Thermal degradation of polyurethane elastomers: Determination of kinetic parameters

The objective of this study is determining the kinetic parameters of thermal degradation of polyurethane elastomers before and after UV irradiation. To determine the kinetic parameters of elastomeric polyurethane (PUR) decomposition the Freeman-Carroll method of calculation is applied. The effect of soft segment and hard segment type, soft segment molecular weight and hard segment content on the kinetic parameters of the degradation process were measured. Polyurethane elastomers were obtained from poly(oxytetramethylene) glycol, PTMO, of 1000 and 2000 molecular weight and polycaprolactone glycol of 1250 molecular weight (PCL), 4,4'diphenylmethan diisocyanate (MDI) and 4,4'-dicyclohexylmethane diisocyanate (H12MDI) and 1,4-butanediol as chain extender. The activation energy values obtained for PUR elastomers based on polyester soft segment were higher than those based on polyether soft segment. The PUR elastomers based on aromatic type of diisocyanate have lower activation energy values than those based on cycloaliphatic type of diisocyanate.