Kinetics of Azo-Initiated 1-vinyl-2-pyrrolidone Polymerizations at Low Conversions in Aqueous Media

摘要

The free-radical polymerization behavior of 1-vinyl,2-pyrolidone (NVP) was studied at low conversions, using capillary dilatometry, The aqueous media were kept at neutral pH and the studies were conducted isothermally, at 40 or 45degC. The azo-type initiators used were 4,4′-azobis-4-cyanopentanoic acid (ACPA), 2,2′-azo-bisisobutyronitrile (AZBN), and 2,2′-azobis[2-(2-imidazolin-2-yl)propane dihydrochloride] (ABDH). The monomer concentration and initiator concentration ranges were 1.17-1.24 mol L~(-1) and 1-8 mmol L~(-1), respectively. The rates of polymerization (R_p) and orders of reaction with respect to NVP and the initiator were evaluated and the kinetic equations were found to be R_p (propor.to)[NVP][ACPA]~(1.2) (propor.to)[NVP][AZBN]~(1.1), and R_p (propor.to)[NVP]~(2.2)[ABDH]~(1.1). The polymers obtained were characterized by their viscosity numbers and correlation of the viscosity average molecular weights made with the type and amount of the azo initiator.