Poly blends with thermoplastic starch

Ren, J., Fu, H., Ren, T., and Yuan, W. (2009]. Preparation, characterization and properties of binary and ternary blends with thermoplastic starch, poly(lactic acid] and poly(butylene adipate-co-terephthalate]. Carboh dnPoI m., 77, 576-582. 

In the context of this chapter, the use of thermoplastic starch in blends with thermoplastic resins is of the main interest. As shown in Table 16.11, several blends have been developed, e.g., with vinyl alcohol copolymers (EVAl), polyolefins, aliphatic polyesters such as poly-e-caprolactone (PCL) and its copolymers, or polymers of glycols (e.g., 1,4-butanediol) with succinic, sebacic, adipic, azelaic, decanoic or brassihc acids, PCL + PVC. Compatibilization is possible by amylose/EVAl V-type complexes, starch grafted polyesters, chain extenders like diisocyanates, epoxies, etc. [Bastioli et al., 1992, 1993]. 

George, E. R., Sullivan, T. M., Park, E. H. (1994). Thermoplastic starch blends with a poly(ethylene-co-vinyl alcohol) Processability and physical properties. Polymer Engineering and Science, 34, 17-23. 

Other effective plasticizers for starch for imparting melt processibility include a variety of low molecular weight compounds, such as glycerol and diethylene glycol, and also polymers such as poly(ethylene-co-vinyl alcohol) [55]. Furthermore, starch plasticized in that manner can be melt blended with minor amounts of hydrophobic thermoplastics, such as polyethylene and poly( methyl methacrylate), to obtain biodisintegratable molded articles with good mechanical properties. 

Poly-8-caprolactone (PLC) is a synthetic, biodegradable (both linear and cross-finked) polyester with MW > 20 kg/mol. It may be processed as a thermoplastic. Owing to miscibility with PVC it is used as plasticizer and frequently blended with starch to use for films, sheets and injection molded parts, viz. Mater-Bi (see Part 16.8.1). PCL is manufacmred by Union Carbide, Daicel and Interox. Its mechanical properties are similar to these of PE [Bastioli, 1997]. 

George, E., and Park, E. H., Thermoplastic Starch Blends with Poly(vinyl alcohol . Symposium on Engineered Polymer Blends IV Theory and Practice, Poytech. Univ., Jan 22, 1993. 

In practice, the techniques of blending, compositing and nano-reinforcement are often used together. Thermoplastic starch/poly(vinyl alcohol) (PVOH)/clay nanocomposites exhibited the intercalated and exfoliated structures [260]. Mont-morillonite (MMT) with three types of cation or modifier (Na", alkyl ammonium ion, and citric acid) was examined. The prepared nanocomposites with modified montmorillonite indicated a mechanical improvement in the properties, in comparison with pristine MMT. 

Liao et al. [261] reported biodegradable nanocomposites prepared from poly(lactic acid) (PLA) or acrylic acid grafted poly(lactic acid) (PLA-g-AA), titanium tetraisopropylate, and starch. Arroyo et al. [262] reported that thermoplastic starch (TPS) and polylactic acid (PLA) were compounded with natural montmorillonite (MMT). The TPS can intercalate the clay structure and that the clay was preferentially located in the TPS phase or at the blend interface. This led to an improvement in tensile modulus and strength, but a reduction in fracture toughness. 

G. li, P. Sarazin, W.J. Orts, S.H. Imam, B.D. Favis, Biodegradation of thermoplastic starch and its blends with poly(lactic acid) and polyethylene Influence of morphology. Macromol. Chem. Phys. 212, 1147-1154 (2011)... 

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) combines the thermo-mechanical properties of PE (strength, flexibility, ductility, toughness, elasticity) with the physical-chemical properties (compatibility) of polyesters (printability, dyeability, barrier performance). It forms blends with PLA and thermoplastic starch. 

Teixeira, E., Curvelo, A., Correa, A., Marconcini, J., Glenn, G., and Mattoso, L. (2012) Properties of thermoplastic starch from cassava bagasse and cassava starch and their blends with poly (lactic acid). Industrial Crops and Products, 37(l) 61-68. 

The properties of PLA can be modified by polymer blending techniques. PLA has been blended with several synthetic and biopolymers in order to enhance its properties and to obtain novel materials. PLA has been blended with rubbers, thermoplastic starch (TPS), poly(butylene succinate) (PBS), poly(butylenes succinate adipate) (PBSA), poly(butylene... 

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