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Thermooxidation effects on the structuring of molten polypropylene–clay nanocomposites
Author(s) -
Xu Yibin,
Yang Jianmao,
Xu Yuanze
Publication year - 2006
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.2031
Subject(s) - organoclay , polypropylene , materials science , nanocomposite , charring , composite material , rheology , polymer , thermogravimetric analysis , plateau (mathematics) , volatilisation , chemical engineering , chemistry , organic chemistry , mathematical analysis , mathematics , engineering
The storage modulus G ′ plateau at low frequency, the solid‐like state in molten nanocomposites, has been verified by comparative studies in air or nitrogen for polypropylene (PP)–organoclay with compatibilizer (PPCH). It was found that the thermal oxidation does not only degrade the polymer chain but also enhances the structuring in PPCH. Well‐designed rheology testing was able to distinguish the surface effect from the bulk responses. The inhomogeneity of clay distribution in samples was also studied using X‐ray element analysis. We found that the apparent G ′ plateau was mainly caused by diffusive oxidation starting from sample‐free surface in oxidative environment and, finally, a charring layer at the free surface was gradually developed, which is responsible for the solid state or very high apparent G ′ plateau. This structuring scheme agrees with the dehydrogenation mechanism of oxidation leading to crosslinking and volatilization of PP composites, while the participation of organoclay is essential. A silane coupling agent may retard this process by interacting with silicates. Copyright © 2006 Society of Chemical Industry