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On the basis of recently developed numeric procedures, the results obtained for the propagation constants kp by means of the PLP-SEC method (pulsed laser polymerization followed by size exclusion chromatographical analysis of the chain length distribution) were subjected to a critical reevaluation and reanalysis particularly with respect to the chain length dependence of k p. In this context the errors arising from a broadening caused by axial dispersion in the SEC were largely eliminated together with other uncertainties in assessing the characteristic chain length L 0 on which the evaluation of kp is based. The main result that refers to the bulk polymerization of methyl methacrylate and styrene in the temperature range 25-70 °C is that the previously found negative long-range chain length dependence of k p survived this procedure to an extent that widely exceeds the known variation of kp for extremely short chains and extends over a range of several hundreds of propagation steps.

Cover:The picture on the cover shows theoretical PLP-SEC-distributions (characteristic parameters as indicated) assuming various extents of axial dispersion (small: red; moderate: green and large: blue).

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