| Abstract: | A method for the determination of degree of branching, much faster than the one previously used, is described. A sample cell designed for fast introduction and removal of samples is used and the method for measuring band intensities has been adapted to computer use. It is shown how the degree of branching decreases from the first member of a series of extract waxes to the residue, because of the higher solubility of isoparaffins compared with that of n-paraffins. A linear relationship between crystallinity and degree of branching was found to exist for the series. Fischer-Tropsch ‘medium wax’ exhibits an abnormally low crystallinity. Possible causes for this are the fact that it has a much lower average molecular weight than the extract waxes, which were derived from ‘hard wax’, and that there can be differences in chain-length distribution. The extract waxes were found to contain 4–6% more amorphous material than isoparaffins, as determined by urea adduction. This difference is explained in terms of the tendency of the urea method to give too low values, the fact that some normal molecules can be present in amorphous regions and the uncertainty of the significance of infra-red crystallinity in absolute terms. |
