We report the design, synthesis, morphology, phase behavior, and mechanical properties of semicrystalline, polyolefin-based block copolymers. By using living, stereoselective insertion polymerization catalysts, syndiotactic polypropylene-block-poly(ethylene-co-propylene)-block-syndiotactic polypropylene and isotactic polypropylene-block-regioirregular polypropylene-block-isotactic polypropylene...

Propene-hexene copolymers crystallize in a new polymorphic form of isotactic polypropylene when the concentration of hexene is higher than nearly 10-15 mol %. The hexene units are included in the crystals, inducing an increase of density that allows crystallization of 3-fold helical chains in a trigonal unit cell according to the space group R3c or Rc, where the helical symmetry of the chains i...

Bulk isotactic polypropylene in the a form was studied using density functional theory-based computations. The computed physical structure of this system is in excellent agreement with available experimental data. The electronic band structure, ionization potential, and electron affinity were also determined. The impact of various types of chemical imperfections (including double bond, hydroxyl...

Since the maximum foaming temperature window is only about 4 °C for supercritical CO₂ (scCO₂) foaming of pristine polypropylene, it is important to raise the melt strength of polypropylene in order to more easily achieve scCO₂ foaming. In this work, radiation cross-linked isotactic polypropylene, assisted by the addition of a polyfunctional monomer (triallylisocyanurate, TAIC), was employed in ...

BOITOUT, Hugo, "Influence of the temperature on flow-induced crystallization of isotactic polypropylene and propylene-ethylene random copolymer" (2014). Influence of the temperature on flow-induced crystallization of isotactic polypropylene and propylene-ethylene random copolymer Influence of the temperature on flow-induced crystallization of isotactic polypropylene and propylene-ethylene rando...

Nanocomposites of isotactic polypropylene (iPP) and date wood fiber were prepared after modification of the host matrix by reactive extrusion grafting of maleic anhydride. Chemical and mechanical treatment of date wood flour (WF) was conducted to obtain nanocrystalline cellulose. Layered silicates (clay) were partially intercalated with date wood fiber, and the modified layered silicate was use...

in this study we have tested the ability of a standard dft computational protocol to reproduce the experimentally obtained stereoselectivity of 26 different c2-symmetric zirconocene catalysts active in propylene polymerization. the catalysts were chosen for their relevance in metallocene catalyzed polymerization of propylene. to this end, primary insertion of both si- and re-propylene enantiofa...

VistamaxxTM Specialty Elastomers are polyolefin elastomers with isotactic propylene crystallinity. These polymers contain a predominant (>80%) amount of propylene with isotactic propylene crystallinity, with the balance of the composition being ethylene and other αolefins. This new family of thermoplastic elastomers are highly elastic and exhibit excellent recovery from deformation. These polym...

A filament stretching extensional rheometer with a custom-built oven was used to investigate the effect of uniaxial flow on the crystallization of polypropylene. Prior to stretching, samples were heated to a temperature well above the melt temperature to erase their thermal and mechanical histories and the Janeschitz-Kriegl protocol was applied. The samples were stretched at extension rates in ...