The overall composition of an ethylene-norbornene-copolymer can be det
ermined by measuring the GPC-peak area, normalizing it according to sa
mple weight and using a calibration curve established on the basis of
C-13-NMR measurements. The normalized GPC-peak area decreases with inc
reasing norbornene content up to 29-30 mol% when it disappears. At hig
her norbornene contents the polarity of the signal changes but the cor
relation with norbornene content is still valid. This phenomenon is du
e to refractive index changes caused by the comonomer. GPC is therefor
e a very practical tool for characterizing COC which has recently appe
ared on the market. (C) 1996 Elsevier Science Ltd.