Browsing by Author "Al-Ghamdi A.A."

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    Electrical, mechanical and dynamic properties of ternary composites from acrylonitrile butadiene rubber and conductive fillers
    (2019-08-01) Al-Sehemi A.G.; Al-Ghamdi A.A.; Dishovsky N.T.; Malinova P.A.; Atanasov N.T.; Atanasova G.L.
    This paper presents comparative investigations on dual and ternary composites based on nitrile butadiene rubber. These composites were filled with carbon black and nickel powder at various ratios with each filler or with a combination of both. The focus of this study is on the electrical, mechanical and dynamic properties of the materials as influenced by the loading rate, applied pressure and bending degree have on the specific volume electrical resistivity. The investigations of the dynamic properties view the effect that the amount and chemical nature of the fillers have on the storage modulus and the tangent of the mechanical loss angle. It has been established that the specific characteristics of each of the fillers (particle size, specific surface, tendency to aggregate and agglomerate, interaction with the elastomeric matrix) have the greatest impact on composite properties. Scanning electron microscopy studies of the fillers and composites also confirm the results obtained.
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    Influence of bis(triethoxysilylpropyl) tetrasulfide amount on the properties of silica-filled epoxidized natural rubber-based composites
    (2016-07-01) Al-Hartomy O.A.; Al-Ghamdi A.A.; Al Said S.A.F.; Dishovsky N.; Mihaylov M.
    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.
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    Influence of bis(triethoxysilylpropyl) tetrasulfide amount on the properties of silica-filled epoxidized natural rubber-based composites
    (2016-07-01) Al-Hartomy O.A.; Al-Ghamdi A.A.; Al Said S.A.F.; Dishovsky N.; Mihaylov M.
    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.
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    Properties of natural rubber-based composites containing fullerene
    (2012-01-01) Al-Hartomy O.A.; Al-Ghamdi A.A.; Al-Salamy F.; Dishovsky N.; Slavcheva D.; El-Tantawy F.
    In this study the influence of fullerenes in concentrations from 0.5 to 1.5 phr on both the vulcanization characteristics of the compounds and physicomechanical, dynamic, and dielectric properties and thermal aging resistance of nanocomposites on the basis of natural rubber has been investigated. The effect of the filler dispersion in the elastomeric matrix has been also investigated. Neat fullerene and the composites comprising it have been studied and characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). © 2012 Omar A. Al-Hartomy et al.