COMPENSATING THE COMPOSITION DRIFT IN REACTIVITY RATIO CALCULATIONS FOR COPOLYMERIZATIONS CARRIED TO HIGH CONVERSIONS

The effect of composition drift on the accuracy of linearised methods of determining the reactivity ratios in copolymerization reactions is calculated. It is shown that, when the reactivity ratios differ widely , even at a very low conversion of 5% the drift causes large errors in the ratios found with these methods. However, by using an appropriate average of the initial and the final monomer ratios, the errors due t o the composition drift can be significantly reduced, so that linearis ed methods with averaging can be used with confidence at moderate (30- 50%) conversions.