Biodegradable nanocomposites

The state-of-the-art in the field of biodegradable nanocomposites has been reviewed (40,41). Biodegradable biobased nanocomposites can be made from ceUulosic materials, corn-derived plastics, and poly(hydroxyalkanoate)s. The latter materials are fabricated from bacterial resources. 

In combination with nanoclays, nanocomposites can be produced for a wide field of applications. Even low loadings of nanoclays with high aspect ratios to biopol5miers can have a profoimd enhancing effect over the material properties (42). Such nanocomposites have an improved strength and stiffness, a low gas vapor permeability, a low coefficient of thermal expansion, and an increased heat deflection temperature. However, in this field also some technical difficulties emerge, but these can be circumvented (40). 

The preparative techniques for the production of bio nanocomposites are based largely on existing techniques for the processing of ordinary plastics. The processes can be classified into three main categories (41)  

---

Mangiacapra, R, Gorrasi, G., Sorrentino, A., Vittoria, V (2005). Biodegradable nanocomposites obtained by ball milling of peetin and montmorillonites. Carbohydrate Polymers, 64, 516-523. 

HUA 06] Huang M.F., Yu J.G., Ma X.F., High mechanical performance MMT-uiea and formamide-plasticized thermoplastic cornstarch biodegradable nanocomposites , Carbohydrate Polymers, vol. 63, no. 3, pp. 393-399,2006. 

Cadebo, L., Feijoo, J. L., Villanueva, M. R, Lagaron, J. M., Gimenez, E. Optimization of biodegradable nanocomposites based on aRLA/PCL blends for food packaging applications. Macromol. Symp., 2006, 233, 191-197. 

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. 

It is important when creating biodegradable nanocomposites that high demands are placed on the environmental impact of the surfactant. The DMA performed to investigate the thermal properties of the produced materials showed that the introduction of CNW were able to improve the storage modulus of PLA in the plastic zone. The researchers stated that the well dispersed CNW have a large potential in improving the mechanical properties of biopolymers such as PLA. 

Cheng, Q. Wang, S. Zhou, D. Zhang, Y. Rials, T. (2007b). Lyocell-derived cellulose fibril and its biodegradable nanocomposite. Journal of Nanjing Forestry University, Vol. 31, No. 4, pp. 21-26, ISSN 1000-2006... 

Wibowo, A.C., Misra, M., Park, H.-M. etal. (2006) Biodegradable nanocomposites from ceUulose acetate mechanical, morphological, and thermal properties. Composites A, 37,1428-1433. 

An epoxidized triglyceride oil was subjected to intercalation into an organically-modified clay, followed by acid-catalyzed curing of the epoxy-containing triglyceride, leading to the production of a new class of biodegradable-nanocomposites from inexpensive renewable resources. 

A. Alemdar, M. Sain, Biodegradable nanocomposites from wheat straw, in Proceedings of the AlChE 2006 Annual Meeting, San Francisco, CA, Nov. 12-17, 2006. 

Keywords Biodegradable nanocomposites, layered silicates, renewable resources, blends... 

There have been a number of studies dedicated to organically modified layered silicate reinforced completely biodegradable nanocomposites to target highly exfoliated structures. Renewable resources-based biodegradable polymers utilized so far for the preparation of nanocomposites are poly(lactic acid) (PLA) [40-68,11-15], poly(3-hydroxy butyrate) (PHB) [69,16-20] thermoplastic starch [71-77,21-25], plant oils [78-81,26-30], cellulose [82,83,30,31], etc. The following section deals with the transformation of the properties of renewable sources-based biodegradable polymers as their layered silicate nanocomposites. 

Fujimoto Y, Sinha Ray S., Okamoto M., Ogami A., Yamada K., Ueda K., Well-controlled biodegradable nanocomposite foams From microcellular to nanoceUular, Macromol. Rapid. Commun., 24, 2003, 457 61. 

Y. Fujimoto, et al, Well-controlled biodegradable nanocomposite foams from microcel-lular to nanocellular, Macromolecular Rapid Communications 24 (7) (2003) 457-461. 

A non-biodegradable nanocomposite based on polyhedral oligomeric silsesquioxane nanocages with poly(carbonate urethane) has been developed (33). A good ceU-compatibility and antithrombo-genic properties have been noticed. 

Yu X et al (2009) Influence of in vitro degradation of a biodegradable nanocomposite on its shape memory effect. J Phys Chem C 113(41) 17630-17635... 

Sharih, S., et al. 2012. Biodegradable nanocomposite hydrogel struemres with enhanced mechanical properties prepared by photo-crosslinking solutions of poly (trimethylene carbonate)-poly (ethylene glycol)-poly (trimethylene carbonate) macromonomers and nanoclay particles. Acta Biomaterialia 8(12) 4233-4243. 

Raghunath J, Geoigiou G, Armitage D, Nazhat SN, Sales KM, Butler PE, et al. Degradation studies on biodegradable nanocomposite based on polycaprolactone/polycarbonate (80 20%) polyhedral oligomeric silsesquioxane. J Biomed Mater Res Part A December 1, 2009 91A(3) 834-44. 

Nanocomposites are usually defined as a combination of two or more components or phases in which the reinforcement material has one dimension in the nanometer range (1-100 nm) [22,80,81]. The terminology usually refers to a polymer (thermoplastic or thermosetting) matrix that represents the continuum phase, while reinforcements are able to induce enhanced performances (e.g., mechanical, thermal, etc.) from the composite. In biodegradable nanocomposites, also called bionanocomposites, matrices may... 

In this chapter a review of the most important and recent researches on development and characterization of biodegradable nanocomposites based on starch reinforced by different types of nanofillers were exposed. Particularly, the investigation was... 

From the results reported in the different works cited in this chapter, it can be concluded that in order to improve the barrier, mechanical and thermic properties of a starch matrix, the next considerations need to be taken into account (a) morphological and chemical characteristics of the employed nanofillers (b) the reactive groups in their surface, as well as their crystalline fraction (this depends on the methodology employed for their obtaining) (c) the variables involved in the biodegradable nanocomposites manufacture. 

Shih YF, Wang TY, Jeng RJ, Wu JY, Teng CC (2007) Biodegradable nanocomposites based on poly(butylene succinate)/organoclay. J Polym Environ 15(2) 151-158... 

---