Particulate acicular

Rothon RN (1994) Acicular particulate reinforcements. In Jones FR (ed) Handbook of polymer-fibre composites. Longman, Harlow, p4... 

Cohesion has often been attributed to the interlocking of fibrous or acicular particles. This could be important in the more porous parts of the material, but in the material as a whole, attractive forces between those parts of adjacent layers of C-S-H or other phases that are in contact are probably more important, both within particles and, in so far as the material is particulate, between them. The attractive forces could be direct, of the types mentioned above, or indirect, through interposed HjO molecules forming ion-dipole attractions and hydrogen bonds. Even for D-dried material, analogies with crystalline tobermorite and jennite indicate that much interlayer water is still present (Section 5.4). 

The term filler is very broad and encompasses a very wide range of materials. In this book, we arbitrarily define as fillers a variety of solid particulate materials (inorganic, organic) that may be irregular, acicular, fibrous, or plate-like in shape and that are used in reasonably large volume loadings in plastics. Pigments and elastomeric matrices are normally not included in this definition. 

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