Biodegradable aliphatic copolyesters

Pepic, D., M.S. Nikolic, and J. Djonlagic, Synthesis and characterization of biodegradable aliphatic copolyesters with polyftetramethylene oxide) soft segments. Journal of Applied Polymer Science, 106(3) p. 1777. 2007. 

At the end of the 1990s, BASF commercialized Ecoflex F, a completely biodegradable statistical copolyester based on the fossil monomers 1,4-butanediol (BDO), adipic acid and terephthalic acid (see Fig. 3). Ecoflex F combines the good biodegradability known from aliphatic polyesters with the good mechanical properties of aromatic polyesters. 

Adipic acid aliphatic copolyesters Biodegradable polyester used in degradable plastic... 

Blends of poly(3-hydroxyalkanoic acid)s (PHAs) with various natural and synthetic polymers have been reported as reviewed in Refs. [21,22]. By blending with synthetic polymers it is expected to control the biodegradability, to improve several properties, and to reduce the production cost of bacterially synthesized PHAs. The polymers investigated as the blending partners of PHAs include poly(ethylene oxide) [92, 93], poly(vinyl acetate) [94], poly(vinylidene fluoride) [95], ethylene propylene rubber [94, 96], po-ly(epichlorohydrin) [97, 98], poly(e-caprolactone) [99], aliphatic copolyesters of adipic acid/ethylene glycole/lactic acid [100] and of e-caprolactone/lactide... 

A large number of biodegradable polyesters are based on petroleum resources, obtained chemically from synthetic monomers [Okada, 2002 Albertsson and Varma, 2002 Vert et al., 1995 Sinclair, 1996 Lunt, 1998 Steinbuchel, 2003 Bigg, 1996]. According to the chemical structures, we can distinguish polycaprolactone, aliphatic copolyesters, and aromatic copolyesters. All these polyesters are soft at room temperature [Averous and Pollet, 2012]. 

A large number of aliphatic copolyesters based on petroleum resources are biodegradable copolymers. They are obtained by the combination of diols such as 1,2-ethanediol, 1,3-propanediol, and 1,4-butadenediol and of dicarboxylic acids such as adipic, sebacic, and succinic acid. 

PBS is one of the members of the family of biodegradable aliphatic polyesters. A number of copolymerization attanpts have been made to improve its properties (Darwin et al. 2003 Jin et al. 2000b, c, d, 2001). For example, Jin et al. (2000b, c) introduced phenyl units into the side chain of PBS, leading to better biodegradability of the copolyesters. Jung et al. (1999) successfully synthesized new PBS copolyesters containing alicyclic 1,4-cyclohexanedimethanol. 

With the twin driving forces of usefulness and eventual biodegradation, many studies have been made on the biodegradation of copolyesters containing aromatic and aliphatic segments to develop greener materials [58-79]. 

C. Bastioli, T. Milizia, G. Eloridi, A.S. Lallaro, G. Celia, and M. Tosin, Biodegradable aliphatic-aromatic copolyester, US Patent 8193300, assigned to Novamont S.p.A. (Novara, IT), June 5, 2012. 

Compositions have been developed that include a biodegradable aliphatic-aromatic copolyester, i.e., poly(tetramethylene adi-pate-co-terephthalate) and a plasticizer. The composition exhibits a moisture vapor transmission rate of at least 400 (1). 

Compared to totally aliphatic copolyesters, aromatic copolyesters are often based on terephthalic acid. Figure 17.2 and Table 17.2 show, the chemical structure and the properties of such products, respectively, (e.g., Eastar Bio from Eastman). Besides, BASF and DuPont commercialize aromatic copolyesters under Ecoflex (Steinbuchel and Doi 2002) and Biomax trademarks, respectively. Biomax shows a high terephthalic acid content that modifies some properties such as the melting temperature (200°C). But, according to Muller et al. (1998), an increase of terephthalic acid content tends to decrease the degradation rate. Ecoflex biodegradation has been analyzed by Witt et al. (2001). They concluded that there is no... 

Poly(butylene succinate-co-adipate)/PLA Blends Poly(butylene succinate adipate), poly(butylene succinate-co-adipate), or poly(butylene succinate-co-butyl-ene adipate) (PBSA) is a random aliphatic copolyester comprised of 1,4-butanediol, succinic acid, and adipic acid [157]. PBSA has lower thermal properties (Tg of —45°C, Tc of 50-53°C, I m of 93-95°C, crystallinity of 20-35%, and HDT at 0.45 MPa of 69°C), more flexibility (tensile strength of 34 7 MPa, tensile elongation of 400-900%, and flexural modulus of 323-340 MPa), and a faster biodegradation rate than PBS [142, 157]. PBSA/PLA blends are immiscible, and a complicated cocontinuous phase (domains of the other polymers dispersed in each continuous phase) was observed... 

The biodegradation behaviour and mechanism of aliphatic copolyester poly(butylene succinate-co-butylene achpate) (PBSA) by Aspergillus versicolor isolated from compost was... 

Biodegradation of natural and synthetic copofyesters in two different natural environments, i.e. in compost with activated sludge at a sewage farm and in the Baltic Sea, was studied by Rutkowska et al. [142]. The results revealed that the natural aliphatic copolyester 3-hydroxybutyrate-co-3-lydroxyvalerate (PHBV) and its blends with the synthetic aliphatic-aromatic copolyester of 1,4-butanediol with adipic and terephthalic acids degraded faster in compost than in seawater. In both natural environments, blends degraded faster than aliphatic-aromatic copolyester, but at a slower rate than natural component PHBV... 

Zhang E, Huang E, Wang B. Characterization of biodegradable aliphatic/aromatic copolyesters and their starch blends, Polym.-Plast Technol Eng. 41 (2002) 273. 

The majority of petroleum-based compostable plastics belong to the polyester family, including Ecoflex , polycaprolactone (PCL), Ecovio , poly-butyrate adipate terephthalate (PBAT), and aliphatic copolyesters (The Impacts of Degradable Plastic Bags in Australia 2003). Table 4.14 lists several commercially available biodegradable or compostable plastic products. 

Ecoflex is an aromatic-aliphatic copolyester that is produced from petroleum-based products, for example, terephthalic acid, adipic acid, and 1,4-butanediol. The compostable plastic is an excellent biodegradable material for blown film and sheet products, for example, grocery bags, lawn and leaf bags, agricultural mulch films. 

Novamont patented a series of biodegradable aliphatic/aromatic copolyesters which are prepared by the copolymerisation of diol components with aromatic diacids and long chain aliphatic diacids of natural origin, such as azelaic, sebacic and brassylic acids [64-67]. 

Table 10.2 History of the development of biodegradable aliphatic-aromatic copolyesters ...

In 2011, Samsung Fine Chemicals acquired the technology and patents of IRE Chemicals for the production of EnPol, a biodegradable polyester resin. The IRE original resin EnPol G8000 series was based on a group of aliphatic copolyesters composed of adipic acid, succinic acid, 1,2-ethanediol and/or 1,4-butanediol [72], The producer stated that EnPol polymers met the specifications of the FDA for food contact and the United States Pharmacopeia specifications for medical device applications. 

The main characteristics of biodegradable aliphatic-aromatic copolyesters are detailed in Section 10.3.1 and Table 10.3. Data has been taken from the technical bulletins available from the producers. 

The appropriate combination of aromatic and aliphatic components allows the manufacture of statistical copolyesters that are simultaneously biodegradable (aliphatic contents) and exhibit good mechanical resistance (aromatic contents) utilizing conventional polycondensation technology. Figure 5.382 [986]. In particular... 

Ki, H.C., Park, 0.0. Synthesis, characterization and biodegradabUity of the biodegradable aliphatic-aromatic random copolyesters. Polymer, 42 (2001), p. 1849 1861... 

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 . 

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