Biodegradable polymers polyesteramides

Polyamides and polyesteramides are more recent arrivals to the commercial biodegradable polymer field. Copolymers of either glycine or serine with e-aminocaproic acid are biodegradable. For example, biodegradable polyaspartic acid was synthesized (95% yield) at low cost [Koskan, 1992]. A copolymer of butylene-adipate and e-caprolactam was recently introduced by Bayer as BAK 1095. The material has T = 125°C, density of 1070 kg/m, tensile modulus of 180 MPa, maximum strain at break of 400%, tensile stress at break of 25 MPa, and it fully degrades in 300 days under the ASTM standard conditions. 

Multilayer co-extrusion is another technique used in the preparation of starch/ synthetic sheets or films [164, 263-266], in which TPS is laminated with appropriate biodegradable polymers to improve the mechanical, water-resistance and gas-barrier properties of final products. These products have shown potential for applications such as food packaging and disposable product manufacture. Three-layer co-extrusion is most often practiced, in which a co-extrusion line consists of two single-screw extruders (one for the inner starch layer and the other for the outer polymer layers) a feedblock a coat-hanger-type sheet die and a three-roll calendering system [164]. Biodegradable polyesters such as PCL [164, 264], PLA [164, 263], and polyesteramide, PBSA and poly(hydroxybutyrate-co-valerate) [164] are often used for the outer layers. These new blends and composites are extending the utilization of starch-based materials into new value-added products. 

Blends or composites materials have been produced by the processing of starch with biodegradable polymers such as poly(s-caprolactone), pofy(lactic acid), pofy(virtyl alcohol), pofy(ltydroxybutyrate-co-valerate), and polyesteramide. The most common are Mater-Bi from Novamorrt arrd Ecostar from Natiortal Starch. 

Synthetic biodegradable polymers are generally made by polycondensation methods from petroleum-based feedstocks. However, different from other petrochemical-based resins that may take centuries to degrade, these synthetic polyesters decompose rapidly into carbon dioxide, water, and humus under appropriate conditions where they are exposed to the combined attack of water and microorganisms [109, 116, 117). Petroleum-based biodegradable polymers that have been used in bionanocomposites are PCL, polyesteramides (PEAs), PBS, aliphatic polyesters (APES), and poly(vinyl alcohol) (PVA) [116]. 

Biodegradable polymers can also be produced from petroleum sources and are comprised of aliphatic polyesters and copolyesters (e.g., PBS, and poly(butylene succinate adipate)—PBSA), aromatic copolyesters (e.g., poly(butylene adipate terephthalate)—PBAT), poly(e-caprolactone) PCL, polyesteramides (PEA), and poly(vinyl alcohol) (PVA). Further details concerning the synthesis of these polymers can be found in the book by Rudnik (2008). In this section we summarize some of the key properties of these materials... 

Z. Qian, S. Li, Y. He, C. Li and X. Liu, Synthesis and thermal degradation of biodegradable polyesteramide based on e-caprolactone and 11-aminoundeca-noic acid , Polym Degrad Stabil, 2003, 81, 279-86. 

Fan, Y., M. Kobayashi, and H. Kise. 2000. Synthesis and biodegradability of new polyesteramides containing peptide linkages. Polymer Journal 32(10) 817-822. 

Fan Y, Kobayashi M, Rise H (2001), Synthesis and specific biodegradation of novel polyesteramides containing amino acid residues J. Pol. Sci. Part A - Polymer Chemistry, 39 (9), 1318-1328. 

Averous, L., Fauconnier, N., Moro, L and Fringant, C. (2000) Blends of thermoplastic starch and polyesteramide processing and properties. Journal of Applied polymer Science, 76,1117-28. Mani, R. and Bhattacharya, M. (1998) Properties of injection moulded starch/ synthetic polymer blends. Ill Effect of amylopectin to amylose ratio in starch. European Polymer Journal, 34 (10), 1467-75. Mani, R. and Bhattacharya, M. (2001) Properties of injection moulded blends of starch and modified biodegradable polyesters. European Polymer Journal, 37, 515-26. 

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