BICONTINUOUS NETWORKS MADE OF POLYPHOSPHATES AND OF THERMOPLASTIC POLYMERS

Composite films are obtained by casting aqueous dispersions obtained b y admixture of PVAc or styrene-acrylic latexes with aluminium or iron polyphosphate powders. Film extraction with solution of aqueous EDTA ( a solvent for polyphosphate) yields a dense polymer film, but using a polymer solvent (chloroform) a porous monolithic solid is obtained. Co mposite and solvent-extracted films were characterized by SEM coupled to energy dispersive X-ray analysis, and by Raman microspectrophotomet ry. The results from morphological, spectral and gravimetric experimen ts show that the cast films are bicontinuous, indicating a strong comp atibility of the organic and inorganic phases. This is assigned to ion ic bonds at the interfaces, in which aluminium ions act as bridging gr oups. (C) 1997 Elsevier Science Ltd.