A FUNDAMENTAL MODEL FOR PREDICTION OF OPTIMAL PARTICULATE COMPOSITE PROPERTIES

Particulate composite systems comprising a high content of granular fi ller (over 60% by weight) in a polymer matrix are greatly influenced b y the filler-to-binder ratio, the size distribution of the filler part icles and the amount of wetting and adhesion between the filler and th e matrix. Relative density and mechanical compressive properties prese nt sensitive variables for studying these effects. Two principal model s are presented, one for evaluating the optimal filler size distributi on (gradation) and the other to determine the optimal matrix content f or this evaluated gradation. Adopting both models provides a predictio n of a composite system with enhanced mechanical properties and optima l compaction. The constants of both models are derived experimentally using an epoxy/SiC mixture. The optimal distribution of the matrix bet ween the various filler components and the optimal filler gradation of the composite system are thus obtained. Results show that, despite it s low content, the fine filler plays a major role in determining the t otal optimal composite mixture. Slightly different constants are deter mined for the various properties tested. Optimal formulation can thus be specified for either a critical property desired or a mean optimum for all relevant properties. Experimental verification of both models proves their efficiency in predicting optimal mixture parameters in or der to achieve the best performance of the polymerized composite syste m.