Thermal degradation of bis-phosphorus esters of isosorbide

Abstract

Flame retardants from renewable resources have gained a lot of attention due to the increased severity of the health and environmental concerns about some types of effective brominated flame retardants. To mitigate this issue, phosphorus-based flame retardants are one of the main choices. In this regard, four phosphorus esters derived from an industrially available glucose derivative, isosorbide, as starting material have been generated and subjected to thermal degradation. The four esters show variable degradation profiles with phosphates providing better char yield than the phosphonates and phosphinates, which are more thermally stable. The thermal stability of the compounds at constant temperature and variable times was monitored using Fourier transform infrared spectroscopy and thermogravimetric analysis. The studies suggest that the degradation is accompanied by the release of the corresponding phosphorus acid.