• 제목/요약/키워드: Polymer science

Search Result 5,797, Processing Time 0.036 seconds

Temperature dependent electro-optical studies of liquid crystal in Fringe Field Switching (FFS), In-plane switching (IPS), and Patterned Vertical Alignment (PVA) modes

  • Jo, Eun-Mi;Srivastava, Anoop Kumar;Kim, Mi-Young;Kim, Sung-Min;Lee, Seung-Hee;Ji, Seung-Hoon;Lee, Gi-Dong
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2008.10a
    • /
    • pp.320-323
    • /
    • 2008
  • In this paper, electro-optical characteristic of Nematic Liquid crystal (LC) with varying temperature in different LCD modes, namely Fringe Field Switching (FFS), In-plane switching (IPS), and Patterned Vertical Alignment (PVA) modes are investigated and compared. Electro optic me asurements suggest that rate of change of transmission with temperature in FFS mode was lowest and much more thermally stable as compared to IPS and PVA m odes. However the electro-optical characteristic of patterned vertical alignment (PVA) mode was most affected by changing temperature. The measured threshold voltage was found to be much more thermally stable in FFS and IPS modes than that of PVA mode.

  • PDF

Temperature Dependence of the Electro-optic Characteristics in the Liquid Crystal Display Switching Modes

  • Jeon, Eun-Jeong;Srivastava, Anoop Kumar;Kim, Mi-Young;Jeong, Kwang-Un;Choi, Jeong-Min;Lee, Gi-Dong;Lee, Seung-Hee
    • Journal of Information Display
    • /
    • v.10 no.4
    • /
    • pp.175-179
    • /
    • 2009
  • As the physical properties of nematic liquid crystals vary with respect to temperature, the performances of liquid crystal displays (LCDs) are highly dependent on temperature. Additionally, it is well known that the electro-optic characteristics of LCDs, such as transmittance and threshold voltage, also rely on the LCD switching modes. The temperature dependence of the electro-optic characteristics of the wide-viewing-angle LCD modes, such as in-plane switching (IPS), multidomain vertical alignment by patterned electrode (PVA), and fringe-field switching (FFS), have been studied, and the results showed that the FFS mode has lower temperature dependence compared to the IPS and PVA modes. Since the liquid crystal (LC) reorients in different ways in each mode, this result is associated with the temperature dependence of LC's bend and twist elastic constants, and also with the position of the main reorientation, either in the middle or on the surface of the LC layer.

Viewing angle controllable in-plane switching liquid crystal display using one panel

  • Kim, Jin-Ho;Lim, Young-Jin;Her, Jung-Hwa;Srivastava, Anoop Kumar;Park, Kyoung-Ho;Lee, Joun-Ho;Kim, Byeong-Koo;Lee, Seung-Hee
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2009.10a
    • /
    • pp.629-632
    • /
    • 2009
  • We have proposed a novel viewing angle controllable display of in-plane switching (IPS) mode with single panel. One pixel of this device is divided to two regions, in which main pixel shows image and sub pixel for viewing angle control. In initial state, the liquid crystal of sub pixel is homogeneous aligned on substrate for wide viewing angle mode. On the other hand, after applying voltage, the liquid crystal of sub pixel tilts up for narrow viewing angle mode. The proposed device has advantage for the function for simple manufacturing process and good viewing angle control with single panel.

  • PDF

Effect of the Processing History on the Morphology and Properties of the Ternary Blends of Nylon 6, a Thermotropic Liquid Crystalline Polymer, and a Functionalized Polypropylene

  • Yongsok Seo;Kim, Hyong-Jun;Kim, Byeongyeol;Hong, Soon-Man;Hwang, Seung-Sang;Kim, Kwang-Ung
    • Macromolecular Research
    • /
    • v.9 no.4
    • /
    • pp.238-246
    • /
    • 2001
  • Properties of ternary blends of nylon 6 (Ny6), a thermotropic liquid crystalline polymer (TLCP, poly(ester amide), 20 wt%) and a maleic anhydride grafted polypropylene (2 wt%) (MAPP) were studied under various processing conditions. TLCP was pre-blended with MAPP first and then the binary one blended again with Ny6. The processing temperature of the second mixing was varied. Thermal properties show the partial miscibility of the ternary blend. The morphology of the TLCP phase in the first blending shows mostly in the fibril bundle shape, but varies between droplets and oriented fibrils after the second processing. Some of TLCP phase lost the fibril morphology during the second processing stage. The morphology variation invokes the change in tensile properties. Low extrusion temperature (270$\^{C}$) provides more fibril shapes, which are associated with less deformation in the second stage. The processing temperature effect was more evident when the draw ratio was high. High drawing was applicable due to the stabilizing action of tile compatibilizer.

  • PDF

Sensing and Interfacial Evaluation of Ni Nanowire Strands/Polymer Composites using Electro-micromechanical Technique (Electro-Micromechanical 시험법을 이용한 Ni Nanowire Strands 강화 고분자 복합재료의 Sensing과 계면 물성 평가)

  • Kim, Sung-Ju;Jung, Jin-Gyu;Park, Joung-Man
    • Proceedings of the Korean Society For Composite Materials Conference
    • /
    • 2005.11a
    • /
    • pp.141-144
    • /
    • 2005
  • Sensing and interfacial evaluation of Ni nanowire strands/polymer composites were investigated using Electro-micromechanical technique. Electro-micromechanical techniques can be used as sensing method for micro damage, loading, temperature of interfacial properties. Using Ni nanowire strands/silicone composites with different content, load sensing response of electrical contact resistivity was investigated under tensile and compression condition. The mechanical properties of Ni nanowire strands with different type/epoxy composites were measured using uniformed cyclic loading and tensile test. Ni nanowire strands/epoxy composites showed humidity and temperature sensing within limited ranges, 20 vol% reinforcement. Some new information on temperature and humidity sensing plus loading sensing of Ni nanowire strands/polymer composites could be obtained from the electrical resistance measurement as a new concept of the nondestructive interfacial evaluation.

  • PDF

High Temperature Size Exclusion Chromatography

  • Cho Hee-Sook;Park Soo-Jin;Ree Moon-Hor;Chang Tai-Hyun;Jung Jin-Chul;Zin Wang-Cheol
    • Macromolecular Research
    • /
    • v.14 no.3
    • /
    • pp.383-386
    • /
    • 2006
  • High temperature size exclusion chromatography (SEC) has been used widely for the characterization of crystalline polymers, for which high temperature operation above the polymer melting temperature is required to dissolve the polymers. However, this high temperature operation has many advantages in SEC separation in addition to merely increasing polymer solubility. At high temperature the eluent viscosity decreases, which in turn decreases the column backpressure and increases the diffusivity of the analytes. Therefore, many reports on the high temperature operation of high performance liquid chromatography (HPLC) have focused on shortening the analysis time and enhancing the resolution. However, the application of high temperature SEC analysis to exploit the merits of high temperature operation is scarce. In this article, therefore, we report on a new apparatus design for high temperature SEC.

The Alignment of Liquid Crystals on the Film Surfaces of Soluble Aromatic Polyimides Bearing t-Butylphenyl and Trimethylsilylphenyl Side Groups

  • Hahm, Suk-Gyu;Jin, Kyeong-Sik;Park, Sam-Dae;Ree, Moon-Hor;Kim, Hyung-Sun;Kwon, Soon-Ki;Kim, Yun-Hi
    • Macromolecular Research
    • /
    • v.17 no.12
    • /
    • pp.976-986
    • /
    • 2009
  • With the study goal of firstly elucidating the anisotropic interactions between oriented polymer chain segments and liquid crystal (LC) molecules, and secondly of determining the contributions of the chemical components of the polymer segments to the film surface topography, LC alignment, pretilt, and anchoring energy, we synthesized three dianhydrides, 1,4-bis(4'-t-butylphenyl)pyromellitic dianhydride (BBPD), 1,4-bis(4'-trimethylsilylphenyl)pyromellitic dianhydride(BTPD), and 2,2'-bis(4"-tert-butylphenyl)-4,4',5,5'-biphenyltetracarboxylic dianhydride (BBBPAn), and a series of their organosoluble polyirnides, BBPD-ODA, BBPD-MDA, BBPD-FDA, BTPD-FDA, and BBBPAn-FDA, which contain the diamines 4,4'-oxydianiline (ODA), 4,4'-methylenediamine (MDA), and 4,4'-(hexafluoroisopropylidene)dianiline (FDA). All the polyimides were determined to be positive birefringent polymers, regardless of the chemical components. Although all the rubbed polyimide films exhibited microgrooves which were created by rubbing process, the film surface topography varied depending on the polyimides. In all the rubbed films, the polymer chains were unidirectionally oriented along the rubbing direction. However, the degree of in-plane birefringence in the rubbed film varied depending on the polyimides. The rubbing-aligned polymer chains in the polyimide films effectively induced the alignment of nematic LCs along their orientation directors by anisotropic interactions between the preferentially oriented polymer chain segments and the LCs. The azimuthal and polar anchoring energies of the LCs ranged from $0.45{\times}10^{-4}\;-\;1.37{\times}10^{-4}\;J/m^2$ and from $0.86{\times}10^{-5}\;-\;4.26{\times}10^{-5}\;J/m^2$, respectively, depending on the polyimides. The pretilt angles of the LCs were in the range $0.10-0.62^{\circ}$. In summary, the soluble aromatic polyimides reported here are promising LC alignment layer candidates for the production of advanced LC display devices.

Fabrication of Pre-Exfoliated Clay Masterbatch via Exfoliation-Adsorption of Polystyrene Nanobeads

  • Khvan, Svetlana;Kim, Jun-Kyung;Lee, Sang-Soo
    • Macromolecular Research
    • /
    • v.15 no.1
    • /
    • pp.51-58
    • /
    • 2007
  • The approach studied in the present work produced an exfoliated state of clay layers via confinement of the charged nano-sized polystyrene (PS) beads within the gallery of swollen pristine clay. It was demonstrated that adsorption of the polymer nanobeads dramatically promotes expansion of the clay gallery. A comparative study of incorporation was conducted by employing organo-modified clay along with two different colloid polymer systems: electrostatically stabilized PS nanobeads and cationic monomer-grafted PS nanobeads. The mechanism of adsorption of the monomer-grafted polymer beads onto clay via cationic exchange between the alkyl ammonium group of the polymer nanobeads and the interlayer sodium cation of the layered silicate was verified by using several techniques. As distinct from the polymer nanobeads formed using conventional miniemulsion polymerization method, competitive adsorption of stabilizing surfactant molecules was be prevented by grafting the surface functional groups into the polymer chain, thereby supporting the observed effective adsorption of the polymer beads. The presence of surface functional groups that support the establishment of strong polymer-clay interactions was suggested to improve the compatibility of the clay with the polymer matrix and eventually play a crucial role in the performance of the final nanocomposites.

Development of Automated Diffusion Cell for Determining In Vitro Drug Release from Transdermal Device (경피흡수제형의 in vitro 약물방출실험을 위한 연속확산 장치의 개발)

  • Byun, Young-Rho;Choi, Young-Kweon;Jeong, Seo-Young;Kim, Young-Ha
    • YAKHAK HOEJI
    • /
    • v.34 no.3
    • /
    • pp.161-165
    • /
    • 1990
  • An automated, simple, and reliable method was developed for determining in vitro drug release rate from transdermal delivery dosage forms. The patch is held in position in the heating block by sandwiching it between the middle plate and the bottom plate of diffusion cell. The dissolution profile of the commercially available transdermal scopolamine patch was determined over a 72-h period, and the results were compared with those obtained with other methods; paddle-over-disk method, reciprocating method, and diffusion cell method. It was demonstrated that the flow-through method is equivalent in terms of release rate profile and accumulated released drug amount over the lifetime of the dosage form tested. Also this method is simple, reliable and reproducible. Therefore, this technique can be used in a quality control for assuring product uniformity.

  • PDF

Optimization of Cure System for the ESBR Silica WMB and BR Silica DMB Blend Compounds

  • Yu, Eunho;Kim, Woong;Ryu, Gyeongchan;Ahn, Byungkyu;Mun, Hyunsung;Hwang, Kiwon;Kim, Donghyuk;Kim, Wonho
    • Elastomers and Composites
    • /
    • v.54 no.2
    • /
    • pp.97-104
    • /
    • 2019
  • Emulsion styrene-butadiene rubber silica wet masterbatch (ESBR silica WMB) technology was studied to develop highly filled and highly dispersed silica compounds, involving the preparation of a composite by co-coagulating the modified silica and the rubber latex in a liquid phase. Previous studies have shown that when manufacturing ESBR silica WMB/Butadiene silica dry masterbatch (BR silica DMB) blend compounds, preparing BR silica dry masterbatch and mixing it with ESBR silica WMB gave excellent results. However, WMB still has the problem of lower crosslink density due to residual surfactants. Therefore, in this study, tetrabenzylthiuram disulfide (TBzTD) was added instead of diphenyl guanidine (DPG) in the ESBR silica WMB/BR silica DMB blend compounds and sulfur/CBS contents were increased to evaluate their cure characteristics, crosslink densities, mechanical properties, and dynamic viscoelastic properties. TBzTD was found to be more effective in increasing the crosslink density and to produce superior properties compared to DPG. In addition, with increasing sulfur/CBS contents, mechanical properties and rolling resistance were enhanced due to high crosslink density, but the abrasion resistance was not significantly changed because of the toughness.