Three metal oxides

Bi2O3

Sb2O3 and SnO2

in different amounts were added into the polypropylene (PP)/ammonium polyphosphate (APP)/and dipentaerythritol (DPER) to study their enhancing effects on the intumescent flame retardance (IFR).The flame retardance of the PP/IFR composites was tested by the oxygen index (OI).TG

TG-FTIR and SEM were used to study the decomposition processes of PP/APP/DPER

APP/DPER and single APP or DPER with Bi2O3.The results showed that Bi2O3

Sb2O3 and SnO2 could increase the OI of PP/APP/DPER

and maximum OI values were found with increasing the amounts of the metal oxides.TG showed that Bi2O3 inhibited degradation of the APP/DPER at high temperatures and increased the charring;TG-FTIR indicated that the existence of Bi2O3 changed the release of NH3 and phosphorous oxides in the degradation process.SEM showed that the 0.1 wt% Bi2O3 made the char of the PP/APP/DPER homogeneous.Adding 0.1 wt% Bi2O3 and 1 wt% nanoclay into the IFR PP

the value of OI could reach 28.3% with 20 wt% retardant; the UL-94 could reach V-0 with 25 wt% retardant.The mechanical properties of the IFR PP system also increased by adding retardant with 0.1 wt% Bi2O3 and 1 wt% nanoclay.