Abstract: A coated particulate filler to the surface of which there is bound an acid group-containing organic polymer which also comprises a nitrogen-containing group capable of reacting with an organic polymeric material. The acidic group may be a carboxylic acid group and the nitrogen-containing group may be an amide group or an amine group, especially a alkylamine or a polyakylamine derivative of an amine group. The organic polymeric material may contain ethylenically unsaturated groups or halogen groups, and reaction may take place during cross-linking of the organic polymeric material. Compositions comprising coated particulate filler and organic polymeric material have improved tensile modulus.

Abstract: A polymer composite is produced by polymerizing an olefine monomer in the presence of a catalyst system obtained by treating a filler material with (a) an organic magnesium compound which contains halogen or (b) an organic magnesium compound and thereafter with a halogen-containing compound; and then with a transition metal compound, which is preferably titanium tetrachloride, adding an organic metal activator compound and continuing the polymerization to obtain a composite containing desired proportions of polymer and filler. The filler may be carbon, an aluminosilicate such as mica or talc, or glass-fibre. Homogeneous composites, in respect of the distribution of filler in various size fractions, can be obtained. Composites having good flow characteristics may be obtained. The composites may be formed directly into shaped articles by suitable shaping techniques. Alternatively, the composite may be blended with a polymeric material.