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Comparative investigation on crystallization conditions dependence of polymorphs composition for β‐nucleated propylene/ethylene copolymer and propylene homopolymer
Author(s) -
Xiao Wenchang,
Feng Jiachun
Publication year - 2010
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.32229
Subject(s) - comonomer , crystallization , nucleation , differential scanning calorimetry , copolymer , materials science , polymer chemistry , isothermal process , chemical engineering , crystallinity , ethylene , thermodynamics , composite material , chemistry , organic chemistry , polymer , catalysis , physics , engineering
The crystallization conditions dependence of polymorphs composition in β nucleated propylene/ethylene copolymers (PPR) and propylene homopolymers (PPH) were comparatively investigated via wide angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC) measurements. It is interesting to note that the amount of β form as a function of crystallization conditions presents an opposite trend for the β nucleated PPR and the β nucleated PPH under the conditions we investigated. For the β nucleated copolymers, the content of β form shows also an opposite tendency with that of γ form with the change of crystallization conditions. The formation of γ form is preferred under lower cooling rates or higher isothermal crystallization temperatures, whereas the amount of β form increased with increasing the cooling rates or decreasing the isothermal temperatures. This opposite tendency could be interpreted in terms of the competition between the β nucleation ability of β nucleating agent and the γ nucleation action of the comonomer defects. The existing comonomer defects that favor the formation of γ form may suppress the nucleation ability of β nucleating agent. A higher proportion of β form in PPR containing a β nucleating agent could be achieved under faster cooling rates or lower crystallization temperatures. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010