RubCon

Polymer concrete samples of four compositions (Table 1.2) measuring 4 x 4 x 16 cm are prepared. Control samples were placed in a desiccator containing moisture absorption silica gel composition. Other samples were in environments with various humidity. The influence of environmental humidity on the compressive strength, modulus elasticity, and moisture absorption of furfurol-acetone, epoxy, polyester, and rubber (RubCon) polymer concrete samples are shown in Tables 1.3-1.5 and Figures 1.4 and 1.5. 

Ingredients Furfurol- Acetone Epoxy Polyester Rubber (RubCon)1... 

For more detailed information about the composition and properties of RubCon, see Chapter 2. 

The samples of rubber polymer concrete (RubCon) (composition 5, Table 1.2), sized 4 x 4 x 16 cm, were tested under conditions similar to those previously described. 

The ultimate compressive strength of the RubCon samples is 94.8 MPa. It is shown in Figure 1.9 that the strength of the concrete samples decreases moderately regardless of the environment s humidity. After a 50-day exposure, the strength limit stabilizes and remains unchanged until the end of the test. This can be explained by low water absorption of the rubber polymer concrete, not exceeding 0.05%. 

Drying of RubCon samples does not have a significant influence on its strength and deformation parameters due to a very small quantity of the adsorbed moisture (water saturation is 0.045%). 

The tests have shown that rubber polymer concrete (RubCon) is the composite with the highest water resistance. During the exposure of the RubCon samples in... 

FIGURE 1.9 Dependence of compressive strength of rubber polymer concrete (RubCon) samples on exposition time at humidity of environment 1 50%-60%, 2 85%-95%, 3 water immersion, (From Yu. Borisov, Yu. Potapov, O. Figovsky, and D. Beilin, Water Resistance of the Polymer ConcretesJ. Scientific Israel Advanced Technology 14, no. 3 (2012) 84-91. With permission.)... 

Rubber concrete (RubCon) is a new polymer composite material created and studied by the research team of the Voronezh State University of Architecture and Construction (Russia) and the Israel company Polymate Ltd.-INRC. 

RubCon is produced using a special high-speed extruder mixer and is formed as a conventional polymer concrete with following hot dry air vulcanization (Figure 1.12). 

FIGURE 1.12 Sample of RubCon. (From O. Figovsky and D, Beilin, Building Materials Based on Advanced Polymer Matrix Review, J. Scientific Israel Advanced Technology 10, no. 3 (2008) 1-119.)... 

More detailed information about structure, properties, and manufacturing of RubCon is presented in Chapter 2. 

Development of a manufacturing process for diene oligomers belonging to a liquid rubber class with viscous liquids consistence allowed us to create a new class of conglomerate polymer composite materials—rubber concrete (RubCon). Rubber concrete is an advanced construction material created over the last few years. It is polymer concrete with a unique set of physical-mechanical, chemical, and technological properties that allow the creation of highly effective building structures and products. 

Basic Physical-Chemical and Mechanical Properties of RubCon... 

A very important time in the creation of a network polymeric composition is the choice of oligomer, because its chemical composition and structure determine characteristics of the created material. This is true also for RubCon, the liquid phase of which consists from rubbers with various microstructures of polymeric chains. Liquid rubbers in projected compositions are capable, if acted on by special sulfur-accelerating systems, to be vulcanized with formation of space-linked net polymers, the space net of which mainly determines the positive properties of the hard base of the RubCon composite. 

As several studies show, the best combination of physical, chemical, and technical parameters is exhibited by RubCon, based on diene oligomers without functional... 

In order to select the liquid rubber to use in the mixture, the durability of considered kind of RubCon was studied. For this goal, prism samples sized 40 x 40 x 160 mm were tested. 

Upper values of the durability of RubCon samples based on PBN and Ricon 130 in comparison with those of SKDN-N and Polyoil 110 are explained, in our opinion, by different molecular structures of polymeric chains of the used oligomers. As mentioned previously, rubbers SKDN-N and Polyoil 110 contain a major amount of 1,4-cis units (up to 75% of the total), while in rubbers with a mixed microstructure of PBN and Ricon 130, the unit content of 1,4-cis, 1,4-trans, and 1,2... 

Linear polybutadiene oligomers of a mixed microstructure of PBN and Ricon 130 was found to be optimal as the basic polymer for RubCon. 

Since viscosity is a very important parameter characterizing every liquid rubber and influencing the main physical and mechanical properties of the projected composite, it frequently determines the choice of the polymer and reasonability of its use. The industry manufactures rubbers with viscosity varied in large spectrum (e.g., for polybutadiene PBN, that interval is [(0.2 A 7.1) Pa - s]). However, there is no data that allows estimation of the viscosity of rubber that is useful in RubCon compositions. 

A series of experiments were carried out to evaluate the value of the viscosity of rubber allowing the needed varied parameter has been viscosity, and the measured function — the RubCon durability against compression and bending. The experiment used PBN rubber with viscosities (Pa s) of 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, and 2.2. The regression analysis of the obtained results allowed deduction of mathematical models that adequately describe the correlation of the durability of the samples to compression and bending ... 

This is probably explained by the hardness of RubCon prepared from rubber with viscosity 1.6 Pa s in comparison with that from rubber with viscosity 1.2 Pa s, because the density of linkage is higher for a polymer with higher molecular mass related to viscosity. 

Based on these results, we can conclude that the value of optimal viscosity of low-molecular polybutadiene with mixed microstructure, involved in the RubCon mixture, is in an interval from 1.1 to 1.7 Pa s. The further studies employed rubber with viscosity 1.5 Pa s. 

Liquid polybutadienes without functional groups may be vulcanized on double bonds of the diene part of the polymeric chain in the presence of a sulfur-accelerating, redox, or peroxide system. However, only the sulfur-accelerating system is able to provide the maximal durability values. Sulfur also has other advantages such as low price, availability, and so on. The amount of involved sulfur in the system depends on the desired properties of the product. For hard RubCon, this is 47-55 mass parts per 100 mass parts of rubber. 

The rising of the rate of chemical reactions between sulfur and rubber, acceleration of the vulcanization, and reduction of its temperature are accomplished using special accelerators. The use of a few accelerators may improve the vulcanization process because of their mutual activation. Two accelerators were used tetramethyl-thiuram-disulhde (thiuram-D) and CAPTAX . They act mutually and thus improve the vulcanization process and the resulting properties of RubCon. 

The previously mentioned suggestion has been tried in a two-phase experiment in which the variable parameters were the amounts of accelerators, and the value of RubCon durability as the function. 

It has been found from experience that the maximal value of RubCon durability is obtained at the CAPTAX content of 0.05 mass%, and thiuram-D 0.35 mass%. The maximum durability against compression has been found at a maximum content of thiuram-D and moderate content of CAPTAX. 

The decrease of RubCon durability at a CAPTAX content of less than 0.05 mass% is caused by the violation of accelerators complex action and appearance of chemically free rubber. Content values of more than 0.05% causes excess CAPTAX and a related decrease in durability. The increase of product durability, when the content of thiuram-D approaches 0.45% is caused by gas deliverance and pore formation in the composite volume. 

A series of RubCon samples were prepared. The content of the main components (except accelerators) was the same. The first composition used both thiuram-D... 

The change of parameters of vulcanization kinetics found in the experiment allowed more order in the composite structure, a reduction of the number of dislocations, and consequently, improvement of the mechanical characteristics of RubCon. Let us note that the optimum content of the components in the system with the additive action of accelerators for rubber of the same kind is constant for PBN it is 7 parts thiuram-D per 1 part CAPTAX. 

Planning of Activator and Calcium-Containing Components of the Composition Rubber Matrix—RubCon... 

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