Kinetics and modeling of free radical polymerization of N-vinylformamide

Free radical polymerization kinetics of N-vinylformamide was investigated i n bulk and in aqueous solution. The molecular weight development with N-vin ylformamide conversions was measured using a gel permeation chromatography (GPC). The bulk process showed a typical "gel effect" from the beginning of the polymerization. The molecular weight increased steadily at low convers ion and leveled off at high conversion. In the solution polymerization, the "gel effect" became less pronounce with decreasing monomer concentration. When the monomer concentration was less than 40 wt%, no auto-acceleration w as observed from the time-conversion curves. The k(p)/k(t)(1/2) values of t he polymerization system were determined using the initial rates of bulk po lymerization and the number average molecular weight data at 50, 60 and 70 Z degreesC. A kinetic model based on free volume theory was proposed to des cribe the polymerization kinetics and molecular weight development. The mod el agreed with the time-conversion and conversion-average molecular weight data. (C) 2001 Elsevier Science Ltd. All rights reserved.