Thermal Degradation of Polyurethane Elastomers: Determination of Kinetic Parameters

Abstract

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 0 diphenylmethan diisocyanate (MDI) and 4,4 0 -dicyclohexylmethane diisocyanate (H 12 MDI) 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.

Influence of synthesis temperature on thermal properties of thermoplastic polyurethane prepared by torque rheometer

“…The residual mass was not considered for the conversion determination. The E a values obtained in this work were consistent with the literature [32, 35].…”

“…The TPU obtained at 80°C not clearly shows the rigid‐to‐rubber decomposition transition probably because of its higher degree of phase mixing, as observed by TGA results. The change in decomposition of the rigid phase (first stage of decomposition [32, 33]) to rubber phase is close to α = 0.25. Although the theoretical rigid phase content of the synthesized TPUs is ∼45% wt (determined as the content of MDI and BDO, related to the total mass of polymer [34]), it was expected that the transition of the rigid to rubber phase decomposition occurs at lower fraction than 0.45 due the presence of aromatic rings in the rigid phase, what contributes to the residual mass.…”

Novel Polyurethane Gels: The Effect of Structure on Gelation

“…Thermal degradation behaviour of PU is bimodal and low temperature degradation corresponds to the decomposition of hard segments and second step degradation is due to the decomposition of soft segments. [20,21] As the rigidity of the chain extender increases from BD to BP or HEBP, maintaining the hard segment content constant, then PU chains become stiffer, as a result thermal decomposition temperature increases. On the contrary, the solvent rentention power decreases with the rigidity of the chain extenders.…”

Kinetic Parameters Estimation for Thermal Degradation of Polyurethane Elastomers

“…The initial degradation in stage I results primarily from the decomposition of the urethane segment, while stage II proceeds by the depolycondensation and polyol degradation mechanisms and is affected by the SS content [3,4]. In this work we have extended previous studies on kinetics of thermal degradation of PU elastomers [2], with parameter estimation and confidence interval computation of kinetic parameters associated with the degradation processes. …”

“…The weight-loss kinetics at elevated temperatures is the simplest and most accurate way to study the thermal degradation. In a previous article [2], we reported the thermal degradation model of segmented PU elastomers before and after UV irradiation. The thermal degradation model of prepared PU elastomers was characterized as a two-step decomposition process (see Figure 1).…”