Filling of Epoxy Polymers with Chemically Precipitated Chalk from Chemical Water Treatment Sludge

The results of the use of chemically precipitated chalk as an active highly dispersed filler in compositions based on epoxy oligomers are presented. Used chemically precipitated chalk (original and hydrophobized), obtained by precipitation, dehydration, drying and classification of sludge from the chemical water treatment plant. To achieve the homogeneity of composites, two methods of preparing the reaction mixture for curing are considered: the introduction of the filler initially into the epoxy oligomer and the introduction of the filler into the amine hardener. Depending on the method of filler introduction and its concentration in the binder (0.5–5.0% of the mass of the epoxy oligomer), the developed formulations can be recommended for obtaining adhesives and coatings, as well as as structural composites. To study the mechanical properties, the method of determining the microhardness was used, which made it possible to evaluate the effect of the size of the filler particles and to carry out a comparative assessment of their effectiveness with small amounts of carbon-containing nanofillers (0.005–0.5%).