Propylene-vinylcyclohexane copolymers: Synthesis, properties, and oxidation of polymers

Abstract

Propylene-vinylcyclohexane copolymers containing 0.02–0.37 mol % vinylcyclohexane are synthesized and characterized; the copolymers are prepared via bulk copolymerization at 60°C in the presence of a metallocene catalyst with the C2 symmetry rac-dimethylsilylidene-bis(2-methyl-4-phenylindenyl)zirconium dichloride activated by polymethylaluminoxane. The reactivity ratios are calculated to be 26.6 for propylene and 0.025 for vinylcyclohexane. The introduction of vinylcyclohexane into PP slightly affects the stereoregularity of the polymer chain but markedly decreases its molecular mass and changes the thermophysical and mechanical characteristics of the polymer. The oxidation characteristics of the prepared copolymers are estimated: The induction period of oxidation is determined from oxygen absorption, and the termination-rate constants of peroxide macroradicals is determined from the chemiluminescence of copolymers. The dependence of the kinetic characteristics of oxidation of the copolymers on the content of side cyclohexyl groups is found, and the possible mechanisms of oxidation of copolymers are considered.