Structure and Properties of New Polyolefin Thermoplastic Elastomers

Thermoplastic elastomers (TPE) are attractive materials because they combine the processing advantages and recycling potential of thermoplastics with the flexibility and low modulus of elastomers. This paper reports the synthesis and characterization of polyolefin TPE from ?-olefin chain-walking polymerization. The polymers were characterized by 13C NMR for quantification of the total branching level and branch-type distribution. The numerous combinations of monomer insertions and chain-walking paths afford polymers with unique microstructure and properties, depending on the monomer length. The thermal properties and crystallinity of the polymers are strongly controlled by their microstructure: the presence of long branches interferes on the crystallization and melting behavior. A comprehensive investigation of the mechanical behaviour of the polymers by means of uniaxial stretching until failure, step-cycle and creep tensile tests was carried out. Overall, the polymers exhibit a broad spectrum of tensile properties, depending on their microstructure and crystallinity. 1-Octene and 1-decene polymers behave as elastomers with excellent mechanical properties, i.e., high elongation at break (up to 1500%) and good strain recovery, while the 1-octadecene polymer behaves as plastomers.