Mihail Mihaylov

Influence of Carbon Black Structure and Specific Surface Area on the Mechanical and Dielectric Properties of Filled Rubber Composites

Natural rubber based composites have been prepared using various amounts of two fillers: conventional Corax N220 carbon black or electrically conductive carbon black Printex XE-2B which has a very high specific surface area. The composites have been studied by dynamic mechanical thermal analysis, dielectric thermal analysis and SEM. It has been established that all vulcanizates investigated are in the glass state in the C to C interval. The storage modulus increases with the increasing filler content in the C to

Effect of the Carbon-Silica Reinforcing Filler Obtained from the Pyrolysis-Cum-Water Vapour of Waste Green Tyres upon the Properties of Natural Rubber Based Composites

The aim of the present paper is to investigate the solid product (SiO2D, pyrolysed silica filler) obtained via pyrolysis-cum-water-vapour of waste “green” tyre treads as a reinforcing filler in natural rubber based composites. Curing characteristics, mechanical and dynamic properties of the investigated composites comprising a pyrolysed silica filler have been compared to those of the vulcanizates comprising conventional carbon black, silica or their blends. The mechanical and dynamic properties of the studied composites show that the product discussed could by all means replace the conventional fillers – carbon black, silica as well as their blends – in natural rubber based composites. Indirectly, the results obtained allow the conclusion that the product obtained from pyrolysis-cum-water vapour of waste “green” tyre treads is not a pure mechanical blend of the fillers used for the production of “green” tyres (silica and carbon black). Though some amounts of silica and carbon black are present in the product, it also contains silica with carbon deposited on its particles surface resulting from the destruction of elastomer matrix. That makes this product similar to the dual phase fillers described in literature.

Influence of carbon black/silica ratio on the physical and mechanical properties of composites based on epoxidized natural rubber

The aim of the present paper is to investigate how carbon black/silica ratio influences the curing characteristics, mechanical and dynamic properties of composites based on epoxidized natural rubber (Epoxyprene 25). The data obtained show that the composites, containing carbon black and silica at a 30:40, 20:50, and 10:60 ratio have the best complex of parameters (cure characteristics, mechanical and dynamic properties). That is probably due to the intermingling of carbon black and silica particles what leads to the formation of hydrogen bonds between the silanol groups of silica particles. As a result, silica particles aggregate less and the filler disperses better in the rubber matrix. On the other hand, the presence of a silane coupling agent and the polar character of epoxidized natural rubber predetermine the stronger polymer–filler interaction.

Influence of matrices chemical nature on the dynamic mechanical and dielectric properties of rubber composites comprising conductive carbon black

The study presents the effect that elastomeric matrices different in their chemical nature (a non-polar and crystallizing natural rubber and a polar and non-crystallizing acrylonitrile-butadiene rubber) have upon the dynamic mechanical and dielectric properties of the composites comprising different amounts of conductive carbon black. Dynamic mechanical thermal analysis (DMTA) and Dielectric thermal analysis (DETA) are the techniques used for studying the structure-properties relationships of the composites. The experimental results show that the matrices studied and their specific properties have a great impact upon both the dynamic mechanical and dielectric parameters of the composites based on them. The chemical nature, structure and specific characteristics of the matrix affect the storage modulus, glass transition temperature, elasticity behavior, high-elasticity, energy dispersion, dielectric permittivity and DETA tan δ of the composites investigated. The matrix effect dominates at lower filler amounts and determines the properties of the composites.

Dynamic mechanical thermal analysis and dielectric thermal analysis of siloxane rubber-based composites filled with carbon black

Siloxane rubber-based composites filled with furnace carbon black N 220 at various concentrations were investigated bydynamic mechanical thermal analysis and dielectric thermal analysis. It was found that in the temperature interval from−30°C to 100°C the increase in the amount of carbon black results in the increase in the storage modulus (E′) values, as well as those of the mechanical loss angle tangent (tan δ). The decrease in E′ and the increase in tan δ in the interval from −40°C to −30°C was due to the process of the melting of the crystal structure of the siloxane rubber, formed during the cooling of the tested samples. Dielectric thermal analysis showed that the increase in the amount of carbon black lead to obtaining of vulcanizates with higher dielectric permittivity (ε′), whose values decrease with the increase of frequency. The research that was carried out showed that with the siloxane rubber-based composites the percolation threshold was reached when the concentration of carbon black was 20 wt%.

Comparison of the Dielectric Thermal Properties and Dynamic Mechanical Thermal Properties of Natural Rubber-Based Composites Comprising Multiwall Carbon Nanotubes and Graphene Nanoplatelets

The aim of the present study is to obtain natural rubber-based composites with optimal conductivity at a lowest possible filler amount. For this reason, two different conductive nanoparticles—multiwall carbon nanotubes and graphene—have been used at different amounts. The dynamic and dielectric properties of the rubber composites have been investigated and compared. The results reveal improvement in the dielectric permittivity of the composites with the increasing amount of MWCNTs. The percolation threshold is reached and surpassed when MWCNTs concentration is over 6 phr. The dielectric permittivity of the composites comprising GNP does not change considerably as dependent on the filler amount. At the concentrations chosen those samples are considered to be dielectrics. The data from the mechanical thermal analysis show that polymer-filler interaction in the composites comprising MWCNTs is stronger than that in composites filled with GNP. That fact is an evidence of the better reinforcing effect produced by MWCNTs.

Investigation on the Influence of Various Kinds of Soaps on the Mechanical Properties of Silica Filled Composites Based on Natural Rubber

The aim of this study was to investigate the influence that different fatty acid zinc salts had on the rheological, curing and mechanical properties of natural rubber based composites filled with silica and containing bi-functional organosilanes in the presence or absence of zinc oxide. The results demonstrated that the combination of zinc oxide and zinc soaps had a strongly pronounced anti-reversion effect. The absence of reversion in the cure curves of the rubber compounds comprising a combination of zinc oxide, stearic acid and zinc soaps, results in retention of their mechanical properties, even after overcure.

Influence of bis(triethoxysilylpropyl) tetrasulfide amount on the properties of silica-filled epoxidized natural rubber-based composites

Abstract The aim of the present article is to investigate the influence of the amount of bis(triethoxysilylpropyl) tetrasulfide on the curing characteristics and mechanical and dynamic properties of rubber composites based on epoxidized natural rubber (Epoxyprene 50) filled with 70 phr silica. The obtained results showed that although the interaction between the epoxy groups of epoxidized natural rubber and the silanol groups of silica through hydrogen bonds improves the dispersion of filler in the rubber matrix, the presence of silane coupling agents is necessary to obtain rubber compounds and vulcanizates with good vulcanization characteristics and mechanical and dynamic properties.