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ملخص:
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Theaim of the work is to study mainly the dielectric constant of somemembers of the amide group with a special reference to the effect ofdifferent concentrations with water, variation of the temperature, andthe effect of neutron irradiation, at a frequency of 3 MHz. Moreover atthe same time we studied the dielectric constant of neutron irradiateddiala-shell B-oil. The dielectric values were determined at varyingfrequencies keeping the temperature, however aa fixed, This work isrepresented in two parts.
Part I;
1- We study the dielectricconstant of the amide group, which contains: IMA, NMF, DMA and IMP. Thisgroup was so chosen as, due to its different properties. For example, JJMA and KMF are protic solvents which contain free hydrogen atoms, while the others, IMA and IMP, are Aprotic with uq free hydrogen atoms.
Moreover, the effect of polarity of the solvent has been considered,THF was selected as a nonpolar solvent.
Thesolutions of our solvents with the conductivity water were prepared tostudy the effect of the polarity of the amide group on the polarity ofwater; furthermore the effect of polarity of water on the nonpolarsolvent (THP),2- The used organic solvents, as well as the conductivitywater were prepared in pure states.
3- The solutions ware obtainedby adding the adjusted amount of water to the different percent ageaweights from 10 up to 100 wt$ for solvents in steps of
4- The dielectric constant ( €. ) and the loss factor (tan o ) for these solutions were also measured at a fre-
quency of 3 MHz and at range of temperature from 5 to
o
60 G in steps of 5 degrees. The temperature was controlled
o
by a thermostat to + 0.5 G.
5- The data obtained from our measurements ?irere in a good agreement withprevious published results. The lowing table summarises the comparison:
6- It is found tjiat the dielectric constants of the solutions of thesesolvents with water obey fairly the additivity rule? which states thatthe addition of a substance of higher dielectric constant to one oflower permittivity, would give a mixture with higher dielectricconstant than that of the second component. Excluded is the mixture ofEMA with water at certain
concentrations and temperatures which deviate from that
o rule. As an example, at temperature 35 C, the concent-
ration20 wt/S of 1MA, has a dielectric constant 170; at the same temperature^ the dielectric constant of pure water and pure HMA are 74.8 and 165respectively.
7- The dielectric constant (C) of the previous solution were found to obey the following relation;
€
- bT a e
where a and b are constants and T is th© absolute temperature•
Exceptionsare the solutions of 1MA and NMP with water; for which tha aboverelation did not obeyed; within the considered temperature range*
8- The dielectric constant of pure HMA has a transi-
o tion at the melting point 28 C. This phenomana, can be
observedfor individual polar matter, having a distinct melting point. There ajump-like changa in dielectric constant (€) during metling can beobserved. As an example, the dielectric constants of MA at temperatures
o
20 and 28 Q were 34 and 172 respectively. This can be attributed to thefact that at melting point, the specific volume increases sharply, which create space that is required for rotation of the permanent dipolemoment in the direction of the field.
9- The loas factor (tan£) wasmeasured for BMAjPHF, THP and their mixtures with water at differenttemperatures. The loss factor (tan£) increases by increasing thetemperature, this can be attributed that by raising the temperature, themobility of free electrons increases. The loss factor ofmonosubstituted amides with water is so high that the attainableequipment cannot measure it satisfactorily.
10- The electric conductivity of the solutions was found to obey the following relationship:
A e
where T s the absolute temperature.
kt> * Boltsmann’s constant.
a
* The activition energy,11- The study of the variations of the dielectricconstant (C)t the loss factor (tan$) and the electrical
conductivity of the mentioned solutions y?ith the concen~
/ ° trations and at a constant temperature(chosen at 25 C).
It was found that, the dielectric constant (£), for mix-
o tures of DMA, BMP and IHP with water at 25 G decreases by
increasingthe wt$ of these solutions. While in case of UMA and HHF, thedielectric constant increasing by increasing of the wt$ of the solventin solution. This can be attributed to the fact that the dielectricconstant of monosu-bstituted amides is greater than that of theciisubstituted amides. Also the monosubstituted amides (protic) havefree hydrogen atoms vsfaich associate molecules of water more readilythan di^ubstituted amides (Aprotic).
The loss factor (tanS) at 25 C, for the disubstituted amide has a maximum value at a difiniteconcentration, for example, the solutions of DMA, BMP and THP with wateryield a maximum value at concentrations 165, 56 and 40 wt$ of thesesolvents respectively.
The electric conductivity of these solutiondepends mainly on the loss factor, and the curves show the same shape asin the case of the loss factor (tan S). The electric conductivity ofthe pure solvents decreases in the following direction H20 « 1.84 x 10~6^ DMA = 1.2 x IC DMP » 1.1 x 10”*6^> THP = 0.08 x 10~6. Aluo thedielectric
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