The main problem, solved in this thesis is the assessment of the possibility of
use domestic calcite materials in protective and decorative thin-layer coatings. It is
solved by the materials selection, mechano-chemical modification and surface
treatment, which helps to optimize an interaction of the mineral filler surface and the
polymer matrix of composite coating.
Stages of the problem solution correspond to a sections of the thesis. The proper
literature analysis and subsequent materials selection establishes the base for the
required raw materials properties change. The broad study of material’s surface
chemistry and physical chemistry properties, chemical, mineralogical composition and
particle parameters provides the selection of optimal materials. The selection was based
on the theoretical concept of ideal inactive filler for thin layer compounds. On the next
stage were studied the features of material surface treatment, mainly with siloxane
agents and, further, the interaction of the treated surface with the polymer. At the last
stage the connection between the composite structure and components ratio and the
technical properties of coatings (including corrosion resistance, durability, mechanical
resistance etc.) was established.
The level of physicochemical properties of domestic sedimentary chalk was
compared to Turkish calcite based on ground marble. Approaches on the regulated
modification of fillers surface chemistry are tested and optimized.
During a work on the thesis the modern instrumental methods of chemical
analysis, such as differential thermogravimetry, infrared spectroscopy, x-ray
diffraction analysis, sorption measurement techniques were used to characterize
materials properties.
It was shown, that different grades of the chalk from Ukrainian deposits have the
significant property divergence in terms of chemical composition, mineral forms and
surface properties. It was found that the grades MTD-1 and MMS-2 from Sumy and
Novgorod Siversky deposits are much closer by their properties to the inactive
grounded marble than others.
A method for mechano-chemical modification of chalk in the presence of
functional siloxanes is considered, the optimal process parameters are determined. The
method used included the combined grinding of the raw material with ball mill in the
presence of siloxane chemistry modificators. The effect of the surface treatment was
estimated by the measurement of it’s sorption values, wicking kinetics and the rheology
of suspensions of modified chalks. It was shown that the better degree of the polarity
decrease for the carbonaceous surface is obtained by the use of hydrid-siloxane liquid,
while salts – sodium and potassium siliconates – are less effective.
It was shown, that the modification of siloxane surface leads to the increase of
compatibility of the filler and the polysiloxane matrix polymer, especially in the case
of hydrid-silane treatment.
This leads to the significant improvement of technological properties and the
protective ability of coatings. For instance, the use of treated chalk increased the
atmospheric deterioration time almost 2,5 times, corrosion resistance – more than
twice. Such parameters as coatings vibrational, radiation and bio-resistance were also
increased.
Obtained formulations of coating on a base of sedimentary chalks were
optimized. The level of their operational and protective properties with respect to
substrates of various chemical nature under the action of destructive environmental
factors are estimated.
The composition developed was implemented industrially: the batch of 10 tons
was produced and successfully tested using respective performance testing methods.
Key words: polymethylphenylsiloxane, protective coatings, chalk, calcium
carbonate, silicone, hydroxosilane, rheology, wetting, wetting angle, adsorption,
weather resistance, corrosion resistance
