Degradation of Polyesters

Figure 10.3 General mechanisms for degradation of polyester in acid and basic solutions.

The color of the polymer can also be affected by inappropriate reaction conditions in the polymerization process, such as temperature, residence time, deposits of degraded polymer or the presence of oxygen. Degradation of polyesters and the generation of chromophores are thermally effected [29b, 29c, 39], The mechanism of thermal decomposition is based on the pyrolysis of esters and the formation of unsaturated compounds, which can then polymerize into colored products. It can be assumed that the discoloration takes place via polymerization of the vinyl ester end groups or by further reaction of AA to polyene aldehydes. 

Extensive degradation of polyester based thermoplastic polyurethane samples occurs due to hydrolysis In the presence of water and transesterification In the presence of methanol. 

Fields RD, Rodriguez F (1976) Microbial degradation of polyesters. In Sharpley JM, Kaplan AM (eds) Proc 3rd Int Biodegradation Symp. Applied Science, Barking, England, pp 775-784... 

Takamoto, T., Uyama, H., and Kobayashi, S. (2001) Lipase-catalyzed degradation of polyester in supercritical carbon dioxide. Macromol. Biosci., 1 (5), 215-218. 

The highest rate of degradation of polyester (i) is observed between 500 and 550°C. Differential thermal analysis indicates that decomposition occurs around 465°C. CO and C02 are the major products formed in this... 

Pitt, C., Non-microbial degradation of polyesters mechanisms and modifications, in Proceedings of the Second International Scientific Workshop on Biodegradable Polymers and Plastics, Vert M., Feijen J., Albertsson A., Scott G. and Chiellini E., Eds., Royal Society of Chemistry, Cambridge, UK, 1992, page 7. 

Lovett, D. and Eastop, D. (2004). The degradation of polyester polyurethane prehminary study of 1960s foam-laminated dresses. In Preprints of IIC Congress Modem Art, New Museums Bilbao, 13-17 September 2004 (A. Roy and P. Smith, eds) pp. 100-104, IIC. 

Luderwald, I., Thermal degradation of polyesters in the mass spectrometer. Developments in Polymer degradation, Vol. 2, Grassie, N., Ed. Applied Science Publisher, London, 1979. 

Okada, M., Tsunoda, K., Tachikawa, K. and Aoi, K. (2000) Biodegradable polymers based on renewable resources. IV. Enzymatic degradation of polyesters composed of 1,4 3,6-dianhydro-D-glucitol and aliphatic dicarboxylic acid moieties. Journal of Applied Polymer Science, T1 (2), 338-346. 

In recent years, biodegradable plastics have attracted as environmentally fHendly materials to solve the problem of the waste plastics. This paper reports the microbial degradation of polyesters in the naarine environments and the properties of extracellular depolymerases from some polyester-degrading microorganisms. 

Many other companies have patented additives which they claim to be useful in preventing thermal degradation of polyesters, and are discussed helow. 

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