Biobased Aliphatic Polyesters with DOPO Substituents for Enhanced Flame Retardancy.

Linear aliphatic copolyesters consisting of the biobased diols ethylene glycol, 1,3-propane diol, and 1,4-butane diol, the biobased dicarboxylic acids succinic acid, adipic acid, and sebacic acid, and a 9,10-dihydro-9-oxa-10-phospha-phenanthren-10-oxide (DOPO)-containing diol or dicarboxylic acid are presented. Structural characteristics of the new copolyesters are studied by ¹H and ¹³C NMR spectroscopy. The influence of chemical composition on the property profile is examined evaluating glass transition temperature T_g, melting behavior, thermal degradation and combustion, mechanical and burning behavior. Incorporation of DOPO monomers suppresses crystallization and yields materials with reduced toughness except in case of sebacates. T_g rises with the content of DOPO monomer. Correlations between the number of methylene groups in the repeating unit and the thermogravimetric analysis degradation maximum, as well as the heat release capacity from pyrolysis combustion flow calorimeter reflect the systematic influence of chemical structure. Copolycondensation with DOPO monomers enhances the limiting oxygen index providing materials with improved overall value. [ABSTRACT FROM AUTHOR]