Very small diameter fibers of poly(p‐phenylene terephthalamide) (PPTA) ranging in diameter from 40nm to a few hundreds of nanometers were made by the electrospinning process. The fibers have a circular cross‐section, are birefringent and stable at temperatures greater than 400°C. Electron diffraction patterns obtained from both as‐spun and annealed fibers show meridional and equatorial reflections demonstrating order in the material. The crystal structure and morphology of the fibers were characterized using bright and dark field electron microscopy, electron diffraction and atomic force microscopy.

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Biodiesel is regarded as the most promising renewable biofuel which can satisfy the worldwide energy demand through its robust net energy output with less impact on environment and also an effective alternative or supplement for existing diesel fuel for powering Compression Ignition engines. This present study aims to compare the performance, combustion and emission characteristics of beef tallow biodiesel with its dominant fatty acid esters and their influence on these characteristics. Ethyl stearate, ethyl palmitate and ethyl oleate were identified as dominant fatty acid esters available in a composition of 14.78, 37.36 and 25.17%, respectively. Two set of samples were prepared for testing purpose and were classified as (i) blend samples and (ii) ester samples, with plain diesel as base fuel. The maximum cylinder pressure was found to be in the range between 67 and 71 bar for all the samples and heat release rate was found to be highest for B20 blend. Slight decrease in efficiency along with marginal increase in fuel consumption was a result of long chained fatty acid esters (stearate and oleate esters) whereas increase in CO 2 emission and decrease in NO X emission were because of higher oxygen content, cetane number and degree of unsaturation in the ester molecule.

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