Ahmet T. Giz

Reaction kinetics and composition of 4‐vinylbenzenesulfonic acid sodium salt (VB)–acrylamide (Aam) copolymerization in 0.1M NaCl solution are investigated. Data obtained by the automatic continuous monitoring of copolymerization system, up to 80% conversion, are analyzed by an “error‐in‐variables method” developed for obtaining the reactivity ratios by on‐line monitoring. Monomer reactivity ratios are found as r_Aam = 0.085 ± 0.020, r_VB = 2.0 ± 0.33. Although the terminal model describes the composition data well, it is seen to be inconsistent with the reaction rates. This discrepancy is attributed to implicit penultimate effects and using the recently developed calculation method, effective radical reactivity ratios are found as s_VB = 0.26 and s_Aam = 0.027, and both composition and rate data fit the implicit penultimate model extremely well. On‐line monitored data showed that in the reactions where the VB was completely consumed, the subsequent Aam homopolymerization was very rapid; thus, the reaction showed definitely two rate regimes, before and after VB depletion. Acrylamide take up rate also showed these two rate regimes. We conclude that low conversion results can be misleading and reactions must be monitored up to a high conversion for a robust control of composition and reaction kinetics. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

PVP solutions were sonicated with high‐intensity ultrasound, and the weight‐average molecular weight was monitored by an ACOMP system. The use of continuous on‐line data to critically evaluate various models showed that the molecular weight decreased towards a limiting value. Theoretical and phenomenological models of evolution of the molecular weight during sonication are compared with the on‐line data. The Ovenall/Harrington/Madras and Giz and Tang models werer found to describe the results adequately. These models share the property of an initial rapid drop in molecular weight followed by a slowing down of the rate of molecular weight decrease. magnified image