Facile synthesis of ethylene-propylene fully alternating copolymer and comparison with random copolymer of similar composition

A precisely sequenced ethylene-propylene (EP) fully alternating copolymer was synthesized via trans-1,4-polymerization of isoprene catalyzed by Ziegler-Natta catalyst followed by hydrogenation. This EP copolymer was used as model polymer for studying structure-property relationship. An ethylene-propylene random copolymer (ethylene-propylene rubber [EPR]) with similar ethylene content was also prepared for comparison, and the effect of comonomer sequence distribution on properties was investigated. The copolymer chain structures were monitored by H-1 and C-13 NMR and Fourier translation infrared. Differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, and tensile tests were employed to determine the thermal and mechanical properties. The fully alternating copolymer EP gives a more precise glass transition comparing than EPR. Further understanding on thermal properties and aggregation behavior of ethylene-propylene copolymers is made possible by this comparative study. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45816.