Title: Studies on blends of a thermotropic liquid crystalline polymer with some thermoplastics

Authors: Markku T. Heino, Jukka V. Seppala

Addresses: Helsinki University of Technology, Department of Chemical Engineering, Kemistintie 1, SF-02150 Espoo, Finland. ' Helsinki University of Technology, Department of Chemical Engineering, Kemistintie 1, SF-02150 Espoo, Finland

Abstract: A totally aromatic thermotropic liquid crystalline polymer was melt blended in a twin-screw-extruder mainly with polyethylene terephtalate and polypropylene, and the blends were injection moulded into the form of standard test specimens. Mechanical properties of the blends were studied by tensile and impact tests and the blend morphology by scanning electron microscopy. Thermal expansion coefficients and heat deflection temperatures were also determined. The blends were two-phase systems, where LCP was as small spheres or fibres in the matrix. Skin-core morphology was found. LCP improved the mechanical properties as well as thermal and dimensional stability of the thermoplastics studied. Generally, the tensile strength, elastic modulus and HDT of the matrices increased with increasing LCP content, while elongation at break and Charpy impact strength decreased. This means that the blends were stiffer but also more brittle than the matrix polymers.

Keywords: melt blending; thermotropic polymers; aromatic polymers; liquid crystalline polymers; LCP; thermoplastics; injection moulding; mechanical properties; thermal properties; morphology; twin-screw extruders; thermal expansion coefficient; heat deflection temperature; tensile strength; elastic modulus; stiffness; brittleness.

DOI: 10.1504/IJMPT.1992.036499

International Journal of Materials and Product Technology, 1992 Vol.7 No.1, pp.56 - 64

Published online: 04 Nov 2010 *

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