Macromolecules, Vol.27, No.20, 5863-5870, 1994
Detailed Kinetic-Analysis of the Radical Polymerization of Trans-4-tert-Butylcyclohexyl Methacrylate in Benzene Based on the Rate Constants Determined by Electron-Spin-Resonance Spectroscopy
The radical polymerization of trans-4-tert-butylcyclohexyl methacrylate (4BCHMA) in benzene at 60-degrees-C was kinetically analyzed in detail. The propagation and termination rate constants (k(p) and k(t)) were determined by means of electron spin resonance spectroscopy in several polymerization systems, at various initiator and monomer concentrations in the absence or presence of a viscosity modifier and a chain transfer agent. The aftereffect was also analyzed during the polymerization with a photoinitiator to evaluate k(t). We obtained a constant k(p) (570 +/- 10 L/(mol-s)) irrespective of the polymerization conditions, whereas k(t) was (0.5-2.3) x 10(6) L/(mol.s) depending on the viscosity of the polymerization medium and the chain length of the propagating radical. It has been revealed that k(t) is proportional to the -0.28 power of the chain length when it was evaluated in the polymerization systems including negligible viscosity effects. The reaction orders with respect to monomer and initiator concentrations in the polymerization rate equation are discussed.
Keywords:TERMINATION RATE CONSTANTS;CHAIN-LENGTH DEPENDENCE;ABSOLUTE RATE CONSTANTS;METHYL-METHACRYLATE;DIMETHYL 2;2’-AZOBIS(ISOBUTYRATE);EMULSION POLYMERIZATION;ANALYTICAL EXPRESSION;RATE COEFFICIENTS;PROPAGATION;PARAMETERS