Polymer-layered crystal nanocomposites

Based on their dimensions, which are in the nanometre range, three types of fillers can be distinguished. Isodimensional nanoparticles (NP), such as spherical silica NP have three nanometric dimensions. Nanotubes or whiskers are stretched constructions in which two dimensions are in the nanometre range and the other dimension is larger. When only one dimension is in the nanometre range, the composites are termed polymer-layered crystal nanocomposites, and are obtained by the complete intercalation of the polymer inside the galleries of layered host crystals [2]. 

Alexandre M, Dubois P (2000) Polymer-layered silicate nanocomposites preparation, properties and uses of a new class of materials. Mater Sci Eng Rep 28 1-63 Araki J, Kuga S (2001) Effect of trace electrolyte on liquid crystal t)q)e of cellulose microcrystals. Langmuir 17 4493 1496... 

Xie, Y., Yu, D., Kong, J., Fan, X., and Qiao, W. 2006. Study on morphology, crystallization behaviors of highly filled maleated polyethylene-layered silicate nanocomposites. Journal of Applied Polymer Science 100 4004-4011. 

The combustion of the LDH nanocomposites leads to the formation of an intercalated nanostructure of mixed metal oxides (produced by thermal degradation of LDH) and char. This hypothesis is supported by XRD, due to the presence of a peak at 1.28 nm in the epoxy-LDHl and epoxy-LDH2 after the UL-94 test. It is interesting to note that Gilman et al. reported an intercalated structure of char from montmorillonite nanocomposites, with the same interlayer spacing of the chars, 1.3 nm, independent of the chemical structure of the polymer (thermoplastic or thermosetting) or nanostructure (delaminated or intercalated). The same value observed in an LDH-based nanocomposite (1.28 nm) shows that the interlayer spacing in the char may be independent of the nature of the layered crystal. 

The structure, the thermal properties and the kinetics of crystallization in high polymer content poly(ethylene oxide)/ layered silicate nanocomposites were investigated utilizing XRD, DSC and POM in order to understand the effect of the presence of the inorganic surfaces on the crystallization mechanism. In all cases, intercalated structures with bilayers of polymers chains inside the galleries were obtained. The crystallinity was found to be relatively constant, whereas the... 

Among all nanoparticles, nanoclays and POSS are the most extensively researched group of nanoparticles. Nanoclays (layered silicates) belong to the layered silicate family. Nanoclays or layered silicates (LS) have been more widely investigated in the literature as it is easy to access. Layered silicate nanocomposites exhibit markedly improved barrier, mechanical, thermal properties with respect to the pure polymer or conventional composites [14,15]. Layered silicates are briefly classified according to the types and the relative content of the unit crystal lamellae [16] the layered silicates are divided into three types ... 

Costa, F. R., Saphiannikova, M., Wagenknecht, U., and Heinrich, G., Layered double hydroxide based polymer nanocomposites, Adv. Polym. Sci. (2008), 210(Wax Crystal Control Nanocomposites Stimuli-Responsive Polymers), 101-168. 

In the isothermal crystallization of polypropylene montmorillonite (PP-MMT) nanocomposites, it was found that the crystallinity of the composites decreased with increasing montmorillonite content, indicating the dispersion of MMT layers in the polypropylene matrices. The nanoparticles confined the polypropylene chains and hindered the polymer crystallization. The spherulites of the PP-MMT nanocomposites were greatly decreased in size as MMT was introduced. On the other hand, the crystallization rate increased dramatically with the increasing of MMT content. The interfacial free-energy per unit area perpendicular... 

Pan, R, Zhu, B., Dong, T. and Inoue, Y. (2008) Poly(L-lactide)/layered double hydroxides nanocomposites Preparation and crystallization behavior. Journal of Polymer Science Part B Polymer Physics, 46, 2222-2233. 

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