Silica-filled composite materials

The properties of silica-filled rubber and composites depends primarily on the association of individual primary silica particles in the final material. The association of primary particles is believed to be a reversible process responsible for the physical properties of the filled material at low strain levels. This process is furthermore believed to an essential mechanism explaining the improvement of dynamic properties of filled rubber, as opposed to carbon black, silica particles are characterized by a strongly polar surface able to generate a strong interaction. The interaction is reversible and leads to reduced hysteresis. 

Zhou, H. J., Rong, M. Z., and Friedrich, K. 2006. Effects of reactive compatibilization on the performance of nano-silica filled polypropylene composites. Journal of Materials Science Letters 41 5767-5770. 

Gel-filled mineral porous material Silica filled with dextran gels. Composite porous particles filled with viscoelastic synthetic gels High sorption capacity at high flow rates, high resolution, noncompressibility HyperD, BioSepra... 

It is worth pointing ont here that the manifestations of internal stresses in single-phase crystalline materials (such as MgO, CaO, and gypsum) do not in any way limit their variety in more complex structures, for example, in snch two-phase materials as amorphous silica or aluminum-modified silica filled with various crystals, or in even more complex materials, such as cement compositions. 

As can be seen, the model fits reasonably well the experimental G data but cannot meet the asymmetric shape of G" vs. strain data. The exponent m is depending on the reinforcing character of the filler, as well as the critical strain y. A similar assessment of the Kraus equations with a silica (40 phr) filled polydimethylsiloxane composite yielded the same conclusions regarding the low strain deficiencies of Equation 5.39. For such a silica filled material, fit parameter values were as expected different, i.e., 0.02 and m 0.45 for G (Yo) Yc 0.01 and m 0.35 for G"(Yo)-... 

Shang, W., Williams, J., Soderiiolm, K. How the work of adhesion affects the mechanical properties of silica-filled polymer composites s. Journal of Materials Science 29 2406-2416(1994)... 

Industrial grade materials employ fillers such as asbestos, silica and glass fibre. These are incorporated by dry-blending methods similar to those used with woodflour-filled phenolic compositions. 

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