Fractal Structure of Silica Aggregates and Branched Epoxy Polymers

Benjamin Chu

Chemistry Department, State University of New York, Stony Brook, New York 11794-3400, U.S.A.

Keywords: Branched Epoxy Polymers, Silica Aggregates, Fractal Structure

Abstract. Structures of silica aggregates and of branched epoxy polymers have been investigated by means of laser light scattering (LLS), electron microscopy (EM) and small angle X-ray scattering (SAXS). For silica particles, the fractal dimension (d_f) of the large size aggregates can be determined by either LLS or EM while for epoxy branched polymers, SAXS in combination with LLS becomes the preferred technique. With M~r^d_f (M and r being the mass and radius of the particle, respectively), d_f~1.79-1.85 were determined for silica aggregates at high temperatures (50° and 80°C), in contrast to d_f~2 for silica clusters formed at room temperatures. For branched epoxy polymers formed by curing of 1,4-butanediol diglycidyl ether with cis-1,2-cyclohexanedicarboxylic anhydride, d_f~2.1.