New Trends in the Field of Propylene Based Polymers

Abstract

This paper deals with the high degree of control of the intimate structure of polymers obtained with Ziegler–Natta (Z-N) catalysts. In the field of the poly(α-olefin)s, there are Z-N catalysts able to produce high density polyethylene, isotactic polypropylene (PP) or ethylene–propylene (EP)-copolymers including the EP-elastomers. The heterophasic phenomena and in particular the toughening of PP with amorphous ethylene–propylene copolymers have been studied. By terpolymerization of propylene, ethylene and other monomer such as 1-butene, terpolymers with very interesting performance are produced, thanks to the addition of 1-butene to ethylene–propylene copolymers. A decrease in Tgδ takes place in raw polymers, while polyethylene crystallinity is found at higher ethylene content than is the corresponding ethylene–propylene copolymers. An increase in tensile strength and a decrease in permanent deformation is noticed, both at environment and low temperature for the vulcanized products compared to the traditional ethylene–propylene copolymers. By the use of the above catalysts, copolymers and saturated terpolymers free from low volatile substance may be produced. Production of these new copolymers and saturated terpolymers can be carried out by highly simplified processes, mainly consisting of a polymerization and a monomer flashing step only, and the well known advantages have already been achieved with the new processes for the production of poly(α-olefin)s.