To evaluate the microstructure-property correlation of thermotropic liquid crystalline polymer blends and composites
The synthesis and modification of thermotropic liquid crystalline polymers (TLCP) for different final applications are currently hot topics of industrial as well as academic research. The copolymerization of different comonomers leads to polymers with different liquid crystalline characteristics, melting temperatures, rheological behavior. The incorporation of some comonomers is applied to reduce the processing temperature but still keep the liquid crystalline characteristics. TLCPs having different chemical structure are processed to different end-use forms of products by injection molding, extrusion, stretching, blowing and spinning. TLCPs are currently produced by Solvay, Eastman, Ticona, Polyplastics, DuPont, Mitsubishi, Sumitomo, and Unitika, and are commercialized as glass fiber-filled, glass beads-filled, glass flakes-filled, silica-filled grades for injection-molded parts, and tubes, films, bottles and fibers in IT, automobile, chemical, medical and hi-tech industries. The microstructure of commercialized TLCP blends and composites is closely related to their processing conditions. The relation between the rheological properties and the resultant microstructure of these blends and composites should be well established. The aim of this research is to evaluate microstructure-property relation of the commercialized TLCP blends and composites (e.g. glass fiber-filled grades) by the rheological measurement (dynamic and steady rheology), morphology observation (SEM, WAXD) and property evaluation (mechanical tests).
Previous IUPAC project resulted in one paper is published in Pure and Applied Chemistry, 76(11), 2027-2049 (2004), “Rheological properties and associated structural characteristics of some aromatic polycondensates including liquid-crystalline polyesters and cellulose derivatives“, J. L. White, L. Dong, P. Han and H.M. Laun. This paper reports 4 different types of liquid crystalline polyesters and 1 type of glass fiber-filled LCP.
In recent years, the rapid development of IT products leads to an annual consumption growth of 25% for commercialized LCP blends and composites. Different commercialized grades of LCP blends and composites (with different fillers) are available for fabrication of final products. It is of interest to have a new IUPAC project to correlate the microstructure and rheological properties of filled LCP blends and composites.
The study of this project will be focused on TLCP pellets as follows:
- Ticona & Polyplastics VectraÂ® A, a commercial aromatic copolyester comprising of 73 mol% hydroxybenzoic acid and 27 mol% hydroxynaphthoic acid;
- Ticona & Polyplastics VectraÂ® B, a commercial aromatic copolyester comprising of 60% 2,6-hydroxynaphthanoate, hydroxy naphthoic acid, 20% terephthalic acid and 20%aminophenol;
- Unitika RodrunÂ® LC3000, a commercial aromatic copolyester comprising of 60% p-hydroxybenzoate, hydroxybenzoic acid and 40% poly(ethylene terephthalate);
- Unitika RodrunÂ® LC5000, a commercial aromatic copolyester comprising of 80% p-hydroxybenzoate, hydroxybenzoic acid and 20% poly(ethylene terephthalate);
The techniques used are itemized as follows:
- Rheological Properties [S. H. Kim, J. He]
(a) Dynamic Viscoelasticity
(b) Stress Relaxation
(c) Shear/Elongational Viscosities
- Morphology characterization [S. C. Kim]
- Blending with other polymers [J. He]
(a) Rheological properties
(b) Morphology observation
- Crystallization [S. H. Kim, J. He]
- Mechanical testing [S. H. Kim, J. He]
(a) Static mechanical properties
(b) Dynamic mechanical analysis
March 2006 – project announcement published inÂ Chem. Int. Mar-Apr 2006, p. 28
Jan 2011 -Â Manuscripts are under reviewi. The
project is planned to be completed at the end of 2011.
Dec 2011 – project completed – the following outcome is published: Mi, Q., Zhang, X. and He, J. (2011), Rheological hybrid effect in dually filled polycarbonate melt containing liquid crystalline polymer. Polymer Engineering & Science. doi: 10.1002/pen.22082 (first published online: 25 JUL 2011)