Nanocomposite biodegradability

Ray, S.S. and Bousmina, M. 2005. Biodegradable polymers and their layered silicate nanocomposites In greening the 21 century materials world. Progress in Materials Science 50 962-1079. 

Sinha, R.S., Yamada, K., Okamoto, M. and Ueda, K. 2002. New polylactide/layered silicate nanocomposite A novel biodegradable material. Nano Betters 2 1093-1096. 

Zhenyang, Y., Jingbo, Y., Shifeng, Y., Yongtao, X., Jia, M. and Xuesi, G. 2007. Biodegradable poly(L-lactide)/poly(3-caprolactone)-modified montmorillonite nanocomposites Preparation and characterization. Polymer 48 6439-6447. 

Biodegradable Polymer-based Nanocomposites Nanostructure Control and Nanocomposite Foaming with the Aim of Producing Nano-cellular Plastics... 

In 2002, Lee et al. [51] reported the biodegradation of aliphatic polyester-based nanocomposites under compost. Figure 9.13(A, B) represent the clay content dependence of biodegradation of APES-based nanocomposites prepared with two different types of MMT clays. They assumed that the retardation of biodegradation was due to the improvement of the barrier properties of the aliphatic APSE after nanocomposite preparation with clay. However, there are no data about permeability. 

Recently, Yamada and Okamoto et al. [52-54] first reported the biodegradability of neat PLA and PLA-based nanocomposites prepared with trimethyl octadecylammo-nium-modified MMT (MMT-Ci8(CH3)3N+) with a detailed mechanism. The compost... 

Fig. 9.14 (A) Photographs of biodegradability of neat PLA and PLA-based nanocomposite recovered from compost with time. Initial size of the crystallized samples was 3 x 10 x 0.1 cm3.

K. Okamoto and M. Okamoto also investigated the biodegradability of neat PBS before and after nanocomposite preparation with three different types of OMLF. They used alkylammonium or alkylphosphonium salts for the modification of pristine layered silicates, and these surfactants are toxic for microorganisms [56]. 

Fig. 9.15 (A) Degree of biodegradation (i.e., C02 evolution), and (B) time-dependent change of matrix Mw of neat PLA and PLA-based nanocomposite (syn-FH = 4 wt%) under compost at 58 + 2°C. Reprinted from [53], 2004 WILEY-VCH.

Fig. 9.16 Biodegradability of neat PBS and various nanocomposite sheets (A) under compost, and (B) under soil field. Reprinted from [56], 2003 John Wiley Sons, Inc.

Except for the PBS/SAP-qC16 (n-hexadecyl tri-n-butyl phosphonium cation modified saponite) system, the degree of degradation is the same for other samples. This indicates that MMT or alkylammonium cations, and at the same time other properties, have no effect on the biodegradability of PBS. The accelerated degradation of PBS matrix in the presence of SAP-qC16 may be due to the presence of alkylpho-sphonium surfactant. This kind of behavior is also observed in the case of PLA/MMT-based nanocomposite systems. 

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