Affiliation: | (1) Analytical Department, DSM Research and Patents, PO Box 18, 6160 MD Geleen, The Netherlands;(2) Present address: Fundamental Polymer Research Department, DSM Research and Patents, PO Box 18, 6160 MD Geleen, The Netherlands;(3) Present address: Trainee of the Zuidlimburgse Laboratoriumschool Sittard, Montgomerystraat 7, 6135 BW Sittard, The Netherlands |