A. Farha Al Said

Controlling of conduction mechanism and electronic parameters of silicon–metal junction by mixed Methylene Blue/2′-7′-dichlorofluorescein

Abstract Al/p-Si junction based on Organic Mixed Layer (OML) Methylene Blue (MB) and 2′-7′-dichlorofluorescein (DCF) was fabricated and the current–voltage ( I – V ) and the capacitance–voltage measurements of the structure have been obtained at room temperature. This combination resulted in both a good rectifying behavior and low leakage current. The characteristic parameters of the structure such as barrier height, ideality factor, interface states density and series resistance were determined from the electrical measurements. Also, Cheung functions and Norde method were used to evaluate the I – V characteristics and to obtain the characteristic parameters of the Schottky contact. High-low frequency capacitance–voltage characteristics have been observed to have a maximum. The maximum value of the capacitance is decreased with increasing frequency. The higher values of capacitance at low frequencies were attributed to interface states and the excess capacitance resulting from the interface states in equilibrium with the Si that can follow the alternating current signal. The J – V curves in the reverse direction are taken and interpreted via both Schottky and Poole–Frenkel effects. Poole–Frenkel effect was found to be dominant in the reverse direction.

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.

Effect of carbon–silica dual phase filler obtained by impregnation method on the properties of SBR-based composites

Styrene butadiene rubber (SBR)-based composites have been reinforced with carbon–silica dual phase fillers. The new type of reinforcing fillers have been obtained by an impregnation method used for introduction and deposition of a second silica phase over the surface of carbon black particles. The mechanical properties of SBR-based composites (applicable for passenger tread compounds) have been investigated. It has been found that the modulus at 100% of elongation and tensile strength of the composites reinforced with the dual phase fillers have increased considerably in comparison to those of the composites containing standard carbon black.

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.