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A series of castor oil adducts were synthesized by esterification of castor oil with acid anhydrides: phthalic, maleic and succinic anhydrides. The chemical structure of castor oil and the prepared adducts were characterized by means of IR and 1 H NMR spectroscopy. The number-average and weight-average molecular weights were measured by gel permeation chromatography. The electrical properties were studied through the permittivity, dielectric loss and conductivity measurements, which are considered to be in the range of electrical insulation. The electrical conductivity, which describes the ionic mobility of the systems, was found to be in the range of 10 -9 to 10 -12 S/cm. This indicates that castor oil and its esters could be used for antistatic applications. The viscosity Z and the activation energy E Z , obtained from the dependency of viscosity on temperature using the Arrhenius equation, were found to increase with increasing molecular weight of the system. The effect of different concentrations of castor oil and its esters on the growth activities of the sugar beet pathogens R. solani and S. rolfsii was studied through the determination of percent germination, average length of hyphal extensions, dry mass yield and the production of sclerotia. The obtained data indicate that the esterification of castor oil with anhydrides improves the antifungal activity.

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Pluronic was modified by using maleic anhydride (MA) and was characterized by means of FTIR and 1 H NMR. Polyvinyl chloride (PVC) was blended with different contents of modified pluronic (MPL). After 20% by weight MPL, no significant change was noticed in either the electrical or the mechanical properties. The addition of 10 wt % MPL to PVC loaded with different contents of titanium oxide (TiO 2 ) and sodium bentonite was chosen to act as a dispersing agent for the two types of fillers. This result was obtained through the measurements of permittivity e 0 and dielectric loss e 00 at the frequency range (10 2 À10 5 Hz) in addition to the electrical conductivity (r). According to Arrhenius equation, the activation related to both conductivity E r and relaxation time E s in addition to the experimental r o were found to confirm the validity of compensation law for the semiconducting PVC system. The increase of e 0 and e 00 by increasing filler content in the presence of 10% MPL in comparison with those before the addition of such concentration of MPL indicates a homogenous distribution of filler in the PVC matrix. This result finds further justification through the mechanical measurements and the scanning electron micrographs.

Two maleated vegetable oils based on castor and soybean oils (COMA & SOMA) in addition to aliphatic polyester based on propylene glycol and succinic acid (PPS) were prepared and characterized by means of infrared (IR), nuclear magnetic resonance ( 1 H NMR) and thermogravimetric analysis (TGA). TGA data indicates that SOMA is more thermally stable than COMA and PPS. The electrical properties of the prepared materials were investigated through the permittivity (e'), the dielectric loss (e'') and the electrical conductivity (s) in a frequency range 10 -1 -10 +7 Hz. The obtained data were found to follow the trend COMA > SOMA > PPS. The relaxation mechanisms of such systems were also studied through the dielectric modulus M', including the real and imaginary parts (M' and M''). The effect of the prepared materials on the hydrophysical properties of the sandy soil when supplemented with different concentrations (1-5 wt %) was studied by bulk density, total porosity, water holding capacity, field capacity, hydraulic conductivity and water stability aggregates. These hydrophysical properties were improved by increasing the concentration of the added materials, which can be explained in terms of the penetration resistance in relation to friction and cohesion forces. These improvements in the hydrophysical properties of the sandy soil render it suitable for plant growth.