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Kajiyama, Tisato,Kikuchi, Hirotsugu,Jeong, Hwan Kyeong,Jeong, Noh Hee,Nam, Ki Dae 한국공업화학회 1998 Journal of Industrial and Engineering Chemistry Vol.4 No.3
The relationship between the polymer molecular weight and the electro-optical properties was investigated for the polymer/liquid crystal (LC) composite film prepared by a solvent-induced phase separation method. Poly(methyl methacrylate) (PMMA) and poly(diisopropyl fumarate) (Pdi-iPF) with significantly different weight-average molecular weight (M_w) were used as the matrix for the Polymer/LC composite film. It is confirmed from morphological observation by scanning electron microscope (SEM) that the size of LC channel or domain was strongly dependent on M_w of PMMA and Pdi-ipF. With increasing M_w in PMMA/LC composite film, the switching hysteresis was decreased due to a decrease of the compatibility at the polymer-LC interface. The hysteresis in (Pdi-iPF/LC) composite film was not detected for electro-optical switching and this result is not changed with MW of Pdi-iPF.
Activated Physical Properties at Air-Polymer Interface
Kajiyama, Tisato The Polymer Society of Korea 2007 Macromolecular Research Vol.15 No.2
The surface molecular motion of monodisperse polystyrene (PS) films was examined using scanning vis-coelasticity microscopy (SVM) in conjunction with lateral force microscopy (LFM). The dynamic storage modulus, E', and loss tangent, $tan\delta$, at a PS film surface with number-average molecular weights, $M_n$, smaller than 30 k were found to be smaller and larger than those for the bulk sample, even at room temperature, meaning that the PS surface is in a glass-rubber transition or fully rubbery sate at this temperature when the $M_n$ is small. In order to quantitatively elucidate the dynamics of the molecular motion at the PS surface, SVM and LFM measurements were performed at various temperatures. The glass transition temperature, $T_g$, at the surface was found to be markedly lower than the bulk $T_g$, and this discrepancy between the surface and bulk became larger with decreasing $M_n$. Such an intensive activation of the thermal molecular motion at the PS surfaces can be explained in terms of an excess free volume in the vicinity of the film surface induced by the preferential segregation of the chain end groups.
Kajiyama, Tisato,Kikuchi, Hirotsugu,Jeong, Hwan Kyeong,Jeong, Noh Hee 한국공업화학회 1997 Journal of Industrial and Engineering Chemistry Vol.3 No.4
Fluorine type low molecular weight liquid crystal(LC) dependence of the hysteresis of electrooptical switching and the phase-separated structure was investigated for the (polymer/LC) composite film cast from a uniform solution. It is confirmed from morphological observation by scanning electron microscopy (SEM) that the LC domain size of the composite film containing fluorine type LCs remarkably decreased. The interfacial phase-mixing behavior between polymer and LC components was evaluated by the time domain method based on the dielectric composite model of the (polymer/LC) composite film, the temperature dependence of the composite film and the atomic force microscopy (AFM). The hysteresis of electro-optical switching for the composite film was strongly dependent on the LC type. When the polymer and the LC were not compatible such as (Poly(methyl methacrylate)(PMMA)/fluorine type LC) composite system, the static hysteresis of the electro-optical switching for the composite film was not observed. It is found that the phase-mixing at the polymer-LC interface upon applying an a.c. electric field had great effect on the electro-optical switching hysteresis of the composite film.
Electron/muon specific two Higgs doublet model
Kajiyama, Y.,Okada, H.,Yagyu, K. North Holland 2014 Nuclear Physics, Section B Vol.887 No.-
We discuss two Higgs doublet models with a softly-broken discrete S<SUB>3</SUB> symmetry, where the mass matrix for charged-leptons is predicted as the diagonal form in the weak eigenbasis of lepton fields. Similarly to an introduction of Z<SUB>2</SUB> symmetry, the tree level flavor changing neutral current can be forbidden by imposing the S<SUB>3</SUB> symmetry to the model. Under the S<SUB>3</SUB> symmetry, there are four types of Yukawa interactions depending on the S<SUB>3</SUB> charge assignment to right-handed fermions. We find that extra Higgs bosons can be muon and electron specific in one of four types of the Yukawa interaction. This property does not appear in any other two Higgs doublet models with a softly-broken Z<SUB>2</SUB> symmetry. We discuss the phenomenology of the muon and electron specific Higgs bosons at the Large Hadron Collider; namely we evaluate allowed parameter regions from the current Higgs boson search data and discovery potential of such a Higgs boson at the 14 TeV run.
Synthesis and Miscibility Phenomena of Polyvinyl Butyral of Varying Vinyl Alcohol Contents
Kajiyama, Tisato,Karasz, Frank E,Rooney, Mikle,David, Don J,Jeong, Hwan Keong,MacKnight, Wiliam J 한국공업화학회 1998 응용화학 Vol.2 No.1
Polyvinyl butyrals(PVBs) of systematically varying vinyl alcohol content have been synthesized and characterizing using wet chemistry, IR, DSC and TGA. The miscibility of polyvinyl hutyral(PVB)/polymethyl methacrylate(PMMA) blends was studied by DSC, DMTA and SEM as a function of PMMA and vinyl alcohol(VA) content differences between the respective blend components. It is found that a blend of PVB containing 23 wt% VA with PMMA at a weight ratio of 80:20, repectively, was thermodynamically miscible. The miscibility parameter(MP) model used to estimate potential areas of compatibility/miscibility is based on the use of solubility parameters and the estimated region of compatibility/miscibility agrees with the experimental results.