Characterization of the Skin Orientation of Thermotropic Liquid-Crystalline Copolyester Moldings with Near-Edge X-ray Absorption Fine Structure

Published

May 11, 2006

Author(s)

Robert A. Bubeck, L S. Thomas, S Rendon, W R. Burghardt, A Hexemer, Daniel A. Fischer

Abstract

The process of injection molding net-shape parts from thermotropic liquid crystalline polymers (TLCPs) results in a skin-core macrostructure. The underlying orientation in the core and the skin may differ both in magnitude and direction. A combination of near edge X-ray absorption fine structure (NEXAFS) spectroscopy and two dimensional wide-angle X-ray scattering (2-D WAXS) in transmission was used to characterize the orientation in injection molded plaques fabricated from thermotropic liquid crystalline copolyesters based upon either 4,4'-dihydroxy- - methylstilbene (DH MS) or 6-hydroxy-2-naphthoic acid/6-hydroxybenzoic acid (HBA/HNA). NEXAFS is presented as a non-invasive in situ means of determining surface layer orientation that samples to a depth of as little as 2 nm and does not require slicing or ultramicrotoming of the samples. The effects of various processing conditions on surface orientation in the region of the centerline of square injection molded plaques are presented and discussed. Comparisons were made between orientation parameters obtained by 2-D wide-angle X-ray scattering (2-D) WAXS) in transmission, which is dominated by the microstructure in the core, and the NEXAFS technique.

Citation

Journal of Applied Polymer Science

Volume

98

Pub Type

Journals

Keywords

crystalline polymer, injection molded, surface orientation, thermotropic liquid

Citation

Bubeck, R. , Thomas, L. , Rendon, S. , Burghardt, W. , Hexemer, A. and Fischer, D. (2006), Characterization of the Skin Orientation of Thermotropic Liquid-Crystalline Copolyester Moldings with Near-Edge X-ray Absorption Fine Structure, Journal of Applied Polymer Science (Accessed October 10, 2025)