Polymer degradation. II. Mechanism of thermal degradation of polyoxypropylene glycol–toluene 2,4‐diisocyanate polymer (POPG–TDI) and a block polyether glycol–TDI polymer

Abstract

synopsisFurther studies on the thermal degradation of POPG-TDI polymer have been carried out. It has been shown that at temperatures of -2OO0C., the predominant degradation process involves random scission of the urethane linkages to give substantial amounts of isocyanate and hydroxyl. Kinetic data suggests that the weakest links in POPG-TDI polymer are spaced a t intervals of -10,000 in molecular weight and that they may be eliminated by pretreatment of the POPG with ethylene oxide to form a block COpolyether which is used to prepare the polyurethane. At temperatures exceeding 250°C. and a greater conversion to volatile fragments (>lo%) the kinetics of degradation of POPG-TDI are similar to results for POPG and indicate scission of the polyether bonds by a combination of intramolecular proton abstraction and free radical unzipping reactions, in agreement with previous studies of POPG of much higher molecular weight.

Confined‐Volume Effect on the Thermal Properties of Encapsulated Phase Change Materials for Thermal Energy Storage

“…In agreement with previous studies on PU, the first step of capsule decomposition corresponds to the breakage of the polyurethane shell, followed by decomposition of the soft segment of the PU shell and the decomposition of encapsulated docosane as a consequence of its release. The second step corresponds to the decomposition of the hard segment of the PU shell.…”

New Polyurethane/Docosane Microcapsules as Phase‐Change Materials for Thermal Energy Storage

“…According to previous studies20, 21 on thermal decomposition and degradation of PU, the first step corresponds to the breakage of the polyurethane shell, decomposition of the soft segment (PEG1000) of the PU shell, and the decomposition of the n ‐docosane as a consequence of its release. The second step corresponds to the decomposition of the hard segment (MDI) of both the PU and PUshell/docosane 22.…”

Heat release and structural collapse of flexible polyurethane foam

“…The decomposition of the urethane and urea bonds leads to the breakdown of the network structure and a transition of the foam to a low viscous liquid [3,18]. This liquid was reported to be a polyol for a commercial flexible foam [14], or to consist of the recovered diol [19] or a similar substance for linear polyurethanes [20].…”