Incorporation of red phosphorous into poly(ethylene terephthalate) (PET) confers good fire retardancy. However, the initial rates and levels of smoke emission of these red phosphorous filled PET samples increase dramatically with increasing loading of phosphous. In order to overcome these limitations, metallic oxides such as magnesium oxides, aluminum oxide and antimony trioxide are used to replace part of the phosphorous. The smoke suppressant properties of these samples were found to improve significantly as the amounts of metallic oxides increased. In fact, some of the samples exhibit ‘synergetic’ fire retardancy as the amounts of magnesium or aluminum oxides reach the ‘optimum’ value. In addition, the magnesium oxide samples always exhibit better fire retardancy and smoke suppressant properties than aluminum oxide and antimony trioxide samples. In order to understand these interesting behaviors, thermogravimetic analysis, limiting N2O index, and surface temperature analysis during combustion were investigated. Possible mechanisms accounting for these behaviors are discussed.
Polymer Degradation and Stability 61(3), pp.399-407