Effect of Shear Rate on the Orientation and Relaxation of a Vanillic Acid Based Liquid Crystalline Polymer
| Autor: | Carolus H. R. M. Wilsens, Eric Stellamanns, Sanjay Rastogi, Gijs W. de Kort, Nils Leoné, Dietmar Auhl |
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| Přispěvatelé: | AMIBM, RS: FSE Biobased Materials, Biobased Materials, RS: FSE AMIBM, Sciences, RS: FSE Sciences |
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Diffraction
Materials science Polymers and Plastics FLOW thermotropic polyester 02 engineering and technology TRANSIENT 010402 general chemistry RHEOLOGICAL BEHAVIOR 01 natural sciences Article orientation Physics::Fluid Dynamics lcsh:QD241-441 THERMOTROPIC POLYESTERS POLYETHYLENE TEREPHTHALATE relaxation lcsh:Organic chemistry Liquid crystal Shear stress ddc:530 MOLECULAR-ORIENTATION Anisotropy Coalescence (physics) Condensed matter physics PARA-OXYBENZOATE LYOTROPIC SOLUTIONS General Chemistry 021001 nanoscience & nanotechnology 0104 chemical sciences Shear rate domain texture Shear (geology) ddc:540 VECTRA B950 nematic melt 0210 nano-technology Material properties |
| Zdroj: | Polymers 10(9), 935 (2018). doi:10.3390/polym10090935 special issue: "Liquid Crystalline Polymers" Polymers, Vol 10, Iss 9, p 935 (2018) Polymers Volume 10 Issue 9 Polymers, 10(9):935. Multidisciplinary Digital Publishing Institute (MDPI) |
| ISSN: | 2073-4360 |
| DOI: | 10.3390/polym10090935 |
| Popis: | Polymers 10(9), 935 (2018). doi:10.3390/polym10090935 special issue: "Liquid Crystalline Polymers" In this study, we report on the visco-elastic response during start-up and cessation ofshear of a novel bio-based liquid crystal polymer. The ensuing morphological changes are analyzedat different length scales by in-situ polarized optical microscopy and wide-angle X-ray diffraction.Upon inception of shear, the polydomain texture is initially stretched, at larger strain break upprocesses become increasingly important, and eventually a steady state texture is obtained. The shearstress response showed good coherence between optical and rheo-X-ray data. The evolution of theorientation parameter coincides with the evolution of the texture: the order parameter increases as thetexture stretches, drops slightly in the break up regime, and reaches a constant value in the plateauregime. The relaxation of the shear stress and the polydomain texture showed two distinct processeswith different timescales: The first is fast contraction of the stretched domain texture; the second is theslow coalescence of the polydomain texture. The timescale of the orientation parameter’s relaxationmatched with that of the slow coalescence process. All processes were found to scale with shear ratein the tested regime. These observations can have far reaching implications for the processing ofliquid crystal polymers as they indicate that increased shear rates during processing can correspondto an increased relaxation rate of the orientation parameter and, therefore, a decrease in anisotropyand material properties after cooling. Published by MDPI, Basel |
| Databáze: | OpenAIRE |
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