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Verzeichnis derThe molecular weight distribution including the calculation of M n, M~ and M z of polyacrylamide in aqueous 0.1 M sodium sulphate-solution has been determined by simultaneously and continuously monitoring the effluent from a size-exclusion chromatographic (SEC) column filled with porous glasses with a low-angle-laser-light-scattering (LALLS) photometer. The recorder traces of the scattering intensity and the refractive index difference have been digitalized in about 400 steps corresponding to 200 #1 fractions. Each fraction has been assumed to be monodisperse. This method gives absolute data rather than relative data obtained from any calibration method. The investigations clearly show a flow-rate dependent degradation of samples with relatively low molar masses (M~ = 500 000 g/mol at MJM n = 2.5) at typical flow rates Q -> 1 ml/min. A discussion of some problems encountered using aqueous SEC and a way to determine the critical molar mass, below which no degradation could be observed, based on elongational flow theories is given.

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Petroleum reserves are diminishing at a faster rate and the world is facing twin crisis in fossil fuel depletion and environmental degradation owing to extensive use of fossil fuel. Finding viable and sustainable alternative fuel is crucial for the world at large and especially for oil importing countries like India. In the present work, biodiesel is produced from tamanu oil, which is non-edible, plentiful, and cost effective. However, the viscosity is high which demands a two stage esterification to reduce its fatty acid content within the limits for automotive applications. Due to interactive effects among the process parameters, design of experiments is employed for optimization. It was observed that methanol and catalyst concentration are the major influencing process parameters, whereas time and temperature have insignificant role on acid value reduction and percentage of oil yield. The extracted biodiesel was tested for fuel properties with standard test procedures and found to be in compliance with ASTM standards.