Browsing by Author "Mitkova F."

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    Studies on natural rubber based composites filled with products from renewable resources with improved adhesion to icy surfaces
    (2018-01-01) Dishovsky N.; Mitkova F.; Angelov Y.; Kandeva M.; Vladimirova L.
    Slips and falls on icy surfaces can cause serious injuries of people. The primary risk factor for slipping incidents is undoubtedly the decreased friction coefficient between the shoe sole and the ice or snow surface. Nowadays environmental protection has been gaining significance and becoming highly important for the various innovation strategies. In rubber industry the concept of environmental protection is more often associated with the maximum use of elastomers and ingredients from renewable sources in the manufacture of rubber products. The aim of this work is to investigate the possibilities of using elastomers and ingredients from renewable sources - natural rubber, silica obtained by rice husks incineration and microcrystalline cellulose - as fillers and rapeseed oil as a process additive in compositions, intended for the manufacture of soles for winter footwear having an increased coefficient of friction to various types of icy surfaces. Dynamic mechanical thermal analysis has been used to predict the adhesion of the materials to ``dry ice``, ``wet ice`` and melting ice. It has been found that, in all the cases examined, the composites containing natural rubber and a combination of microcrystalline cellulose (20 phr) and silica (40 phr) as fillers are the most suitable for the purpose. The silica used can be both synthetic and from renewable sources. The tribological tests carried out have confirmed these composites under the conditions of ``dry ice`` and ``wet ice`` fall into the class of the highest resistance against slip but on melting ice they do not have the necessary degree of resistance. It is believed that the use of a polar elastomer and hydrophobilizing the surface of microcrystalline cellulose particles will solve the problem.