Dynamic measurement of stress optical behavior of three amorphous polymers

Min, In-Ki; Yoon, Kyung Hoon

doi:10.1007/s13367-012-0008-z

Cited by 2 publications

(2 citation statements)

References 16 publications

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“…In addition, Hong et al conducted a comparative study on the transferability and birefringence distribution of the pattern through 7-inch LGP molding using the rapid injection-compression molding (RICM) process that combines the injection-compression process and rapid mold heating [4]. However, previous studies related to LGP mainly focused on optimization of optical patterns to increase luminance and uniformity and enhance the transcriptional properties of micropatterns during molding [5][6][7][8][9][10][11][12]. Interest in color reproducibility has recently started to increase, as this factor allows implementing more natural images while competing with display technologies such as OLED.…”

Section: Color Chromaticitymentioning

confidence: 99%

An Experimental Study on Color Shift of Injection-Molded Mobile LGP Depending on Surface Micropattern

2020

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In the display industry, the LCD backlight unit (BLU) module is variously used in mobile phones, notebook computers, monitors, and TVs. The light guide plate (LGP), which is one of the core parts of a BLU, is getting bigger and thinner consistently. Conventional injection methods and injection processes like injection compression molding (ICM) are becoming more complex and harsher with high-speed injection at high mold and melt temperatures. These approaches lead to a change in physical properties and a decrease in optical properties such as yellowing and color shift in injection-molded parts. In the present study, an injection molding experiment was conducted to understand the effect of surface patterns and major injection process conditions like mold and melt temperatures on the color shift in injection-molded mobile LGP. Optical properties obtained by the direct and total transmittance and CIE xy chromaticity diagram for injection-molded mobile LGP were measured with a UV–visible spectrophotometer. From the measurement of patternless LGP, it was found that total or direct transmittance was not affected by molding process variables. It was also found that yellow shift, ΔE(xy), occurred as much as 0.00111 ± 0.00014, and a color shift angle, Θ(xy), of 43.05 ± 2.44° was recorded in CIE coordinates for all nine experimental cases. From the measurement of total transmittance of patterned LGP, ΔE(xy) and Θ(xx) were found to be almost the same as those of patternless LGP for the locations of low and medium density of the pattern for the LGP, T1 and T2. The measured data of direct transmittance of patterned LGP showed that additional yellow shift due to scattering caused by surface micropattern. Interestingly, Θ(xy) of patterned data remained 43.05 ± 2.44°, which was almost the same as that found in the case of patternless LGP.

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Section: Color Chromaticitymentioning

confidence: 99%

An Experimental Study on Color Shift of Injection-Molded Mobile LGP Depending on Surface Micropattern

2020

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“…Recently, Min and Yoon performed frequency sweep tests to obtain the stress optical behavior in a wide range of frequency and temperature including rubbery, glassy, and glass transition regions for PS, PC, cyclic olefin copolymer (COC). In particular, they found that for COCs of different compositions exhibiting different values of

T_{g}

the stress‐optical coefficients in rubbery and glassy states was almost unaffected by the difference in composition.…”

Section: Introductionmentioning

confidence: 99%

Thermal birefringence in freely quenched multilayered slabs of amorphous polymers: Experiment and simulation

Kim

Isayev

2013

Polymer Engineering & Sci

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The simulation of the gapwise distribution of the thermally‐induced residual birefringence and stresses in freely‐quenched PS‐PC‐PS and PC‐PS‐PC multi‐layered slabs in water was carried out to calculate the gapwise distribution of the transient and residual birefringence. The modeling was based on the linear viscoelastic and photoviscoelastic constitutive equations combined with the first‐order rate equation for volume relaxation. The master curves for the Young's relaxation modulus and strain‐optical coefficient functions obtained earlier for PS and PC were used in the simulations. The obtained numerical results provided the evolution of the thermally‐induced stress and birefringence with time during and after quenching. The predicted gapwise residual birefringence distribution in these slabs was found to be in a fair agreement with the measured results. In addition, the gapwise distribution of the thermally‐induced residual birefringence in the multi‐layered PS‐PMMA‐PS, PMMA‐PS‐PMMA, PMMA‐PC‐PMMA, and PC‐PMMA‐PC slabs quenched from different initial temperatures was measured. Explanations were provided for the observed gapwise distribution of the thermal residual birefringence in each layer of these slabs including the effect of the initial temperature. POLYM. ENG. SCI., 54:2097–2111, 2014. © 2013 Society of Plastics Engineers

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Dynamic measurement of stress optical behavior of three amorphous polymers

Cited by 2 publications

References 16 publications

An Experimental Study on Color Shift of Injection-Molded Mobile LGP Depending on Surface Micropattern

An Experimental Study on Color Shift of Injection-Molded Mobile LGP Depending on Surface Micropattern

Thermal birefringence in freely quenched multilayered slabs of amorphous polymers: Experiment and simulation

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