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Nonisothermal melt‐crystallization kinetics of isotactic polypropylene synthesized with a metallocene catalyst and compounded with different quantities of an α nucleator
Author(s) -
Dobreva T.,
LópezMajada J. M.,
Pereña J. M.,
Pérez E.,
Benavente R.
Publication year - 2008
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.28105
Subject(s) - crystallization , tacticity , materials science , crystallinity , differential scanning calorimetry , activation energy , nucleation , polymer chemistry , kinetics , surface energy , metallocene , chemical engineering , avrami equation , post metallocene catalyst , copolymer , crystallography , thermodynamics , chemistry , composite material , polymerization , organic chemistry , polymer , crystallization of polymers , quantum mechanics , physics , engineering
Abstract The nonisothermal crystallization kinetics of a metallocene‐made isotactic polypropylene (m‐iPP) and its compounds with 0.1 wt % and 0.3 wt % of a sorbitol derivative [1,3:2,4‐bis(3,4‐dimethylbenzylidene)sorbitol (DMDBS); an α nucleator] were investigated by differential scanning calorimetry at different cooling rates from the melt. The nucleation efficiency was proved by a significant increase in the crystallization temperatures (accompanied by a slight augmentation of the degree of crystallinity and a decrease in the crystal sizes). This increase in the crystallization temperatures led to higher amounts of fractional content in the γ polymorph, even though DMDBS was supposed to be a nucleator for the α form. The Avrami and Ozawa methods effectively described only the early stage of crystallization, whereas a combined Avrami–Ozawa method was valid for the whole crystallization process. The values of the exponent for this method decreased for nucleated samples in the later stage of crystallization, especially in the case of m‐iPP with 0.3 wt % DMDBS added (m‐iPP03). The activation energy of the process and the surface free energy were also estimated. The production of considerable proportions of the γ polymorph in m‐iPP03 corresponded to higher values of the activation energy and lower values of the surface free energy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008