1. Field of the Invention
The present invention relates in general to a method for preparing polymer composites. More particularly, it relates to a method for preparing a nanocomposite comprising a vinyl polymer matrix having dispersed therein layered silicate particles.
2. Description of the Related Arts
Nanocomposites are a new class of materials which exhibit ultrafine phase dimensions, typically in the range 1-100 nm. Experimental work on these materials has generally shown that virtually all types and classes of nanocomposites lead to new and improved properties when compared to their micro- and macrocomposite counterparts.
A specific category of polymer nanocomposites has been described as a composite material comprising a polymer matrix containing a polyamide having uniformly dispersed therein layers of silicate. This polyamide composite was reported to exhibit enhanced stiffness, strength, and heat resistance. The improvements in properties observed with these nanocomposites are significant when compared (on an equal weight basis of particulate filler) to those conventionally prepared composites.
In J. Mater. Sci.,31(13), 3589-3596, 1996, a method is disclosed for making polystyrene nanocomposites wherein montmorillonite which has been surface modified with vinylbenzyltrimethylammonium is mixed with styrene monomer and a suitable organic solvent and then polymerization is effected in the presence of the organic solvent. The interlayer spacing of the montmorillonite contained in the resulting composite is expanded to 1.72-2.45 nm (from 0.96 nm).
Similarly, in Japanese Laid Open Patent Application No. 63-215,775, a layered clay material is surface modified by a vinyl-containing ammonium salt by an ion exchange mechanism and then mixed with an organic solvent and a vinyl monomer, followed by polymerization. As further background for the preparation of vinyl polymer nanocomposite, attention is directed to Japanese Laid Open Patent Application No. 08-151,449.