propagating polymer radical
Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Abstract The polymerization of di-2[2-(2-methoxyethoxy)ethoxy]ethyl itaconate (1) with dimethyl 2,2′-azobisisobutyrate (2) was studied, in benzene, kinetically and spectroscopically with the electron paramagnetic resonance (EPR) method. The polymerization rate (R p) at 50°C is given by the equation:R p=k0.48 2.4. The overall activation energy of polymerization was calculated to be 34 kJ·mol−1. From an EPR study, the polymerization system was found to involve EPR-observable propagating polymer radicals of 1 under the actual polymerization conditions. Using the polymer radical concentration, the rate constants of propagation (k p) and termination (k t) were determined. With increasing monomer concentration,k p(1.5∼4.3 L·mol−1·s−1 at 50°C) increases andk t (1.0·104∼4.2·104 L·mol−1·s−1 at 50°C) decreases, which seems responsible for the high dependence ofR p on the monomer concentration. The activation energies of propagation and termination were calculated to be 11 kJ·mol−1 and 84 kJ·mol−1, respectively. For the copolymerization of 1(M 1) and styrene (M 2) at 50°C in benzene the following copolymerization parameters were found:r 1=0.2,r 2=0.53, Q1=0.57, ande 1=+0.7.
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