Degradation modelling polyesters

A particular polyester network may be considered as a model of degraded ideal polyester based on a prepolymer having an infinite molar mass with a number of chain scissions equal to Ave = b/2. Thus, polyester samples differing by the initial prepolymer molar mass can be used to calibrate rubber-elasticity measurements. 

Walter, T., Augusta, J., Muller, R.-J., Widdecke, H., and Klein, J., 1995, Enzymatic degradation of a model polyester by lipase from Rhizopus delemar. Etcym. Microb. Technol 17 218-224. 

Polyesters are important thermoplastic resins, which can be obtained by the condensation reaction of glycols and acids or anhydrides 798163. For example, the condensation polymerisation of ethylene glycol or butylene glycol and terephthalic acid produces the well-known polyesters, poly(ethylene terephthalate) (PET) or poly(butylene terephthalate) (PBT), respectively. The mechanism of thermal degradation of polyesters has been studied for many years 817822 776328 756176 670828 with the help of model compounds. However, there is still some current controversy on the crucial point whether the primary thermal decomposition reactions that occur in polyesters involve radical or ionic processes 777330 490068. ... 

Han, X., Pan, J., 2011. Polymer chain scission, oligomer production and diffusion a two-scale model for degradation of bioresorbable polyesters. Acta Biomaterialia 538—547. 

Kinetic studies have been made on the thermal decomposition of a poly(oxypropylene)triol-toluene di-isocyanate copolymer foam. Following a diffusion rate-controlled step, the cellular structure collapses to a viscous liquid and degradation then occurs on a random scission basis. Products of degradation of A-monosubstituted and A A-disubstituted polyurethanes have been analysed by direct pyrolysis in the ion source of a mass spectrometer. The mono-substituted polymers depolymerize quantitatively to di-isocyanates and diols, whereas the disubstituted materials decompose selectively to secondary amines, olefins, and carbon dioxide. The behaviour of the monosubstituted polymers has been confirmed in an i.r. study of the degradation of model compounds. A study of the thermal degradation in vacuum of polyurethanes prepared from butanediol, methylene bis(4-phenylisocyanate), and hexanedioic acid-ethylene glycol-propylene glycol polyesters has been reported and reaction mechanisms proposed. ... 

Antheunis, FI., van Der Meer, J.C., de Geus, M., Kingma, W., Koning, C.E., 2009. Improved mathematical model for the hydrolytic degradation of aliphatic polyesters. Macromolecules 42, 2462-2471. 

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