Polyesters polymer degradation modelling

Marten E, Muller RJ, Deckwer WD (2003) Studies on the enzymatic hydrolysis of polyester I. Low molecular mass model esters and aliphatic polyesters. Polym Degrad Stab 80 485-501... 

Depolymerisation is due to various reasons. The lack of biological accessibility seems to be determined predominantly by intramolecular interactions. The aromatic intermediates formed during polymer degradation are embedded in a different environment than aromatic oligomers in the model substances. Furthermore, the model esters were mostly OH-terminated, while during polyester hydrolysis COOH-endings of the oligomers will also probably occur. Both effects can cause the final hydrolysis and metabolisation of the aromatic copolyesters observed in the experiments by the individual microbial strain. 

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. ... 

---