The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform
Xiaoli Zhang - One of the best experts on this subject based on the ideXlab platform.
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study on structure and orientation action of polyurethane nanocomposites
Macromolecules, 2004Co-Authors: Jain Xu, Yonglai Lu, Deyan Shen, Ning Zhao, Xiaoli ZhangAbstract:Segmented polyether−polyurethane (PU)/montmorillonite nanocomposites have been synthesized with poly(tetramethylene glycol), 4,4-diphenylmethane diisocyanate, propylenediamine, and montmorillonite. The nanoscale silicate layers are intercalated or exfoliated in the PU matrix, which are characterized by X-ray diffraction pattern and transmission electron microscopy. The PU/montmorillonite composites have been investigated by FT-IR Dichroism during the stretching process in order to study the hard and soft chain orientation, hydrogen bonding, and strain induced by crystallization of the soft segment chains in PU. DSC experiment indicates that the soft phase Tg increases with the montmorillonite content. The mechanical analysis showed that tensile strength,Young's modulus, and elongation at break increase markedly, 1700% elongation at break for the composite containing 2.0 wt % montmorillonite.
Jihoon Lee - One of the best experts on this subject based on the ideXlab platform.
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Optical anisotropy conversion of retarder film made of rodlike and crosslike reactive molecules, and its dependence on the relative ratio and the orientation of the constituent molecules
Optical Materials, 2020Co-Authors: Ho-jin Choi, Kwang-un Jeong, Jihoon LeeAbstract:Abstract We reported an optical anisotropy conversion of a retarder film composed of rodlike and crosslike reactive molecules. We investigated the dependence of the optical anisotropy of the composite film on the relative ratio and the orientation of the constituent molecules. We used the rodlike molecule as a host and the crosslike molecule as a guest. We prepared the retarder films which were composed of various concentration of the constituent molecules. The retarder film showed + c plate-like property when no guest was used. On the other hand, the optical anisotropy of the film was gradually changed to + b, z, and –b plate when the guest concentration was increased to 5, 10 and 20 wt%, respectively. From the Fourier Transform-Infrared (FT-IR) Dichroism measurement of the retarder films, it was found that the host molecules were vertically aligned when no guest was doped. The host molecules were tilted by doping the guest and then the in-plane optical anisotropy was shown. Consequently, the sign of the ratio of the out-of-plane optical anisotropy to the in-plane optical anisotropy was converted from negative to positive with its magnitude reduced.
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smectic a phase in a new bent shaped mesogen based on a 2 3 naphthalene central core with an acute subtended angle
Journal of Materials Chemistry, 2010Co-Authors: Ejoon Choi, Xin Cui, Changwoo Ohk, Wangcheol Zin, Jihoon Lee, Tongkun Lim, Wongun JangAbstract:A new bent-shaped molecule which consists of an acute-angled central core and all-ester linking groups has been prepared: 2,3-naphthylene bis[4-(4-n-dodecyloxybenzoyloxy)benzoate]. Its mesomorphic properties have been investigated by DSC, polarizing microscopy, and X-ray diffraction measurements. Moreover, we have carried out detailed electro-optical investigations including bIRefringence, switching current response, IR Dichroism, and second-harmonic generation (SHG) measurements. On the basis of the experimental data a plausible model for the mesophase alignments has been proposed.
Jain Xu - One of the best experts on this subject based on the ideXlab platform.
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study on structure and orientation action of polyurethane nanocomposites
Macromolecules, 2004Co-Authors: Jain Xu, Yonglai Lu, Deyan Shen, Ning Zhao, Xiaoli ZhangAbstract:Segmented polyether−polyurethane (PU)/montmorillonite nanocomposites have been synthesized with poly(tetramethylene glycol), 4,4-diphenylmethane diisocyanate, propylenediamine, and montmorillonite. The nanoscale silicate layers are intercalated or exfoliated in the PU matrix, which are characterized by X-ray diffraction pattern and transmission electron microscopy. The PU/montmorillonite composites have been investigated by FT-IR Dichroism during the stretching process in order to study the hard and soft chain orientation, hydrogen bonding, and strain induced by crystallization of the soft segment chains in PU. DSC experiment indicates that the soft phase Tg increases with the montmorillonite content. The mechanical analysis showed that tensile strength,Young's modulus, and elongation at break increase markedly, 1700% elongation at break for the composite containing 2.0 wt % montmorillonite.
Heino Finkelma - One of the best experts on this subject based on the ideXlab platform.
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liquid crystal elastomers influence of the orientational distribution of the crosslinks on the phase behaviour and reorientation processes
Macromolecular Chemistry and Physics, 1994Co-Authors: Jurge Kuupfe, Heino FinkelmaAbstract:The influence of the crosslinking conditions on the phase behaviour and reorientation processes of nematic elastomers is investigated. Two series of elastomers with various network anisotropies crosslinked either in the nematic or in the isotropic state were investigated by means of IR-Dichroism and stress-strain measurements. The experimental results clearly demonstrate that for nematic elastomers not only the coupling between the network anisotropy and the state of order has to be considered. It is shown that the influence of the crosslinks and theIR orientational distribution on the phase behaviour, the state of order as well as on dIRector reorientation processes cannot be neglected.
Yonglai Lu - One of the best experts on this subject based on the ideXlab platform.
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study on structure and orientation action of polyurethane nanocomposites
Macromolecules, 2004Co-Authors: Jain Xu, Yonglai Lu, Deyan Shen, Ning Zhao, Xiaoli ZhangAbstract:Segmented polyether−polyurethane (PU)/montmorillonite nanocomposites have been synthesized with poly(tetramethylene glycol), 4,4-diphenylmethane diisocyanate, propylenediamine, and montmorillonite. The nanoscale silicate layers are intercalated or exfoliated in the PU matrix, which are characterized by X-ray diffraction pattern and transmission electron microscopy. The PU/montmorillonite composites have been investigated by FT-IR Dichroism during the stretching process in order to study the hard and soft chain orientation, hydrogen bonding, and strain induced by crystallization of the soft segment chains in PU. DSC experiment indicates that the soft phase Tg increases with the montmorillonite content. The mechanical analysis showed that tensile strength,Young's modulus, and elongation at break increase markedly, 1700% elongation at break for the composite containing 2.0 wt % montmorillonite.
