Polymeric Coatings Composition Based on Modified Oligopiperylene Styrene Binders with Galvanic Sludge as a Filler

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Background radiation, measured with device «AQM-22» showed the absence of radioactive radiation in the product.

Research methods: the method of measuring dampening contact angle implied dripping on a base, its microphotography with further contact angle measuring with protractor, viscosity on funnel FORD №4 (ASTM D 120087), adhesion on concrete applying adhesionmeter PSO - MG4 for ASTM D 4541. Relative hardness was determined by comparing the number of oscillations of a pendulum and ball joints on glass and polymer film by pendulum ASTM D4366-95 (ISO1522:2001). Surface structure was researched with atomic-force microscopy (АFМ) at a scanning probing system Integra Aura, manufactured at NT-MDT, Zelenograd. The scanning was carried out by polysilicon sounder HA_NC applying discrete contact method. According to this method cantilever pressure on sample surface is considerably less, this allows to operate with softer and easily destructive materials like polymer films and biomaterials.

To determine integral toxicity rate of polymer paint and varnish material integral toxicity rate was apply biotest “Ecolum” at the “Biotox-10” device. Frozen-dried preparation of luminescent bacteria or enzymatic agents of bacterial luciferase.

Toxicity criterion was the determination of test-object bioluminescence intensity with the device “Biotox-10” under the impact of chemical compounds contained in the analyzed sample compared to solution free of toxic substances.

3. Experiment Results and Discussion

At the first stage of the research we have supposed that there possibly is the mechanism of interation between oligopiperylene styrene and alcoxysilane. The authors supposed that chemical bonds might be formed between these two substances due to the existence of reaction capable groups in TEOS and multiple bonds in OPPS.

The interaction product of oligopiperylene styrene and tetraethoxysilane most probably is a three-dimensional polymer, where macromolecules of OPPS are stitched by TEOS molecules. The basis of this reaction is hydrogen atoms replacement which are at allile position towards double bond of copolymer. The interaction of oligopiperylene styrene and tetraethoxysilane can proceed both from the point of view of modification by alcoxysilane polycondensation products and possible chemical interaction of these components.

The first and the second interaction variants assume the alteration of physical and physical-mechanical properties of polymer binding material.

One of the most noticeable changes during modification by alcoxysilanes is the occurrence of strong hydrophobic effect.

Figure 1. Film surface structure of oligopiperylene styrene (а) and oligopiperylene styrene, modified with ten per cent of alcoxysilane (b) at the edge of galvanic slurry particle

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The effect itself appears when alcoxysilane content in binding material is only 4%. Hydrophobic effect is usually explained by the fact that TEOS possesses functional groups of silicon atom, which promote the formation of bonds with the surface of the treated material. TEOS molecules are oriented in such a way that, for instance, a polar hydrocarbon fragments are directed towards the outer space, but polar ones – towards the treated surface. As a result the latter in protected by hydrophobic hydrocarbon groups and loses its ability to be moisteneed by water. On the treated surface the finest layer of substance is formed, but not a complete coating, due to which vapour and gas permeability preserved. This property is of great importance for numerous construction materials ^[13].

The described above experimentally tested assumptions prove the tests executed applying atomic-force microscope.

Figure 1 demonstrates 3D film surface of oligopiperylene styrene (a), modified oligopiperylene styrene with 10% of alcoxysilane (b) at the galvanic slurry particle section (extruded filling had undergone pre-lapping with the following polishing). As the research showed unmodified oligopiperylene styrene contains not numerous spheric inclusions with the diameter of 700-800 nanometers. These are probably oligopiperylene globules. Such structure is basically typical for polystyrene modified with diene oligomers. However, when introducing alcoxysilane, 3D surface image is completely changing. Almost all surface consists of comparatively shallow but numerous (100 per 1 square micrometer) formations, located athwart the coating surface. Judging by the neoformations effective diameter of 2-5 nanometer they are polarized elongated fragments of three dimension macromolecules of polymer structure, formed during the interation of TEOS and oligopiperylene styrene ^[14].

The question arises concerning the role and impact of galvanic slurry when it is introduced into the composition. As galvanic slurry consists of metals oxides and hydroxides it will undoubtedly lead to the occurrence of numerous associated hydrogen bonds between filling and binding materials. The possibility of chemical interaction of hydroxyl groups on the surface of filling and binding materials cannot be eliminated. The distribution of galvanic slurry particles in the binding material is rather homogeneous. As zinc oxide is a prevailing component so considerable spreading capacity is provided. Coloristic characteristics of calm greenish-grey color are optimal for painting most of industrial and civil buildings and structures.

During the protection coating maintenance the most important characteristic is its hardness. Relative hardness was determined applying pendular device M-3 According to the research hardness is defined by both TEOS modifier content and galvanic slurry as a filling material. Research results are presented in Figure 2.

Figure 2. Dependence surface of enamel relative hardness properties on TEOS and GS content

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OPPS-TEOS-GS composition hardness is connected with the formation of intermolecular stitches (in case of relative hardness decrease), and also with the plastification effect (in case of relative hardness decrease). The process of composition hardening has competing nature and depends on coating drying rate, on the number of the formed stitches and many other factors. Anyway great amount of alcoxysilane is unprofitable.

Nevertheless it should be noted that the highest relative hardness values are observed when galvanic slurry is added. Slurry taken from dumps contains quarts sand, which increases the hardness of the total composition.

Long-term maintenance of protective coating greatly depends on adhesion towards the coated construction material. Coating adhesion properties are determined by the complex interaction (physical, chemical, electric) of polymer functional groups and active centers of substrate material. The originated bonds impede the interaction of this material and environmental particles, i.e. corrosion process. That means, the higher is adhesion the more bonds of substrate and polymer appear, and the stronger are these bonds, the less vacant places for corrosion remain. Coating test results on the grinding concrete are presented in Figure 3.

Figure 3. Dependence surface of enamel adhesion properties on TEOS and GS content

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The research showed that solidity maximum limit for tearing off is achieved when tetraethoxysilane modifier content is 10%. Its further concentration increase considerably decreases the characteristics that might be connected to plastification effect. However galvanic slurry content does not appreciably influence hardness limit for tearing off. Thus high adhesion of film forming polymer of oligopiperylene styrene is achieved due to id modification with tetraethoxysilane. As previously described such composition macromolecules are polarized and possess a great number of chemically active functional groups, which promote the formation of oriented adsorption layer tightly binding film and substrate by tetraethoxysilane ^{[15, 16]}. Basing on the research adhesion rate in this case is determined by the force of possible physical and chemical interaction of TEOS and hydroxyl groups on the concrete substrate surface.

Figure 4. Dependence surface of toxicity index on TEOS and GS content

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Toxicity estimation of the developed paint and varnish polymer coating was executed applying the device “Biotox-10” for ecological control. The research results demonstrated (Figure 4) that the addition of 30 mass.p of GS into the formulation does not influence coating toxicity rate, which is apparently specified by a number of favorable factors: GS addition prior to composition hardening, GS homogeneous distribution along the paint and varnish film, hardening and three-dimension grid structure formation as a result of TEOS modification occurs without any hindrance from GS, and at the same time promotes safe blocking of GS, containing heavy metals ions inside three-dimension stitched structure after polymerization process and does not allow the migration from polymer film into environment. The carried analysis of developed paint and varnish water extract showed that toxicity index does not exceed 20 units, so the paint and varnish material can be referred to the materials with the admissible toxicity rate (according to MU №1.018-07) and consequently to ecologically safe materials.

Comparative characteristics of enamel KO-168 and the developed enamel containing 100 mass.p of OPPS, 30 mass.p. of GS and 10 mass.p. of TEOS with 30-35% of aliphatic solvent of total mass are given in Table 2.

Table 2. Comparative characteristics of popular enamel КО-168 and developed enamel containing 100 mass.p of OPPS 30 mass.p. of GS and 10 mass. p. TEOS with addition of aliphatic solvent 30-35% of total mass

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