Analytical Techniques for Characterising Filler Surfaces

David P. Ashton, David Briggs and Christopher M. Liauw 

This is solvatable by the molten polypropylene and hence is fully wetted, leading to low melt viscosities, low mould filling pressures and maximum filler loadings. In the 

The two examples described previously illustrate the importance of a number of factors concerning the surface of the filler and the interface between the filler particles and the matrix. These are summarised next  

The surface of the filler must be compatible with the molten polymer or, if a thermoset system, with the uncured system, (i.e., the resin or elastomer), to achieve the optimum rheology and filler dispersion. 

An extremely important factor not implicitly obvious in the two examples described previously is the specificity of the surface chemistry to each composite system. Of course many surface reactive agents can be used in more than one system, and MPS and stearic acid fall into this category. However, the MPS and stearic acid could not be interchanged between the two examples, not only due to the mono functionality of the stearic acid, but due to the relative lack of reactivity between silanes and calcium carbonate, and stearic acid and silica. In the latter case, the hydroxyl groups, which are formed at the silica crystal surfaces to satisfy valency demands, are acidic in nature and hence do not form strong bonds with the carboxylic acid group. If the silica was substituted, for example, with alumina then the stearic acid would interact with the surface of the filler, as the hydroxyls formed at crystal discontinuities in alumina are basic in character. 

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Analytical Techniques for Characterising Filler Surfaces Specular... 

Ashton DP, Briggs D, Liauw CM (2003) Analytical techniques for characterising filler surface. In Rothon RN (ed) Particulate-filled polymer composites. Rapra Technology Limited, Shawbury... 

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