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Name: Mona Amin Hasan Saied.
Date of Birth: 22-12-1973
Nationality: Egyptian
Previous Degrees: B.Sc.
Registration Date: 27/3/2005
Supervisors: 1- Prof. Dr. Wafaa M. A. Khalil .
2- Prof. Dr. Maher Z. Elsabee’.
3- Prof. Dr. Kamal N. Abdel-Nour.
Examiners: 1- Prof Dr Bernhard Stoll,
2- Prof. Dr. Wafaa M. A. Khalil .
3- Prof. Dr.Mohamed E. Al Gohary.
Title of Thesis : Study of some biophysical properties of castor oil and some
of its adducts and its effect on different types of micro-organisms.
Key Words: Castor oil, Adducts, micro-organisms. SUMMARY
Castor oil is a biodegradable material used in medical applications in addition to its uses as electrical insulator. Its structure is of special nature which promotes various reactions in which the esterification is considered to be one of the most important reactions. Castor oil was esterified by some acid anhydrides : phthalic, maleic and succinic anhydrides aiming to find out the capability of using such products as electrical insulators as well as bioactive materials. In addition to study the physical properties on diluting with propanol.
Chapter I comprises an introduction and literature survey of castor oil and some of its prepared adducts to be used as electrical insulators in addition to its medical applications.
Some certain aspects of dielectric behaviour in simple terms and equations relating the various phenomena to molecular parameters are presented in chapter II.
Chapter III deals with the experimental work which starts with materials under investigation: castor oil and the method of preparation of the new adducts obtained by esterification of castor oil with phthalic, maleic and succinic anhydrides. A brief description of the instruments used together with accuracy of measurements are also given in this chapter.
Results and discussion are given in chapter IV. The first part of this chapter deals with characterization of castor oil and its prepared adducts by means of FTIR and 1H NMR spectroscopy in addition to the molecular weight determinations by gel permeation chromatography (GPC). The electrical properties of the investigated materials were studied through the permittivity έ, dielectric loss ε˝ and conductivity measurements. The data of έ and ε˝ given for castor oil and its investigated esters
which were carried out at different frequencies indicate that both parameters follow the order CO+MA > CO+PA > CO+SA > CO .
The analysis of the absorption curves relating ε˝ and log f was done in terms of superposition of Fröhlich and Havriliak-Negami functions in addition to the conductivity term. The low frequency region which is fitted by Fröhlich function with distribution parameter ( P = 3 ) with relaxation time τF in the range of 4.5x10-4 s ascribes Maxwell-Wagner effect due to the multi –constitutes of the investigated systems. The second region in the higher frequency range which was fitted by Havreliak – Negami function with relaxation time τHN could be attributed to the mobility of the main chain including the attached groups. The value of τHN was found to follow the sequence CO+ PA > CO+SA > CO+MA > CO depending on the molar volume of the investigated material.
The electrical conductivity σdc for such materials was calculated and found to follow the trend CO+MA > CO+PA > CO+SA > CO. This trend was found to be in good agreement with that of the activation energy E calculated from the dependency of the conductivity on temperatures.
On the other hand, the range of conductivity found for either castor oil or its esters at different temperatures (10-9 - 10-12 Scm-1 ) indicates that these materials could be used for the insulation purposes i.e. antistatic applications.
The viscosity measurements as well as the activation energies which were determined from the dependency of the viscosity on temperature follow the order CO+PA > CO+MA > CO+SA > CO depending on the molecular weight of the material.
The antifungal properties of castor oil and its esters on the growth activities of the sugarbeet pathogens: R. solani & S. rolfsi was investigated. The percent germinantion (G%), the hyphal extension ( lh μm ) , dry mass yield ( Dm mg ) and the number of sclerotia produced per plate were found to decrease with increasing the concentration of either castor oil or castor oil esters from 25-200 μg ml-1 reaching zero as no sclerotia were produced as compared with the control. On the other hand
the antifungal activity for such investigated materials was found to follow the order CO+SA< CO+MA < CO+PA < CO, as CO+SA is considered to be the best among the investigated esters rather than castor oil itself.
As castor oil and its esters possess very high viscosities, so, it was interesting to study in detail the above properties when mixed with low molecular weight alcohols such as propanol. This study is given in the second part of chapter IV. Castor oil was dissolved in 1and 2-propanol while castor oil esters were dissolved in 1-propanol.
The data of έ and ε˝ which were carried out at frequencies from 100 Hz up to 100 kHz indicate that both parameters increase by increasing the mole fraction of propanol in the mixture. By increasing temperature from 30 to 60 0C, έ was found to decrease untill certain concentration after which έ starts to increase while ε˝increases continuously by increasing the temperature. The decrease in έ was discussed in terms of the decrease in density and the randomness of the dipole orientation . The opposite trend was noticed at 0.9 mole fraction of propanol and at frequency less than 1 kHz and it was discussed in terms of the high conductivity of propanol .
The electrical conductivity of such materials was also studied. At certain concentration of propanol (~ 0.8 mole fraction ) castor oil and its phthalic and succenic esters, loose to some extent their insulating properties while castor oil esterified with maleic anhydride could loose its insulating properties at lower concentration (~ 0.65 mole fraction ) due to the higher conductivity of maleic anhydride (1x10-10 S cm-1 at 30 0C ) in comparison with those for castor oil and its esters with phthalic and succinic anhydrides (1.2 x 10-12 , 6.7 x 10-12 and 3 x 10-12 ) respectivly .
The activation energy Eσ which was obtained from the dependency of the electrical conductivity on temperature indicate that Eσ decreases by addition untill 0.9 mole fraction of propanol after which Eσ increases reaching that of propanol. This result could support the data given in the case of permittivity measurements. The variation
of viscosities nearly do not vary with the type of the alcohol and Newtonian behaviour was observed in all cases. The activation energy Eη obtained from the dependency of viscosity on temperature shows some decrease by increasing the mole fraction of propanol. This decrease starts slowly until 0.8 mole fraction after which a sharp decrease was noticed . At this concentration, it seems that the viscous flow starts to loose to some extent the restriction motion which is expected to take place at the lower concentrations. This trend is comparable with that found in the case of density measurements when plotted graphically versus the mole fraction of propanol in the mi
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