Effect of polymer matrix glass transition temperature on polymer dispersed liquid crystal electro‐optics

1992 ◽  
Vol 60 (26) ◽  
pp. 3238-3240 ◽  
Author(s):  
J. L. West ◽  
J. R. Kelly ◽  
K. Jewell ◽  
Y. Ji
Keyword(s):  
Glass Transition ◽  
Liquid Crystal ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polymer Matrix ◽  
Matrix Glass ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed

Study of the effect of the reinforcement direction on the identification of relaxation transitions of moisture-saturated carbon fiber VKU-25

2021 ◽  
Vol 87 (9) ◽  
pp. 38-43
Author(s):  
O. G. Ospennikova ◽  
P. S. Marakhovsky ◽  
N. N. Vorobyov ◽  
E. V. Nikolaev ◽  
A. I. Gulyaev ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Carbon Fiber ◽  
Polymer Matrix ◽  
Structural Parameters ◽  
Polymer Materials ◽  
Thermal Coefficient ◽  
Initial State ◽  
Relaxation Transitions

Thermodilatometric methods of analysis are used to study the structural parameters of polymer materials, however, when studying moisture-saturated compositions certain difficulties arise in their identification. The results of thermophysical tests of VKU-25 carbon fiber samples in the initial state and after moisture saturation are presented. It is shown that heat treatment of materials affects the recorded values of the glass transition temperature of the epoxy matrix. When the samples are exposed in water or above the water surface, the sorbate penetrates into the polymer at the same rate, which is confirmed by almost identical values of water absorption at the same exposure time. The estimates of the thermal coefficient of linear expansion (TCLE) of the samples in the range of 20 - 250°C are given. Moreover, it is shown that the glass transition temperature of the plasticized polymer matrix depends on the direction of fiber reinforcement. In the case of moisture-saturated carbon fiber (CF)heated to 210°C, the formation of main cracks occurs mainly at the fiber-matrix interface. The glass transition temperature (GTT) of the material in the dry state (176 - 177°C), appeared almost independent on the heating rate, whereas for water-saturated samples, GTT changes significantly and can be described by a polynomial of the 2nd order. After exposure of the carbon fiber under conditions of high temperature and humidity, two relaxation transitions corresponding to the systems occur in the polymer matrix: epoxidian oligomer— amine hardener and polyfunctional resin— amine hardener. The glass transition temperature is 132 and 159°C in the first and in the second, respectively. The results obtained can be used in the development of new polymer composite materials.

Enhancement of Optical Transmittance of Polymer-Dispersed Liquid Crystal Cells

2015 ◽  
Vol 643 ◽  
pp. 29-32
Author(s):  
Intan Syazwani ◽  
Moriyoshi Haruyama ◽  
Hiroki Hachisuka ◽  
Gicho Sha ◽  
Wataru Kada ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Surface Treatment ◽  
Polymer Matrix ◽  
Optical Transmittance ◽  
Application Field ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed ◽  
Crystal Cells ◽  
Network Type

Enhancement of optical transmittance of polymer-dispersed liquid crystal (PDLC) cells was investigated by introducing a modification into the substrates. Surface treatment by rubbing was performed on both network-type and droplet-type PDLCs to investigate the effect on the optical transmittance of the cells. Differences in the transmittance of the PDLC in the polymer matrix were observed by introducing rubbing effect on network-type PDLC but not on droplet-type PDLC. These phenomena might be used to distinguish the application field of both types of PDLC cells by enhancing optical transmittance and scattering properties.

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