A New Simulation Method of Interaction Between a Liquid Crystalline Polymer and Two Serrated Walls

This paper presents a new molecular model to define the interactions of a liquid crystalline polymer (LCP) flowing between two serrated walls. The wall is modeled by a rough atomic serrated wall. The roughness characteristics are given by the space and height of the serrated wall. Molecular model of the liquid crystalline polymer is described by an improved model that consists of GB (Gay-Berne) sites as rigid segments and LJ (Lennard-Jones) sites. There are two nonlinear springs each connecting from a GB site to a LJ site that situate between two GB sites as flexible segments. This improved model is newly developed to reduce the computational cost from that of the hybrid GB/LJ model, which has provided an effective way to investigate the boundary problems and flowing behaviors of LCPs at nano-scale. The molecular dynamics (MD) simulation using this reduced computational cost method to study the effect of boundary conditions on alignment and rheological properties of the LCP is shown in the result.

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The Effect of Surface Features on Nanorheology of LCP Melts in Nanochannels by MD Simulation

Journal of Tribology ◽

10.1115/1.2401219 ◽

2006 ◽

Vol 129 (1) ◽

pp. 171-176 ◽

Cited By ~ 2

Author(s):

Lan He ◽

Kai Leung Yung ◽

Yan Xu ◽

Yun Wen Shen

Keyword(s):

Rheological Properties ◽

Liquid Crystalline ◽

Md Simulation ◽

Molecular Model ◽

Crystalline Polymer ◽

Md Simulations ◽

Wall Surface ◽

New Model ◽

Surface Features ◽

Effect Of Surface

The effects of wall surface features on the rheological properties and phase orientation of liquid crystalline polymer (LCP) melts flowing in a nanochannel have been first investigated by molecular dynamics (MD) simulations. The surfaces are modeled as rough atomic serrated walls whereby the roughness is characterized by the period and amplitude of serration. The molecular chains of LCPs are depicted by a newly developed molecular model named the GB-spring-bead model. Through simulating the phase formation of LCP melts, the new model was evaluated and the results have shown the new model is efficient and accurate to describe semi-flexible main-chain LCP molecules. MD simulations of the effect of wall surface features on the LCP shear flow were conducted and the results have revealed the surface features affect greatly the rheological properties and phase orientations of LCP melts in a nanochannel (the distance between the upper wall and the lower wall is 12.8nm). Findings in this study provide very useful information in the injection molding of plastic products with nanofeatures.

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Observing the relaxation of molecular orientation in sheared liquid crystalline polymer solutions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178598 ◽

1990 ◽

Vol 48 (4) ◽

pp. 1092-1093

Author(s):

Wendy Putnam ◽

Christopher Viney

Keyword(s):

Molecular Orientation ◽

Liquid Crystalline Polymer ◽

Liquid Crystalline ◽

Crystalline Polymer ◽

Polymer Processing ◽

Molecular Alignment ◽

Global Alignment ◽

Shear Direction ◽

Axial Strength ◽

Strength And Stiffness

Liquid crystalline polymers (solutions or melts) can be spun into fibers and films that have a higher axial strength and stiffness than conventionally processed polymers. These superior properties are due to the spontaneous molecular extension and alignment that is characteristic of liquid crystalline phases. Much of the effort in processing conventional polymers goes into extending and aligning the chains, while, in liquid crystalline polymer processing, the primary microstructural rearrangement involves converting local molecular alignment into global molecular alignment. Unfortunately, the global alignment introduced by processing relaxes quickly upon cessation of shear, and the molecular orientation develops a periodic misalignment relative to the shear direction. The axial strength and stiffness are reduced by this relaxation.Clearly there is a need to solidify the liquid crystalline state (i.e. remove heat or solvent) before significant relaxation occurs. Several researchers have observed this relaxation, mainly in solutions of hydroxypropyl cellulose (HPC) because they are lyotropic under ambient conditions.

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Characterization of Thermotropic Liquid Crystalline Polymer Blends by Positron Annihilation Lifetime Spectroscopy

10.21236/ada253616 ◽

1992 ◽

Author(s):

Robert A. Naslund ◽

Phillip L. Jones

Keyword(s):

Polymer Blends ◽

Positron Annihilation ◽

Liquid Crystalline Polymer ◽

Liquid Crystalline ◽

Crystalline Polymer ◽

Positron Annihilation Lifetime Spectroscopy ◽

Positron Annihilation Lifetime ◽

Thermotropic Liquid Crystalline Polymer

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Phase Separation in Liquid-Crystalline Copolymer/Poly(methyl methacrylate) Blends

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19951869 ◽

1995 ◽

Vol 60 (11) ◽

pp. 1869-1874 ◽

Cited By ~ 1

Author(s):

Anatoly E. Nesterov ◽

Yuri S. Lipatov ◽

Vitaly V. Horichko

Keyword(s):

Phase Separation ◽

Methyl Methacrylate ◽

Liquid Crystalline Polymer ◽

Liquid Crystalline ◽

Ethylene Terephthalate ◽

Crystalline Polymer ◽

Scattering Method ◽

Thermally Induced ◽

Poly Methyl Methacrylate ◽

Copolymer Poly

The phase separation in the blends of poly(methyl methacrylate) and liquid-crystalline polymer (copolymer of ethylene terephthalate and p-hydroxybenzoic acid) has been studied by the light scattering method and the cloud point curves have been obtained. Simultaneously some morphological features of the blends have been observed. It was found that the initial blends are in the state of forced compatibility and that thermally induced phase separation occurs by the mechanism of spinodal decomposition but presumably in the non-linear regime.

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Protein detection using aqueous/LC interfaces decorated with a novel poly(N-isopropyl acrylamide) block liquid crystalline polymer

RSC Advances ◽

10.1039/c3ra42472c ◽

2013 ◽

Vol 3 (39) ◽

pp. 17930 ◽

Cited By ~ 1

Author(s):

Yong-Dae Jung ◽

Soo-Young Park

Keyword(s):

Liquid Crystalline Polymer ◽

Liquid Crystalline ◽

Protein Detection ◽

Crystalline Polymer ◽

Isopropyl Acrylamide

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Fiber Formation and Structural Development of HBA/HNA Thermotropic Liquid Crystalline Polymer in High-Speed Melt Spinning

Polymers ◽

10.3390/polym13071134 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1134

Author(s):

Bo Seok Song ◽

Jun Young Lee ◽

Sun Hwa Jang ◽

Wan-Gyu Hahm

Keyword(s):

Mechanical Properties ◽

Shear Rate ◽

High Speed ◽

Melt Spinning ◽

Liquid Crystalline Polymer ◽

Liquid Crystalline ◽

Crystalline Polymer ◽

Fiber Formation ◽

Structural Development ◽

Thermotropic Liquid Crystalline Polymer

High-speed melt spinning of thermotropic liquid crystalline polymer (TLCP) resin composed of 4-hydroxybenzoic acid (HBA) and 2-hydroxy-6-napthoic acid (HNA) monomers in a molar ratio of 73/27 was conducted to investigate the characteristic structure development of the fibers under industrial spinning conditions, and the obtained as-spun TLCP fibers were analyzed in detail. The tensile strength and modulus of the fibers increased with shear rate in nozzle hole, draft in spin-line and spinning temperature and exhibited the high values of approximately 1.1 and 63 GPa, respectively, comparable to those of industrial as-spun TLCP fibers, at a shear rate of 70,000 s−1 and a draft of 25. X-ray diffraction demonstrated that the mechanical properties of the fibers increased with the crystalline orientation factor (fc) and the fractions of highly oriented crystalline and non-crystalline anisotropic phases. The results of structure analysis indicated that a characteristic skin–core structure developed at high drafts (i.e., spinning velocity) and low spinning temperatures, which contributed to weakening the mechanical properties of the TLCP fibers. It is supposed that this heterogeneous structure in the cross-section of the fibers was induced by differences in the cooling rates of the skin and core of the fiber in the spin-line.

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