulation of ammonium polyphosphate with PVA-melamine-formaldehyde resin and its flame retardance in polypropylene

With a shell of PVA-melamine-formaldehyde resin, microencapsulated ammonium polyphosphate (VMFAPP) is prepared by in situ polymerization and characterized by FTIR and XPS. Microencapsulation gives VMFAPP better water resistance and flame retardance compared with APP in PP. Thermal stability and fire resistance behavior have been analyzed and compared. The LOI value of the PP/VMFAPP composite is higher than that of the PPAPP composite. The UL 94 ratings of most of the PP/VMFAPP composites are V-0, whereas PPAPP gives no rating at the 30% additive level. The water resistant properties of the PP composites are studied. Results of the cone calorimeter experiment show that VMFAPP is an effective flame retardant in PP compared with APP. The thermal degradation behaviors of APP and VMFAPP have been studied using TG and dynamic FTIR. Copyright (C) 2008 John Wiley & Sons, Ltd.