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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:31 |
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Conference: Bucharest University Faculty of Physics 2004 Meeting
Section: Polymer Physics
Title:
The study of the polymers orientation in thermo-centrifugal fields
Authors:
S.Vulpe, Anca Dumitru, Adina Morozan, Livia Maria Constantinescu and Ioan Stamatin
Affiliation:
University of Bucharest, Faculty of Physics, Bucharest-Magurele, PO-BOX MG-11, 77125
E-mail
vulpesilviu@yahoo.com
Keywords:
carbon ribbons, anisotropy, molecular orientation
Abstract:
A large area of application requires advanced materials with oriented proprieties namely few: space-craft applications, catalyst support or membranes in fuel cell, heat sink spreader, electronic packaging, and anticorrosion coating.
The mecano-thermal properties are strongly dependent of the initial precursor, mainly of tacticity. Regular, highly oriented polymers films claim a syndiotactic precursor, practically impossible to be reached. To improve the performances of this materials was developed a new technique: the deposition of the thin films in high centrifuge field with simultaneous thermal treatment up to 300 C. This technique offers the possibility to obtain polymeric films with high degree of orientation. By thermal treatment up 900 C in argon atmosphere these polymers rise to carbon ribbons built up by well-aligned micro and nanocarbon fibers.
Simultaneous application of centrifuge field and thermal treatment induces transformations in preferential direction. The aim of this contribution is to present the results with polymers ribbons (polyacrylonitrile (PAN), polyethylene (PE), Novolac (resin), polyvinyl alcohol (APV)) deposited onto Al-foil or as freestanding carbon films in different stages of carbonization. The carbon ribbons of 1-100 microns, characterized by XRD, have a strongly anisotropy. The dependence of molecular orientation (monitored by FT-IR and scanning electron microscope (SEM)) in initial precursors and ribbons properties are taken in account.
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