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How does a polymerized compounding affect the nucleation effect of a sorbitol derivative nucleating agent in isotactic polypropylene melt crystallization?
Author(s) -
Yi QingFeng,
Wen XiaoJing,
Niu Hui,
Dong JinYong
Publication year - 2012
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.37824
Subject(s) - materials science , nucleation , tacticity , differential scanning calorimetry , crystallization , polymerization , chemical engineering , polymer , polymer chemistry , compounding , sorbitol , polypropylene , dispersion (optics) , composite material , organic chemistry , chemistry , thermodynamics , physics , engineering , optics
Abstract In this article, we investigate the effect of a new polymerized compounding method on the nucleation behavior of a sorbitol derivative nucleating agent for isotactic polypropylene (iPP). This method uses a sorbitol derivative nucleating agent, for example, 1,3: 2,4‐dimethylbenzylidene sorbitol (DMBS), which displays itself as aggregated fibrillar crystals, as a support for C 2 ‐symmetric ansa ‐metallocenes best represented by rac ‐Me 2 Si[2‐Me‐4‐Naph‐Ind] 2 ZrCl 2 . Activating this DMBS‐supported metallocene catalyst with methylaluminoxane, a following in situ propylene polymerization results in the formation of iPP/DMBS composition polymers having controllable DMBS concentrations (by virtue of polymerization productivity control), with the DMBS dispersion driven by catalyst fragmentation. Three iPP/DMBS composition polymers having DMBS concentrations of 0.22, 031, and 0.52 wt % were prepared by this means, which, along with their analog melt‐mixed counterparts, were subjected to melt crystallization kinetics and crystal morphology studies using differential scanning calorimetry, polarized optical microscopy, and UV–vis spectroscopy. With systematically higher nucleation efficiencies and lower crystallization activation energies, the polymerized iPP/DMBS composition polymers exhibited generally stronger DMBS nucleation effects when compared with their melt‐mixed counterparts. Such a benefit was accounted for by a more homogeneous dispersion and better wettability by iPP matrix of DMBS that led to the formation of more nucleation sites and faster crystallization. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013