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Effect of composition and molecular weight on the crystallization behavior of blends of iPP and a metallocenic ethylene/1‐octene copolymer
Author(s) -
Prieto Óscar,
Pereña José M.,
Benavente Rosario,
Cerrada María L.,
Pérez Ernesto
Publication year - 2002
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(200208)203:12<1844::aid-macp1844>3.0.co;2-w
Subject(s) - crystallinity , materials science , differential scanning calorimetry , crystallization , copolymer , tacticity , ethylene , octene , polymer chemistry , annealing (glass) , polymer blend , chemical engineering , composite material , polymer , polymerization , chemistry , thermodynamics , organic chemistry , catalysis , engineering , physics
Blends covering the entire range of compositions of a metallocenic ethylene/1‐octene copolymer and two conventional isotactic poly(propylene)s (iPPs) of different molecular weight have been prepared, analyzing (by differential scanning calorimetry and X‐ray diffraction) the effect of composition and molecular weight on the crystallization behavior. It was found that those blends rich in the iPP component show a behavior practically coincident with the weighted addition of the two components. On the contrary, significant deviations were found for the blends where the ethylene copolymer is the major component. These deviations are considerably more important in the case of the blends with iPP of higher molecular weight. In such a case, the blend with a 25% by weight of iPP presents a normalized crystallinity degree of only 0.20, in comparison with the value of 0.57 exhibited by the pure iPP. After annealing at 120 °C for 10 minutes, and cooling back to room temperature, that blend increases its crystallinity degree up to only 0.40.Variation of peak melting, Tm, and crystallization, Tc, temperatures of both components with the composition in the blends of iPP1/CEO (open symbols) and iPP2/CEO (solid symbols).