Structural, Densimetric, and Thermal Properties of Biodiesel and Diesel Blends.

Binary blends of both commercial petrodiesel and biodiesel were prepared and characterized at room temperature. Petrodiesel-type ultralow sulfur with a Sulfur level of 10 ppm/kg called S10 was used, while biodiesel was a methylic one synthesized via soybean oil and methanol, with a composition based on a mixture of several molecules-type fatty acid monoalkyl esters. A set of 10 binary blends containing 0 to 100% biodiesel were prepared by conventional mixing of volumetric fraction of components. The structural characterization of blends was carried out by attenuated total reflection Fourier transform infrared spectroscopy, ATR-FTIR, in the Mid region. Volumetric properties of the blends were measured via the pycnometry technique. Thermal conductivity was investigated via a digital thermal conductivimeter, using a two-needle sensor. Infrared spectra of all blends exhibited a significant shifting of the position of the characteristic absorption band of biodiesel, a specific vibration of the charged head assigned to esters groups. Values of parameters intensity, area, and specific absorption bands of diesel and biodiesel and volume of each blend, as well as thermal conductivity, undergo changes as a function of biodiesel fraction in the mixture. Evolution of parameters mentioned as a function of the biodiesel fraction in the blend was assigned to the molecular interaction between the molecule components of the mixture. In addition, these values do not obey a linear simple mixture rule. However, the set of structural, densimetric/volume, and thermal data of binary blends show the development of Excess phenomena properties that are associated with liquid cohesion. Based on the secondary chemical bond concept, the properties of Excess were discussed.