Crystallization and melting of isotactic polypropylene crystallized from quiescent melt and stress‐induced localized melt

Temperature dependency of crystalline lamellar thickness during crystallization and subsequent melting in isotactic polypropylene crystallized from both quiescent molten state and stress‐induced localized melt was investigated using small angle X‐ray scattering technique. Both cases yield well‐defined crystallization lines where inverse lamellar thickness is linearly dependent on crystallization temperature with the stretching‐induced crystallization line shifted slightly to smaller thickness direction than the isothermal crystallization one indicating both crystallization processes being mediated a mesomorphic phase. However, crystallites obtained via different routes (quiescent melt or stress‐induced localized melt) show different melting behaviors. The one from isothermal crystallization melted directly without significant changing in lamellar thickness yielding well‐defined melting line whereas stress‐induced crystallites followed a recrystallization line. Such results can be associated with the different extent of stabilization of crystallites obtained through different crystallization routes. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 957–963     

Simulation of non-Newtonian ink transfer between two separating plates for gravure-offset printing

The inks used in gravure-offset printing are non-Newtonian fluids with higher viscosities and lower surface tensions compared to Newtonian fluids. This paper examines the transfer of a non-Newtonian ink between two parallel plates when the top plate is moved upward with a constant velocity while the bottom plate is held fixed. Numerical simulations were carried out using the Carreau model to explore the behavior of a non-Newtonian ink in gravure-offset printing. The volume of fluid (VOF) model was adopted to demonstrate the stretching and break-up behaviors of the ink. The results indicate that the ink transfer ratio is greatly influenced by the contact angle, especially the contact angle at the upper plate (α). For lower values of α, oscillatory or unstable behavior of the position of minimum thickness of the ink between the two parallel plates during the stretching period is observed. This oscillation gradually diminishes as the contact angle at the upper plate is increased. Moreover, the number of satellite droplets increases as the velocity of the upper plate is increased. The surface tension of the conductive ink shows a positive impact on the ink transfer ratio to the upper plate. Indeed, the velocity of the upper plate has a significant influence on the ink transfer in gravure-offset printing when the Capillary number (Ca) is greater than 1 and the surface tension dominates over the ink transfer process when Ca is less than 1.     

Amphipilic and mesogenic carbohydrates XII. New thermotropic mesogens based on perfluoroalkyl-substituted carbohydrates

In continuing studies of amphiphilic and mesogenic carbohydrates, the mesomorphic properties of a new group of perfluoroalkylated amphiphilic mesogens are discussed. Smectic A phases dominate the mesomorphic behaviour of the new materials, but one compound exhibits a columnar mesophase and three others have SmA-SmC* transitions. The synthesis of these materials has already been reported and involved dithionite-mediated O- and S-perfluoroalkylations with 1-iodoperfluoroalkanes.     

Polarization of Molecular ions in NaTCNQ and TTF. TCNQ Crtstals

Self-consistent electrostatic intersite potentials and atomic charges have been calculated. Lattice cohesion energy for NaTCNQ has been reproduced when polarization of TCNQ- anion in the lattice was taken into account.     

Ferroelectric compounds with chiral (S)-1-methylheptyloxycarbonyl terminal chain – their miscibility and a helical pitch

Compounds with the same chiral terminal chain but different structure of rigid core and non-chiral terminal chain were added to basic highly tilted ferroelectric compound in the aim of establishing whether the miscibility of phases, especially ferroelectric phase, exists in these compounds and what are the helical pitch and tilt angle temperature dependence in bicomponent systems. In certain systems, we obtained a mixture with very short helical pitch at broad temperature range of ferroelectric phase, which open opportunities for the formulation of multicomponent mixtures for fast switching ferroelectric liquid crystals modes.     

Aqueous solution behavior of comb‐shaped poly(2‐ethyl‐2‐oxazoline)

A series of comb polymers consisting of a methacrylate backbone and poly(2‐ethyl‐2‐oxazoline) (PEtOx) side chains was synthesized by a combination of cationic ring‐opening polymerization and reversible addition–fragmentation chain transfer polymerization. Small‐angle neutron scattering (SANS) studies revealed a transition from an ellipsoidal to a cylindrical conformation in D₂O around a backbone degree of polymerization of 30. Comb‐shaped PEtOx has lowered T_g values but a similar elution behavior in liquid chromatography under critical conditions in comparison to its linear analog was observed. The lower critical solution temperature behavior of the polymers was investigated by turbidimetry, dynamic light scattering, transmission electron microscopy, and SANS revealing decreasing T_cp in aqueous solution with increasing molar mass, the presence of very few aggregated structures below T_cp, a contraction of the macromolecules at temperatures 5 °C above T_cp but no severe conformational change of the cylindrical structure. In addition, the phase diagram including cloud point and coexistence curve was developed showing an LCST of 75 °C of the binary mixture poly[oligo(2‐ethyl‐2‐oxazoline)methacrylate]/water. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Viewing angle controllable fringe and in-plane switching vertical alignment LCD

A viewing angle controllable fringe and in-plane switching vertical alignment liquid crystal display (LCD) structure has been proposed. To realise the change from wide viewing angle (WVA) to narrow viewing angle (NVA) in a single LCD panel, the bias voltage is applied on the common electrode, and NVA can decreases with the increasing bias voltage. In WVA mode, the viewing angle cone (contrast ratio larger than 1000:1) is almost 70° and the contrast ratio is larger than 100:1 in arbitrary azimuthal directions. In NVA mode, the viewing angle cone (10:1) can continuously and uniformly change from 40° to 20°.     

Advanced wide viewing angle technology in liquid crystal display modes

This paper reviews the advanced optical configurations for in-plane switching (IPS) and vertical alignment (VA) liquid crystal (LC) cells with wide viewing angle in a visible wavelength range. Optical compensation and optimisation to eliminate off-axis light leakage in the dark state is performed on a Poincaré sphere using the trigonometric and the Muller matrix method. By optimising the wavelength dispersion of used optical retardation films, we could achieve wide-view characteristics for both the IPS and VA LC cells. In addition, we show the advanced wide-view technology for a reflective LC mode.     

微重坏境下旋转对称贮箱内静液面方程Runge-Kutta数值解

由力学平衡方程导出了旋转对称贮箱内静液面的二阶非线性常微分方程，接着具体了球腔，旋转 椭球腔、柱面腔的边界接触角条件，最后使用Ｒｕｎｇｅ－Ｋｕｔｔａ法在计算机上得出了数值结果，绘出静液面开头曲线，分析了算法特点。