Open AccessCrystallization of the mesomorphic form and control of the molecular structure for tailoring the mechanical properties of isotactic polypropylene
Author(s) -
Rosa Claudio,
Auriemma Finizia,
Girolamo Rocco,
Ballesteros Odda Ruiz
Publication year - 2014
Publication title -
journal of polymer science part b: polymer physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.65
H-Index - 145
eISSN - 1099-0488
pISSN - 0887-6266
DOI - 10.1002/polb.23473
Subject(s) - mesophase , tacticity , materials science , crystallization , crystallinity , thermoplastic elastomer , composite material , polypropylene , ductility (earth science) , elastomer , chemical engineering , polymer chemistry , polymerization , polymer , copolymer , liquid crystal , creep , optoelectronics , engineering
ABSTRACT The combination of the control of the concentration of stereodefects in isotactic polypropylene using metallocene catalysts and the crystallization via the mesophase is a strategy to tailor the mechanical properties. Stiff materials, flexible materials, and thermoplastic elastomers can be produced depending only on the concentration of rr stereodefects. Modulus, ductility, and strength can be modulated through the crystallization of α and γ forms or of the mesophase. Different morphologies are observed depending on the stereoregularity and conditions of crystallization. Crystals of the mesomorphic form always exhibit a nodular morphology, accounting for the similar good deformability of all quenched samples, whatever the concentration of stereodefects. The mesophase transforms by thermal treatments into the α form preserving the nodular morphology, with increase of strength while maintaining the ductility typical of the mesophase. Annealing of the mesophase permits a precise adjustment of crystallinity and size of nodular crystals offering additional options to modify the mechanical properties. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52 , 677–699