Polymer degradation polyesters

Edge, M., Wiles, R., Allen, N. S., McDonald, W. A. and Mortlock, S. V., Characterisation of the species responsible for yellowing in melt degraded aromatic polyesters - I. Yellowing of polyethylene terephthalate), Polym. Degrad. Stabil, 53, 141-151 (1996). 

Zimmerman, H Degradation and stabilisation of polyester in Developments in Polymer Degradation —5, Grassie, N. (Ed.), Applied Science Publishers, London, 1984, Ch. 3 79-119. 

Polyesters offer multiple options to meet the complex world of degradable polymers. All polyesters degrade eventually, with hydrolysis being the dominant mechanism. Degradation rates range from weeks for aliphatic polyesters (e.g. polyhydroxyalkanoates) to decades for aromatic polyesters (e.g. PET). Specific local environmental factors such as humidity, pH and temperature significantly influence the rate of degradation. 

Copolyesters (such as BIOMAX ) which combine aromatic esters with aliphatic esters or other polymer units (e.g. ethers and amides) provide the opportunity to adjust and control the degradation rates. These added degrees of freedom on polymer composition provide the opportunity to rebalance the polymer to more specifically match application performance in physical properties, while still maintaining the ability to adjust the copolyesters to complement the degradation of natural products for the production of methane or humic substances. Since application performance requirements and application specific environmental factors and degradation expectations vary broadly, copolyesters are, and will continue to be, an important class of degradable polyesters. 

Agarwal S (2010) Chemistry, chances and limitations of the radical ring-opening polymerization of cyclic ketene acetals for the synthesis of degradable polyesters. Polym Chem 1 953-954... 

From the results presented in this chapter we can conclude that it is feasible to prepare sugar-based polymers analogous to the more qualified technological polymers - polyamides, polyesters, polyurethanes - with an enhanced hydrophilicity and degradability. However, in most cases, the high costs associated with the preparation of the monomers restrict the application of these polymers to biomedical applications and other specialized fields. More readily available monomers and simpler polymerization processes have to be found if sugar-derived polymers should compete with petrochemical-based polymers that are used in domestic applications. 

Herzog K, Muller RJ, Deckwer WD (2006) Mechanism and kinetics of the enzymatic hydrolysis of polyester nanoparticles by lipases. Polym Degrad Stab 91 2486-2498... 

Several review articles on biodegradable polymers and polyesters have appeared in the literature [12-22]. Extensive studies have been carried out by Al-bertsson and coworkers developing biodegradable polymers such as polyesters, polyanhydrides, polycarbonates, etc., and relating the structure and properties of aliphatic polyesters prepared by ROP and polycondensation techniques. In the present paper, the current status of aliphatic polyesters and copolyesters (block, random, and star-shaped), their synthesis and characterization, properties, degradation, and applications are described. Emphasis is placed primarily on aliphatic polyesters derived by condensation of diols with dicarboxylic acids (or their derivatives) or by the ROP of cyclic monoesters. Polyesters derived from cyclic diesters or microbial polyesters are beyond the scope of this review. 

Manfredi, L. B., Rodriguez, E. S., Wladyka-Przybylak, M., and Vazquez, A. Thermal degradation and fire resistance of unsaturated polyester, modified acrylic resins and their composites with natural fibres, Polym. Degrad. Stabil. 2006, 91, 255-261. 

Kandola, B. K., Akonda, M. H., and Horrocks, A. R. Use of high-performance fibres and intumescents as char promoters in glass-reinforced polyester composites, Polym. Degrad. Stabil. 2005, 88, 123-129. 

Hazer, B., Torul, O., Borcakli, M., Lenz, R. W., Fuller, R. C., and Goodwin, S. D. 1998. Bacterial production of polyesters from free fatty acids obtained from natural oils by Pseudomonas oleovorans. J. Environ. Polym. Degrad., 6,109-113. 

Biodegradable polymers can also be made from mineral oil based resources such as the aliphatic-aromatic co-polyester types. Mixtures of synthetic degradable polyesters and pure plant starch, known as starch blends, are also well-established products on the market. 

C. McNeill and M. Bounekhel Thermal degradation studies of terephthalate polyesters 1. Poly(alkylene terephthalates), Polym. Degrad. Stab., 34, 187-204 (1991). 

Solid organophosphite antioxidant that provides color stability, reduces polymer degradation, and improves gas fading performance in many resins. It may be used in polyethylene, polypropylene, polystyrene, polyesters, elastomers, PVC and thermoplastics. 

In general, results from NMR analysis In all media Indicate that the polyester to MDI molar ratio remained roughly constant In aging media which contained water since the degraded polyester Is not extracted. In addition, more change occurred In the molar ratio of polyester to MDI In polymer A than In polymer B during aging. In Table II, the amount of methyl ester (detectable by NMR analysis) Is shown to Increase with methanol content In Isooctane solutions. This provides evidence that the extent of chain scission Is proportional to methanol content. 

Of finishes used outside, the polymers that can offer the best protection against acid deposition are those not containing acid-sensitive groups such as esters. Inclusion of acid resistant paint binders such as vinyls, urethane, and epoxies would produce acid resistance only if the other components are also acid resistant. Saponification of esters catalyzed by hydroxyls formed during corrosion of steel substrates may also degrade polyesters (7). 

Billingham, N. C., Henman, T. J. Holmes, P. A. (1987) Degradation and stabilisation of polyesters of biological and synthetic origin, in Grassie, N. (Ed.) Developments in Polymer Degradation - 7, London Elsevier Applied Science. 

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