Rheology and structuring in organo-ceramic composites

Abstract

Abstract The processing–structure–property relationships for calcium aluminate based organo-ceramic composites are reviewed. Processing behavior was measured with a torque-outfitted Banbury mixer, structuring behavior was analyzed with electron microscopy, and mechanical properties were determined using flexural strength measurements. These results are discussed for composites composed of either a polyvinyl alcohol or phenol formaldehyde resin organic phase. The two materials have different processing behaviors, driven by different paste formation mechanisms, but are observed to have similar microstructure and mechanical properties. The rheology of model, non-calcium aluminate based composites was studied using a lubricated squeezing flow rheometer. The relaxation modulus following a step strain was measured for reactive systems that stiffened due to a crosslinking polymer phase or a polymerizing polymer phase and compared to that measured for non-reactive polydimethyl siloxane (PDMS) systems with filler fractions from 0 to 65% by volume and 65% filled PDMS of differing molecular weights. Comparison of the normalized relaxation moduli of the model reactive and non-reactive materials suggests similarities between the effect of filler amount and crosslinking amount and between the combined effects of molecular weight and filler amount and the degree of polymerization.