Novel polypropylene materials

Recent progress in transition metal catalyzed propylene polymerization base d upon single-site catalysts and melt compounding of polypropylene is stimu lating the development of novel polypropylene materials with unconventional property combinations such as improved low temperature toughness, low haze , elasticity, and improved toughness/stiffness balance. As a function of me tallocene architectures, polypropylene microstructures can be varied over a very wide range in order to produce thermoplastic elastomers and highly fl exible polymers as well as stiff engineering thermoplastics and fibers. Con trol of polypropylene molecular architectures, especially random placement of steric irregularities in the polypropylene main chain, and the addition of clarifiers represents the key to producing novel transparent polypropyle nes. Metallocene-based ethene/1-olefn copolymers such as poly(ethylene-co-1 -butene) are attractive blend components to afford either single-phase flex ible or two-phase rigid blends with improved low temperature impact strengt h as a function of the 1-butene content. New families of polypropylene nano composites, containing nanowhiskers and anisotropic nanoparticles derived f rom organophilic layered silicates, exhibit effective matrix reinforcement at low filler content.