| With the development of LC technology, liquid crystal device has already intofamilies, also brought a lot of fun to people’s spare life. But the traditional liquidcrystal device has low contrast, high operating voltage, and need to add a polaroid,so light loss is very serious, so LC researchers spare no effort to solve these defects.Polymer dispersed liquid crystal device is good enough to solve the above problems.When Polymer dispersed liquid crystal works without an external voltage, LCrandom distribution in the polymer, so the refractive index of liquid crystal andpolymer mismatch, the incident light is widely scattered off, lead the PDLC film hasa very small amount of light transmittance. When add an external voltage, LCpointing vector varies with the direction of the voltage changes, then the LC of thepointing vector and electric field in the same direction, the refractive index ofpolymer and liquid crystal match well,so large amounts of light can be through thePDLC film, PDLC film is transparent. By the principle of polymer dispersed liquidcrystal, polymer dispersed liquid crystal device does not need a polaroid, this is cansolve the problem that LC device light utilization rate is not high, so the study ofPDLC devices have high practical significance, therefore, how to improve thecontrast of PDLC, reduce the operating voltage, improve PDLC electro-opticalproperties, are this article want to study.The materials of PDLC are the premise, after determine the experimentalmaterial, we adopt the Orthogonal design method to discuss the best processconditions, orthogonal design method is a good method to solve the experimentswhen the conditions are many. Through the orthogonal experiment analysis, wedetermine the optimum process conditions of the experiment taken: LC E7contentis80%; EB648: MMA to2:1; The I-184content is2%; Curing time is20minutes;of the thickness of liquid crystal box is15um. The obtained PDLC performance parameters of the process: CR is53.7; Maximum transmission rate was90.1%; Theminimum transmission rate was1.68%; Operating voltage1.2V. Then we analysisthe PDLC polarizing microscope images of various conditions to discuss the effectsof liquid crystal, polymer, the thickness of liquid crystal box, curing time on theproperties of PDLC.In the PDLC solution, adding different content of ferroferric oxidenanoparticles, we found that ferroferric oxide reduces transmissivity of PDLC, butreduces the operating voltage, the operating voltage down to0.6V, at the same timethe conductance of the PDLC will sharply rise, this is because ferroferric oxide hasmagnetic character, after the voltage is applied to it, electromagnetic inductionhappens, the nanoparticles approval to the electric field, that change the distributionof liquid crystal in the PDLC.Then we add titanium dioxide nanoparticles into the polymer dispersed liquidcrystal,studies have found that it can reduce the transmissivity of PDLC, but willgreatly improve the contrast of the PDLC,contrast can be up to155, this is mainlybecause adding titanium dioxide nanoparticles can decrease the refractive indexmatching degree of the polymer and liquid crystal, the maximum and minimumtransmission rate both decreased, but the impact on the minimum transmission ratewill be relatively large, so the contrast will be improved.Operating voltage and contrast are very important parameters of liquid crystalmaterials. By adding nanoparticles,we improved the performance of the PDLCoptimization, which indicate that the combination of nanometer materials and liquidcrystal has high practical significance. |
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