Syntheses and properties of PI/clay hybrids

Abstract

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