Biodegradable polymers and their nanocomposites

Ogata et al. first prepared PLA/OMLS blends by dissolving the polymer in hot chloroform in the presence of dimethyl distearyl ammonium modified MMT (2C18MMT). In the case of PLA/MMT composites, XRD and SAXS results showed that the silicate layers forming the clay could not be intercalated in the 

XRD patterns and TEM observations clearly established that the silicate layers of the clay were intercalated, and randomly distributed in the PLA matrix. Incorporation of a very small amount of o-PCL as a compatibiUzer in the nanocomposites led to better parallel stacking of the silicate layers, and also to much stronger flocculation due to the hydroxylated edge-edge interaction of the silicate layers. Owing to the interaction between clay platelets and the PLA matrix in the presence of a very small amount of o-PCL, the strength of the disk-disk interaction plays an important role in determining the stability of the clay particles, and hence the enhancement of mechanical properties of such nanocomposites. 

In subsequent research, Sinha Ray et al. prepared PLACNs with organically modified synthetic fluorine mica (OMSFM). For the characterization of structure and morphology of prepared nanocomposites they first used XRD and conventional TEM (CTEM), and then CTEM and high resolution TEM (HRTEM), they examined the final structure of PLACNs. The compositions of nanocomposites of PLA with OMSFM are summarized in Table 3.1. The XRD 

Characteristic parameters Neat PLA PLACN4 PLACN7 PLACN10 

2 (a) XRD patterns of OMSFM powder and various PLACNs. The dashed line indicates the location of the silicate (001) reflection of OMSFM. The asterisks indicate the (001) peak for OMSFM dispersed in a PLA matrix. Reproduced from Sinha Ray, Yamada, Okamoto, Ogami and Ueda by permission of American Chemical Society, USA. (b) Bright field CTEM images of various crystal lized PLACNs pellets. Reproduced from Sinha Ray, Yamada, Okamoto, Ogami and Ueda by permission of American Chemical Society, USA. 

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