Syntheses and properties of PI/clay hybrids

A new organomontmorillonite (CM) for PI hybrids has been developed by ion-e xchange reaction of cetyl pyridum chloride with Na+ montmorillonite (MMT). Polyimide/clay hybrids have been synthesized by employing two methods. Meth od I is by first blending a dimethylacetamide (DMAC) solution of 4,4'-oxydi aniline diamine (ODA) with a DMAC dispersion of CM before adding pyromellit ic dianhydride (PMDA). Method II is by blending a DMAC solution of poly(ami c acid) with a DMAC dispersion of CM. Tensile, thermal, dielectric, and wat er-absorption properties of hybrids prepared by these two methods have been studied in detail. Results show that these properties depend on the clay t ype (organophilic or not), clay concentration, and the method to synthesis hybrids. The CM concentration of 3 wt% in the hybrid by Method II results i n optimum properties in tensile strength, modulus, elongation, coefficient of thermal expansion (CTE), and water absorption. (C) 2001 John Wiley & Son s, Inc.