Dielectric properties of different varieties of rapeseed-mustard oil at different temperatures

Dielectric properties of five rapeseed-mustard oil samples having different percentage of erucic acid have been Studied at 100 kHz, 9.93 GHz and optic al frequency or sodium light. The dielectric constant at optical frequency (epsilon (infinity)) is almost the same for all the five samples, while the dielectric constant at 100 kHz (epsilon (0)), the dielectric constant at 8 .93 GHz (epsilon ') and the loss factor (epsilon ") show dependence on eruc ic acid content, but no systematic variation with change in erucic acid is obtained which may be attributed to the presence of other fatty acids in th ese samples. Temperature variation of dielectric properties has also been i nvestigated in the range 303 to 333 K. epsilon (0) and epsilon (infinity) d ecrease regularly with increase in temperature, while epsilon ' and epsilon " do not show a regular variation with temperature. except for Hyola-401, which contains zero level of erucic acid. In other samples epsilon ' and ep silon " show a maximum or minimum type of behaviour at about 313 K. which m ay be attributed to the presence of some type of molecular resonance/antire sonance at this temperature. The molar free energy of activation, (DeltaF(e psilon)) and the macroscopic relaxation time (tau (m)) have also been worke d out whose temperature dependence requires consideration of other fatty ac ids also.