Thermal degradation kinetics of polyurethane-siloxane anionomers

A series of polyurethane-siloxane anionomers (PU-PDMS), synthesised from isophorone diisocyanate (IPDI), poly(oxytetramethylene)diol (PTMO), polydimethylsiloxane-diol (PDMS), 2,2-bis(hydroxymethyl)propionic acid (DMPA), ethylenediamine (EDA), and triethylamine (TEA), have been submitted to thermal stability investigations under inert or oxidizing atmosphere. The polymers had different amounts of dimethylsiloxane units in their elastic segments (0-15 wt.%). It was observed that siloxanes influenced thermal stability of PU-PDMS anionomers mainly at the second step of degradation. The kinetic degradation studies by Ozawa-Flynn-Wall and Friedman methods revealed that the activation energy (E-a) and pre-exponential factor (A) increased as a result of siloxane introduction into PU anionomers. The best approximation of the f(alpha) function was found for the D2 Cn models. (C) 2010 Elsevier B.V. All rights reserved.