Free volume in PEP-silica nanocomposites with varying molecular weight

Autor:	Christian Ohrt, Franz Faupel, Gerald J. Schneider, Tönjes Koschine, Lutz Willner, Klaus Rätzke
Rok vydání:	2014
Předmět:	chemistry.chemical_classification Nanocomposite Materials science Polymers and Plastics Polymer nanocomposite Organic Chemistry Polymer Heat capacity Adsorption Chemical engineering chemistry Volume (thermodynamics) Polymer chemistry Materials Chemistry Spectroscopy Glass transition
Zdroj:	Polymer. 55:143-149
ISSN:	0032-3861
DOI:	10.1016/j.polymer.2013.11.021
Popis:	The influence of confinement in polymer-nanocomposites on free volume and glass transition of the polymer chains was studied. The molecular weight (Mw) of poly(ethylene-alt-propylene) (PEP) was varied from 3k to 200k and so the end-to end distance of the chains at fixed diameter (∼15 nm) and concentration (15%) of the silica nanoparticles increased. Thus the topological confinement increases with increasing Mw. Using hydrophobic PEP and particles functionalized with short organic molecules, we can rule out contributions of permanent adsorption of the chains. DSC showed no change in glass transition temperature. The decrease in the specific heat capacity could be explained by a simple mixing rule. By positron annihilation lifetime spectroscopy, taking properly into account contributions of the silica particles, we rule out an influence of the geometrical confinement on the free volume in the PEP nanocomposites studied here.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::fd41f532fc15a232dabf6bba95917965 https://doi.org/10.1016/j.polymer.2013.11.021 Zobrazit plný text záznamu Full Text from ScienceDirect