Thermal and spectral studies on cellulose arylphosphinites in air

Abstract

The thermal behaviour of cellulose and cellulose arylphosphinite samples have been studied using DTA, TG and DTG techniques from ambient temperature to 700°C in dynamic air atmosphere. First exotherms in DTA curves of cellulose arylphosphinite samples attributable to the decomposition process have been found to be lower than that of cellulose. Various kinetic and thermodynamic parameters have been obtained from TG curves using Broido method and transition state theory. For the decomposition stage of cellulose arylphosphinite samples the values of the activation energies are found to be in the range 83-138 kJ mol^-1 and are lower than that of cellulose (187 kJ mol^-1). The EPR signals have given indication of the formation of trapped and stable free radicals in the thermal degradation of cellulose and cellulose arylphosphinite samples. Higher char yields of cellulose arylphosphinite samples as compared to cellulose lead to the conclusion that cellulose arylphosphinites are good flame retardants. A flame-retardancy mechanism for the thermal degradation of cellulose arylphosphinites has been proposed.