Thermal Behavior, Structure and Morphology of Propene/Higher 1-Olefin Copolymers

Propene-based random copolymers, synthesized with two isospecific methylaluminoxane-activated ansa-zirconocenes and containing even and odd carbon-numbered higher 1-olefins, were investigated by DSC and WAXD. Nature and amount of co-units affect primary and secondary crystallization as well as melting behavior; their role is discussed in the light of microstructural features of the macromolecular chains. The specific role of 1-olefin comonomers in the development of the ?-polymorph was assessed by crystallizing selected samples at relatively high temperatures. A good agreement between the fraction of ?-phase calculated from the deconvolution of the DSC melting endotherms and from WAXD analysis was found. The ?-phase content nicely correlates with the average length of the isotactic sequences. In the WAXD patterns of some propene/1-butene copolymers a new reflection at 2? ? 10°, likely corresponding to the newly discovered trigonal modification of isotactic polypropene, was found.