Ke. Strawhecker et E. Manias, Structure and properties of poly(vinyl alcohol)/Na+ montmorillonite nanocomposites, CHEM MATER, 12(10), 2000, pp. 2943-2949
Poly(vinyl alcohol)/sodium montmorillonite nanocomposites of various compos
itions were created by casting from a polymer/silicate water suspension. Th
e composite structure study revealed a coexistence of exfoliated and interc
alated MMT layers, especially for low and moderate silicate loadings. The i
norganic layers promote a new crystalline phase different than the one of t
he respective neat PVA, characterized by higher melting temperature and a d
ifferent crystal structure. This new crystal phase reflects on the composit
e materials properties. Namely, the hybrid polymer/silicate systems have me
chanical, thermal, and water vapor transmission properties, which are super
ior to that of the neat polymer and its conventionally filled composites. F
or example, for a 5 wt % MMT exfoliated composite, the softening temperatur
e increases by 25 degreesC and the Young's modulus triples with a decrease
of only 20% in toughness, whereas there is also a 60% reduction in the wate
r permeability. Furthermore, due to the nanoscale dispersion of filler, the
nanocomposites retain their optical clarity.