Biodegradation of aliphatic polyesters

Synthetic polymers appeared about sixty years ago and medical people realized immediately that this new class of materials was of interest for therapeutic applications. For example, isotonic aqueous solutions of polyvinylpyrrolidone (PVP) were used as plasma expander during World War II and although this compound was far from ideal, it stayed in use for years before substitutes appeared [I]. Since then, many polymers have been 

Degradable Polymers. Edited by Gerald Scott and Dan Gilead. 

Before discussing the various aspects of the biodegradation of aliphatic polyesters, let us first make a few semantic comments. 

Recently at the Second International Scientific Workshop on Biodegradable Polymers and Plastics (Montpellier, France), a majority of participants agreed with the following series of definitions [19]  

Ring-opening polymerization generally yields high molecular weight (MW) polymers, whereas direct polycondensation leads to low MW products. 

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In 2002, Lee et al. [51] reported the biodegradation of aliphatic polyester-based nanocomposites under compost. Figure 9.13(A, B) represent the clay content dependence of biodegradation of APES-based nanocomposites prepared with two different types of MMT clays. They assumed that the retardation of biodegradation was due to the improvement of the barrier properties of the aliphatic APSE after nanocomposite preparation with clay. However, there are no data about permeability. 

Li S, Vert M (1995) Biodegradation of aliphatic polyesters. In Scott G, Gilead D (eds), Degradable polymers. Chapman 8c Hall, London, chap 4, p 43... 

Li, S, and M. Vert. 1995. Biodegradation of aliphatic polyesters. In Degradable polymers Principles and applications, eds. G. Scott and D. Gilead, 44. New York, NY Chapman and Hall. 

For conventional technical applications aromatic polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) are widely used. But these polymers are biologically inert and thus not directly applicable as biodegradable plastics. Combining both the excellent material properties of aromatic polyesters and the potential biodegradability of aliphatic polyesters has led to the development of a number of commercially available aliphatic-aromatic co-polyesters over the last decade or so. 

Mochizuki, M. Hirami, M. Structural effects on biodegradation of aliphatic polyesters. Polym. Adv. Technol. 1997, 8 (4), 203. 

With the attempt to combine good material properties of aromatic polyesters and biodegradability of aliphatic polyesters, aliphatic aromatic copolyesters have been developed during the last years to be used as technical biodegradable plastics The BASF AG / Germany is now producing a biodegradable material based on a copolyester of 1,4-butanediol, adipic acid and terephthalic acid (BTA-copolyester) tmder the trade name Ecoflex in a several thousand tons per year scale. 

Teramoto, N., Urata, K., Ozawa, K. and Shibata, M. (2004) Biodegradation of aliphatic polyester composites reinforced by abaca fiber. Polymer Degradation and Stability, 86,401-409. 

Zhu, C., Zhang, Z., Liu, Q. et al. (2003) Synthesis and biodegradation of aliphatic polyesters from dicarboxylic acids and diols. Journal of Applied Polymer Science, 90 (4), 982-990. 

Table 8 Weight-loss WL) biodegradabilities and biological oxygen demand BOD) biodegradabilities of aliphatic polyester films in different natural waters for 28 days at 25°C (Kasuya et al. 1998)... 

Mochizuki M, Hirami M (1997) Structural effects on the biodegradation of aliphatic polyesters. Polym Adv Technol 8 203-209... 

Le Digabel F, Boquillon N, Dole P et al (2004) Properties of thermoplastic composites based on wheat-straw lignocellulosic fillers. J Appl Polym Sci 93 428-436 Lee S -R, Park FI-M, Lim H et al (2002) Microstructuie, tensile properties, and biodegradability of aliphatic polyester/clay nanocomposites. Polymer 43 2495-2500 Lee SFI, Ohkita T, Kitagawa K (20(M) Eco-composite from poly(lactic acid) and bamboo fiber. Flolzforschung 58 529-536... 

Suzuki, T. and Tokiwa, Y. (1986) Biodegradability of Aliphatic Polyesters. Apic. Biol Chetn., 50(5), 1323. 

S. M. Li, M. Vert, Biodegradation of aliphatic polyesters, in G. Scott (Ed.), Biodegradable Polymers Principles and Applications, 2nd edition, Kluwer Academic Pubhshers, Dordrecht, 2002, pp. V/71 ff... 

While the biological susceptibility of maity aliphatic polyesters has been known for maiy years, aromatic polyesters such as polyetltylene terephthalate (PET) or polybutylene tereph-thalate are regarded as non-biodegradable [39]. To improve the use properties of aliphatic polyesters, an attempt was made to combine the biodegradability of aliphatic polyesters with the good material performance of aromatic polyesters in novel aliphatic-aromatic copolyesters. 

In order to try to combine both the excellent material properties of aromatic polyesters and the potential biodegradability of aliphatic polyesters, several aliphatic-aromatic copolyesters have been developed over the last 20 years and are now, together with the aliphatic polyester polylactic acid (PEA), one of the most common biodegradable resins on the market with a production of several thousand tonnes per year. The... 

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