Biodegradable aliphatic-aromatic polyesters

Ecoflex A Completely Biodegradable Aliphatic-Aromatic Polyester. 104... 

Yamamoto M, Witt U, Skupin G, Beimbom D, Muller RJ (2002) Biodegradable aliphatic-aromatic polyesters Ecoflex. In Doi Y, Steinbiichel A (eds) Biopolymers, vol 4. Wiley-VCH, Weinheim, p 11... 

Biodegradable aliphatic-aromatic polyesters obtained from dicarboxylic acids and dialcohols are known in the literature and are com-... 

C. Bastioli, T. Milizia, G. Floridi, A.S. Lallaro, G. Celia, and M. Tosin, Biodegradable aliphatic-aromatic polyesters, US Patent 8193 298, assigned to Novamont S.p.A. (Novara, IT), June 5, 2012. 

Table 7.4 Properties of Three Biodegradable Aliphatic-Aromatic Polyesters...

Yamamoto, M., Witt, U., Skupin, G., Dieter, B.D. and Muller, R.-J. (2003) Biodegradable Aliphatic-Aromatic Polyesters Ecoflex , Biopolymers, Institute of Microbiology, University of Munster, Alexander Steinbiichel. 

Yamamoto, M., U. Witt, G. Skupin, D. Beimbom, and RJ. Muller, Biodegradable Aliphatic-Aromatic Polyesters Ecoflex Chapter 11 in Doi Y, A. Steinbuchel (Eds.) Biopolymers, Vol. 4, Wiley-VCH Verlag GmbH, Weinheim, Germany, pp.299-314 (2002)... 

The price of synthetic biodegradable polymers has come down a little during the last three years. In 2003, for example, the average price of Eastar Bio and BASF s Ecoflex was around 3.5-4.0 per kg. In 2005, the average cost of an aliphatic aromatic polyester biopolymer was between 2.75-3.65 per kg. The more specialised polymers, such as DuPont s Biomax, cost as much as 5-6 per kg. Polycaprolactones cost between 4-7 per kg. Synthetic biodegradable polymer prices are expected to fall further over time as production volumes increase and unit costs fall further. 

In 1977, Tokiwa and Suzuki reported that some lipases, which are extracellular enzymes that usually cleave esters in oils and fats, are also able to attack ester bonds in some aliphatic polyesters and can depolymerize such materials [38]. Aliphatic polyesters, however, exhibit only limited useful properties for many applications. Aromatic polyesters, such as PET and PBT, which are widely applied because of their excellent properties, are not attacked by hydrolytic enzymes. This led to the development of aliphatic-aromatic polyesters as biodegradable plastics that present a compromise between biodegradability and material properties [39]. Recently, however, Muller et al. [40] have isolated a hydrolase (TfH) from Thermofibida fusca which is able to depolymerize the aromatic polyester PET at a high rate in contrast to other hydrolases such as lipases. They have demonstrated for the first time that commercial PET can be effectively hydrolyzed by an enzyme at a rate that does not exclude a biological recycling of PET. The effective depolymerization of PET with the enzyme TfH will result in water... 

To improve processability, mechanical properties and moisture resistance while maintaining biodegradability, starch may be mixed with aliphatic or aliphatic-aromatic polyesters, such as polycaprolactone (PCL), polylactic acid (PLA) and poly(butylene adipate-co-terephthalate) (PBAT), suffering complexing with these pol)miers [33,35]. 

To this group belong the aliphatic (i. e., non-aromatic) and the aliphatic-aromatic polyesters, described below. PCL can also be biodegraded directly by enz)rmes produced by microorganisms, without the initial stage of hydrolysis [24]. 

Muller R-J (2005) Aliphatic-aromatic polyester. In Bastioli C, editor. Handbook of biodegradable pol)rmers. UK Rapra Technology, pp. 303-337. 

Blending of starch with aliphatic polyesters improves their processability and biodegradability Particularly suitable polyesters are poly(s caprolactone) and its copolymers, or polymers of higher melting point formed by the reaction of 1,4-butandiol with succinic acid or with sebacic acid, azelaic acid, or polydactic acid), poly(hydroxyalkanoates), and aliphatic-aromatic polyesters. 

Witt U, Muller R-J, Deckwer W-D (1997) Biodegradation behaviour and material properties of aliphatic/aromatic polyesters of commercial importance. J Environ Polym Degrad 5 81-89... 

Novamont has recently patented polymeric compositions comprising biodegradable polyalkylenefuranoates, aliphatic/aromatic polyesters, and starch in destructurised, gelatinised or filler form [102]. 

The biodegradable materials obtainable from starch modified with aliphatic or aliphatic/aromatic polyesters, discussed in Section 6.1.6, proved to be particularly suitable for the production of shopping bags and are today leading this sector. 

Based upon the Chapter Aliphatic-Aromatic Polyesters by Rolf-Joachim Muller in the Handbook of Biodegradable Polymers, Rapra Technology Limited, Shawbury, UK, 2005. 

In the biodegradable BTA aliphatic-aromatic polyesters available on the market, the amount of aromatic acid in the polymer chain was always maintained below 49 mol% in view of the significant and sudden decrease of the biodegradation of polyesters above this threshold. This behaviour was attributed to the lower biodegradability of the butyleneterephthalate sequences with length equal or higher than 3 which, above the said threshold, represent more than 10 % of the aromatic fraction of these polyesters [55] (Section 10.3.6). 

In recent years, Novamont developed a family of aliphatic-aromatic copolyesters with its aliphatic dicarboxylic acid component predominantly based on long chain dicarboxylic acids of natural origin (sebacic acid, azelaic acid and brassylic acid) [56-58]. Compared with aliphatic-aromatic polyesters where the aliphatic dicarboxylic component is a shorter carbon chain length, such as BTA polyesters, these copolyesters do not show the sudden decrease of biodegradation properties above... 

S. Basei in Influence of Starch on the Aerobic and Anaerobic Biodegradation of an Aliphatic and an Aliphatic-Aromatic Polyester, University of Venice, Italy, 1999. [Graduation thesis]... 

In contrast to most aliphatic polyesters, aromatic polyesters like PET provide excellent material properties [50]. To combine good material properties with biodegradability, aliphatic/aromatic copolyesters have been developed. Several major polyester producers in Europe and the United States have recently begun marketing aliphatic/aromatic copolyesters for biodegradable applications. BASF markets a product, Ecoflex , which is a copolyester of butanediol, adipic acid, and dimethyl terephthalate. Eastman s Eastar Bio Copolyester 14766 is a similar aliphatic/aromatic copolyester. DuPont markets a modified PET known as Biomax . 

The requirement, that all components of a plastic-composition must be degraded is of essential relevance for copolymers and especially for aliphatic-aromatic copolyesters. Here in one polymer chain structures are combined, which differ significantly in their degradation behaviour when the monomers are located in the corresponding homopolymers (aliphatic polyesters often are easily biodegraded while aromatic polyesters such as PET are quite biologically resistant). In this particular case it has to be ensured that no domains within the copolyester chains are poorly biodegradable and can accumulate in the nature. 

R.-J. Muller, Aliphatic-Aromatic Polyesters in Handbook of Biodegradable Polymers, ed. C. Bastioli, Rapra Technology Fimited, Shawbury, Shrewsbury, Shropshire, SY4 4NR, UK, 2005, p. 303. 

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