No abstract

The density and volume of four Indian edible vegetable oils, sunflower, rice bran, groundnut and coconut, and one Indian nonedible oil, castor oil, have been experimentally determined. The values obtained were used to estimate the volume expansivity a, hence the thermoacoustic parameters, such as the Sharma constant S~ the isochoric temperature coefficient of internal pressure ~] v, the isochoric temperature coefficient of volume expansion Jr, reduced volume I~, reduced compressibility ~ and the Huggins parameter F. The results obtained show that the Sharma constant So has the same characteristic value of 1.11 ___ 0.01 for the five oils, thus establishing the constancy of the Sharma parameter. All the other parameters are of the expected order of magnitude; however, in all cases there is a uniform deviation at 293~ which can be attributed to the behavior of density and volume at this temperature.KEY WORDS: Density, Huggins parameter, isochoric temperature coefficient of internal pressure, isochoric temperature coefficient of volume expansion, physicochemical properties, reduced compressibility, reduced volume, Sharma constant, vegetable oils, volume expansivity.

SYNOPSISKinetic studies were carried out on the reaction between dimer acids and diethylenetriamine (DETA) and triethylenetetramine (TETA) in melt phase. The reactions were performed at temperatures in the range of 145" to 190°C and followed by determination of the acid and amine values of the intermittent products. The polyamidation reactions of C36 dimer acids and DETA and TETA followed overall second-order kinetics and had activation energies of 14.4 kcal/g mol and 12.3 kcal/g mol, respectively.

From the volume expansivity c~, a number of thermoacoustic parameters, including the Sharma constant, So, are estimated for four fatty acids as a function of temperature. The Sharma constant, which was established to be a constant with the characteristic value 1.11 _ 0.01 over a number of systems investigated by earlier investigators, is also found to be a constant with the same value for all fatty acids under investigation. Further, the Sharma constant, So, is independent of temperature and dependent only on c~. All other parameters estimated are discussed and compared with the values reported in the literature by earlier workers for different systems.JAOCS 72, 1537-1540 (1995).

SynopsisKinetic studies were carried out on the reaction between ethylenediamine and dimeric fatty acids in melt phase. The reaction was performed at 124, 130, 145, 160, 174, and 190°C and followed by determining the acid value of the product. The polyamidation reaction was found to be of overall second order with an activation energy of 18.2 kcal/g mol up to 90% conversion and of overall third order with an activation energy of 16.4 kcal/g mol above 90% conversion.