Abstract
The effect of low steady shear rates on the phase diagram and phase-separated morphology of liquid crystalline polymer (LCP)/polycarbonate (PC) blends was studied. Experiments were carried out with polarized light microscopy in conjunction with a shear stage for directly monitoring the phase separation behavior of the blends. Phase separation temperatures under shear flow were lower than those observed under quiescent conditions. Consequently, the phase diagram of the blend was shifted to a lower position, relative to the phase diagram obtained under quiescent conditions. The temporal morphological development of phase separation in the blends was also affected by the shear. Phase-separated structures were monitored, with and without shear, in blends containing 50 wt.% LCP. Results showed that the speed and amount of phase separation increased when shear was applied. The results indicate that these blends undergo shear-enhanced phase separation at low steady shear rates.
References
Acierno, D., La Mantia, F. P.: Processing and Properties of Liquid Crystalline Polymers and LCP Based Blends, ChemTec, Toronto(1993).Search in Google Scholar
Brostow, W.: Mechanical and Thermophysical Properties of Polymer Liquid Crystals, Chapman & Hall, London(1998).10.1007/978-1-4615-5799-9Search in Google Scholar
Cohen-Addad, S., et al., Liquid Crystalline Polyester and Polysulphone Mixtures: Observation of Phase Separation and Aggregation, Polymer, 32, 2319–2324(1991).10.1016/0032-3861(91)90067-SSearch in Google Scholar
Endoh, M. K., et al., Shear-Induced Structures in Semidilute Polystyrene Solution: Effect of Solvent Quality, Macromolecules, 35, 7692–7699(2002).10.1021/ma0203389Search in Google Scholar
Endoh, M. K., et al., Effects of Shear Flow on a Semidilute Polymer Solution under Phase-Separating Condition, Polymer, 47, 7271–7281(2006).10.1016/j.polymer.2006.05.075Search in Google Scholar
Fernandez, M. L., et al., Complex Miscibility Behavior for Polymer Blends in Flow, Polymer, 36, 149–154(1995).10.1016/0032-3861(95)90686-VSearch in Google Scholar
Katsaros, J. D., et al., The Effects of Flow on Miscibility in a Blend of Polystyrene and Poly(Vinyl Methyl Ether), Polym. Eng. Sci., 29, 1434–1445(1989).10.1002/pen.760292005Search in Google Scholar
Kyu, T., Zhuang, P., Phase Segregation in Thermotropic Liquid Crystalline Copolyester and Polycarbonate Blends, Polym. Commun., 29, 99–102(1988).10.1016/0032-3861(88)90206-6Search in Google Scholar
Lee, K.-W. D., et al., Determination of the Phase Diagram of HBA-HNA Liquid Crystalline Polymer/Polycarbonate Blends, J. Appl. Polym. Sci., 111, 396–407(2009).10.1002/app.29103Search in Google Scholar
Nagaya, T., et al., Observation of Phase Separation Process in the Binary Mixture of Nematic and Isotropic Polymers, J. Phys. Soc. Jpn., 58, 3600–3605(1989).10.1143/JPSJ.58.3600Search in Google Scholar
Rasband, W. S., ImageJ (version 1.38n), U.S. National Institutes of Health, Bethesda, Maryland, USA(2007)http://rsb.info.nih.gov/ij/.Search in Google Scholar
Saito, S., et al., Structures of a Semidilute Polymer Solution under Oscillatory Shear Flow, Macromolecules, 32, 4879–4888(1999).10.1021/ma990031iSearch in Google Scholar
Sperling, L. H., Introduction to Physical Polymer Science, 4th Edition, Wiley-Interscience, Hoboken(2006).Search in Google Scholar
© 2009, Carl Hanser Verlag, Munich
