PHASE-DIAGRAM AND THERMAL AND MECHANICAL-PROPERTIES OF ISOTACTIC POLYPROPYLENE HYDROGENATED OLIGO(CYCLOPENTADIENE) BLENDS

The system formed by isotactic polypropylene (iPP) and hydrogenated ol igo(cyclopentadiene) (HOCP) is investigated in order to study the infl uence of the composition and thermal history on the morphology, phase structure. miscibility and thermal and mechanical properties of the bl ends. A phase diagram presenting both the lower and the upper cloud po int curves is proposed. It is shown that these blends assume different morphologies and consequently present diverse thermal and dynamic-mec hanical behaviours depending on quenching processes from one-phase reg ion or two-phase region. From the analyses of the results of optical m icroscopy, WAXS, DSC and DMTA techniques it is found tat: blend films, quenched from the melt of one-phase region to room temperature, conta in one amorphous phase and iPP in smectic form; moreover they are tran sparent and possess a reduced permeability to oxygen and aroma; conver sely when the samples are quenched from the melt of two-amorphous phas e region there is the formation of two amorphous phases (the iPP-rich phase and the HOCP-rich phase) and at room temperature the iPP crystal lizes in the monoclinic alpha form.