Browsing by Author "Delchev N."

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    COMPOSITES OF WASTE RUBBER VULCANIZATES AND MODIFIED ADHESIVE SOLUTIONS TO CREATE CONTINUOUS COATINGS
    (2021-01-01) Dishovsky N.; Delchev N.; Ivanova N.; Malinova P.; Lachev A.
    Composites of waste rubber vulcanizates and polyurethane-based adhesive solutions have been developed, containing a waste sunflower oil as a modifying additive, intended for use as seamless floorings. The floorings are made in two versions: in laboratory conditions and in real conditions. The floorings of both variants are characterized by a number of important performance parameters: mechanical properties - in terms of tension and pressure, glass transition temperature, shock absorption according to head injury criterion (HIC) and criterion for maximum value of dynamic impact of free fall acceleration (G), potential elastic energy and energy density. It was found that the most important factors for the formation of the characteristics of the composites are the size, the specific surface of the rubber crumbs, respectively, the chemical nature of the adhesive used, the amount of the adhesive solution and the amount of the modifying additive. Based on the HIC and the G criteria, it is concluded that the created seamless coating has a safe fall height of 1 meter and can be used to cover playgrounds and sports facilities.
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    Effect of the modified solid product from waste tyres pyrolysis on the properties of styrene-butadiene rubber based composites
    (2014-01-01) Delchev N.; Malinova P.; Mihaylov M.; Dishovsky N.
    Being resistant to moisture, oxygen, ozone, solar radiation, microbiological degradation, etc., waste car tyres and their deposition present a great environmental problem. Pyrolysis is an environment-friendly process for their recycling. This paper presents data referring to the study of the effect of the solid product from waste tyres pyrolysis on the properties of styrene-butadiene rubber (SBR) based composites. It is found that the further modification of the pyrolysis carbon black decreases two times the ash content and six times the zinc oxide concentration in the ash but the curing characteristics of the investigated SBR based compounds remain unaffected. The values of the modulus 100, the tensile strength and Shore A hardness of vulcanizates containing modified pyrolysis carbon black increase, while the elongation at break and the residual elongation decrease slightly. The effects observed are related to the decreased ash content of the pyrolysis carbon black following the modification as well as to the increased silicon oxide concentration in the remaining ash.
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    PERFORMANCE AND TECHNOLOGICAL MODEL FOR PRODUCTION OF SOUND- AND SHOCK-ABSORBING COMPOSITES ON THE BASIS OF WASTE ELATOMERIC MATERIALS
    (2020-01-01) Dishovsky N.; Delchev N.; Ivanova N.; Mihaylov M.; Malinova P.; Lachev A.
    The aim of the present work is to investigate the possibilities of using waste sunflower oil as a modifying additive in order to eliminate some disadvantages of polyurethane adhesives used in the production and performance of insulating composites from ground waste rubber vulcanizates. A composition and a technological model for the production of sound- and shock-absorbing composite material have been developed as a result of the present study. A positive effect of the modifying additive on the technological process and the properties of the composite materials has been established. It is attributed to the composition of the waste sunflower oil comprising different types of fatty acids. The conducted tests and the obtained results give grounds to believe that the composite material developed can find applications as a sealing element in railways of rail and tram transport, in construction for sound insulation of buildings, as well as for covering childrenā€˜s and sports grounds.