Effect of KI Concentration in Correcting Tank on Optical Properties of PVA Polarizing Film

Abstract

Polarizer is a key component of the liquid crystal display panel, and the optical properties mainly include transmittance, degree of polarization and chromaticity. Polarizer is made of a multilayer optical film, in which the PVA polarizing film is the core structure for realizing the polarization of the whole polarizer. PVA polarizing film is commonly manufactured through a multi-step craft, including rinsing, dyeing, stretching and correcting. The correction process has a significant impact on the final apparent color and optical properties of the polarizer. In this study, the KI concentration in the correcting tank, ranging from 1% to 3%, was systematically investigated. With the increase in KI concentration, the Raman vibration peak at 160 cm−1 representing I5− ions gradually weakened, while the Raman vibration peak at 110 cm−1 representing I3− ions gradually increased, indicating that the KI in the correcting tank changed the chemical equilibrium of polyiodide ions in PVA. Then abundant chromophore I5− ions were consumed and I3− ions generated, so that the apparent color of PVA polarizing film gradually changed from dark blue to dark gray, and the chromaticity a-value and b-value gradually increased. The change in the concentration of dichroic species (I5− and I3−) in PVA polarizing film had directly affected its transmittance in the visible range. From the UV-Vis transmittance spectrum of PVA polarizing film, when the I5− ions were consumed and I3− ions generated, the transmittance of PVA polarizing film in the region of 675–525 nm wavelength increased gradually while the polarization degree also increased.

Antimicrobial Biomaterial on Sutures, Bandages and Face Masks with Potential for Infection Control

“…The UV-visible spectrum of AV-PVP-TCA-I 2 reveals absorption peaks of molecular I 2 (207 and 210 nm), iodide ions (202 nm) and triiodide ions (290 and 359 nm) ( Figure 6 , Table 2 ). Iodide ions, iodine molecules and triiodide ions are detected in accordance with previous investigations ( Figure 6 , Table 2 ) [ 15 , 22 , 23 , 25 , 27 , 30 , 33 , 34 , 36 , 41 , 42 , 89 , 90 , 91 , 100 , 101 , 102 , 103 , 104 ]. The bands at 290 and 359 nm depict a higher availability of symmetrical, linear triiodide ions (I-I-I − ) compared to asymmetric triiodide ions and iodine.…”

“…We used iodine, TCA and AV in our study to investigate the antimicrobial action against 10 selected pathogens. Iodine is a iodophor, which is most stable in form of “smart” triiodide species [ 34 , 36 , 41 , 42 , 100 , 101 , 102 , 103 , 104 ]. TCA, its derivatives and related AV bioconstituents, especially cinnamic acid, aloin, acemannan, aloe-emodin, pyrogallol, hesperidine, aloesin, 10-O-β-d-glucopyranosyl-aloenin and rhein increased biological activities due to their synergistic mechanisms [ 36 , 39 , 41 , 42 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 98 , 99 ].…”

“…The weakness of the absorption intensities is another indicator for the absence of pentaiodide ions. At the same time, free iodine is represented by a medium-sized shoulder at 171 cm −1 and further weak to very weak symmetric stretching modes up to 176 cm −1 in AV-PVP-TCA-I 2 ( Figure 5 , Table 1 ) [ 42 , 102 , 103 , 104 ]. The previous investigation with AV-PVP-Sage-I 2 was devoid of absorption modes around 172 cm −1 and free iodine molecules [ 42 , 102 , 103 , 104 ].…”

Effects of Plasticizing on Mechanical and Viscous Characteristics of Poly(vinyl alcohol): A Comparative Study between Glycerol and Diethanolamine

“…Poly(vinyl alcohol) (PVA) films have been widely utilized in optical devices as polarizers [1] for thin film transistor liquid crystal displays (TFT-LCDs) [2,3] because of their excellent transparency, DOI: 10.1002/mame.202300090 low polarity, and tight complexation, [4,5] achieved through iodine dyeing and highorientation stretching. [5] The universal steps for preparing PVA films include solvation, coating, stretching for tensile orientation, iodinated dyeing, [6] and so on, in which the viscosity [7] of PVA plays a crucial role, particularly for PVA with a high degree of polymerization.…”

Exploring the Interphase Structure of Poly(vinyl alcohol) during Sol–Gel Transition Using Selective Probes with Varied Molecular Sizes

“…Due to its high solubility feature in water, the water is normally used as the solvent to prepare PVA-based products in industry and laboratory. Taking the PVA film for the polarizer as an example, the PVA is first dissolved in the water at a high temperature ( T ∼ 150 °C), and then subsequently transferred onto the roll-to-roll processing. , During such a PVA film formation process, numerous phase transitions, i.e., sol–gel transition and PVA crystallization, happen simultaneously or in sequence. Structural parameters, such as the crystallinity of PVA and the mesh size ξ of the network, are closely related to the macroscopic performance of final PVA film products.…”