Effect of acetyl substitution on the optical anisotropy of cellulose acetate films

Hatamoto, Kazuya; Shimada, Hikaru; Kondo, M.; Nobukawa, Shogo; Yamaguchi, Masayuki

doi:10.1007/s10570-018-1890-4

Cited by 9 publications

(6 citation statements)

References 24 publications

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“…Namely, as the temperature rises, G ′ decreases slowly first followed by a drastic decline due to the glass-to-rubber translation. The difference lies in that a slight increase in G ′ at high temperatures can be identified for 5CB0 probably due to the formation of microcrystalline. , Since the addition of 5CB molecules reduce the crystallization ability of CTA, this phenomenon is not observed for 5CB5, 5CB10, and 5CB15 . The value of T g can be determined from the evolution of the tan δ curves with the temperature.…”

Section: Resultsmentioning

confidence: 99%

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Orientation Birefringence Regulation for the Binary Blend Film of Cellulose Triacetate and Rigid-Rod-Like 5CB Molecules

Min

Han

et al. 2021

ACS Appl. Polym. Mater.

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By physical blending of the rigid-rod-like 4-cyano-4′-pentylbiphenyl (5CB) molecule with the cellulose triacetate (CTA), we have prepared the CTA/5CB blend films with different weight fractions of 5CB molecules (ω 5CB ) ranging from 0 to 15%. Even if only a small amount of 5CB molecules are added to the CTA matrix, the orientation birefringence of the stretched blend films becomes positive. With the increasing ω 5CB and the strain ε, the orientation birefringence gets significantly increased. The orientation degrees of CTA chains and 5CB molecules in the stretched blend films are acquired from the infrared dichroism measurements. Then, the nematic interaction strength between CTA chains and 5CB molecules is evaluated to be about 0.43. As ω 5CB ≥ 10%, aggregation of 5CB molecules occurs in the stretched blend films, while it does not affect the transmittance of films. We further show that the aggregation can improve the orientation birefringence of blend films significantly because of the strong nematic interaction between 5CB molecules. A physical picture at the molecular level is proposed to explain why the orientation birefringence of the stretched blend films gets increased. Finally, the orientation birefringence diagrams of the pure CTA films and the CTA/5CB blend films stretched at two different temperatures (170 and 200 °C) in the strain weight fraction of 5CB molecule (ε-ω 5CB ) space are established. We expect that these diagrams would provide a great potential guiding significance for the fabrication of CTA retardation films with specific values of orientation birefringence (Δn in ), such as quarter-wave film and half-wave films.

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Section: Resultsmentioning

confidence: 99%

“…It has been verified by a previous work that the acetyl group contributes a negative birefringence, while the hydroxyl group contributes a positive birefringence. 49 Thus, the higher content of the hydroxyl group accounts for the smaller absolute value of Δn in for 5CB0 film.…”

Section: Mechanical Propertiesmentioning

confidence: 96%

Orientation Birefringence Regulation for the Binary Blend Film of Cellulose Triacetate and Rigid-Rod-Like 5CB Molecules

Min

Han

et al. 2021

ACS Appl. Polym. Mater.

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“…These derivatives can be processed into highly transparent films that are commonly used in packaging. [40][41][42] Cellulose micro-and nanomaterials are undissolved fibers or fiber fragments that may or may not be colloidally stable, depending on their characteristic dimensions and surface compositions. Common plant-based cellulose micro-and nanomaterials include microcrystalline cellulose (MCC), cellulose nanofibrils (CNF), cellulose nanocrystals (CNC), holocellulose nanofibrils (holo-CNF), and lignocellulosic nanofibrils (ligno-CNF).…”

Section: Introductionmentioning

confidence: 99%

Plant‐Based Structures as an Opportunity to Engineer Optical Functions in Next‐Generation Light Management

et al. 2021

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This review addresses the reconstruction of structural plant components (cellulose, lignin, and hemicelluloses) into materials displaying advanced optical properties. The strategies to isolate the main building blocks are discussed, and the effects of fibrillation, fibril alignment, densification, self‐assembly, surface‐patterning, and compositing are presented considering their role in engineering optical performance. Then, key elements that enable lignocellulosic to be translated into materials that present optical functionality, such as transparency, haze, reflectance, UV‐blocking, luminescence, and structural colors, are described. Mapping the optical landscape that is accessible from lignocellulosics is shown as an essential step toward their utilization in smart devices. Advanced materials built from sustainable resources, including those obtained from industrial or agricultural side streams, demonstrate enormous promise in optoelectronics due to their potentially lower cost, while meeting or even exceeding current demands in performance. The requirements are summarized for the production and application of plant‐based optically functional materials in different smart material applications and the review is concluded with a perspective about this active field of knowledge.

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“…Therefore, novel techniques to control optical properties—such as extraordinary wavelength dispersion, 4–9 three‐dimensional refractive index control, 10–13 low photoelastic birefringence in the glassy state, 12,14–19 and modification of polarizability anisotropy through electrostatic interaction with ions 20–22 are being developed rapidly. The most important and fundamental technique used to meet these demands is the precise control of orientation, which is generally achieved by hot‐stretching 23–26 . This procedure affects not only optical retardation but also its wavelength dispersion 11,25 …”

Section: Introductionmentioning

confidence: 99%

“…The most important and fundamental technique used to meet these demands is the precise control of orientation, which is generally achieved by hot‐stretching 23–26 . This procedure affects not only optical retardation but also its wavelength dispersion 11,25 …”

Section: Introductionmentioning

confidence: 99%

Origin of stress and birefringence generation at hot‐stretching of poly(methyl methacrylate) containing low‐molecular‐weight compound

Yamaguchi

Miyashita

2020

J of Applied Polymer Sci

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The simultaneous measurements of stress and birefringence during hotstretching, and after the cessation of stretching, were performed using a miscible blend of poly(methyl methacrylate) (PMMA) and 10 wt% of 4-cyano-4 0pentylbiphenyl (which is commonly known as 5CB). The birefringence of the blend exhibited anomalous behavior during stretching, that is, it initially decreased, then rapidly increased to a positive value. A concave curve with a minimum birefringence was prominent at low temperatures, during which PMMA determined birefringence. After passing the yield point, which corresponded to the minimum birefringence, the birefringence increased in proportion to the applied stress. That is to say, the stress-optical coefficient remained constant. In this region, the 5CB molecules oriented themselves with the PMMA chains, that is, there was nematic interaction. After stretching ceased, the stress initially decreased rapidly; during this period, the stress-optical coefficient was determined mainly by the deformation of PMMA, that is, glassy component. Subsequently, the orientation relaxation of 5CB, which occurred with the orientation relaxation of PMMA chains in the stage with a long time region, determined the birefringence. These results demonstrated that nematic interaction does not occur when inelastic deformation is governed.

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Effect of acetyl substitution on the optical anisotropy of cellulose acetate films

Cited by 9 publications

References 24 publications

Orientation Birefringence Regulation for the Binary Blend Film of Cellulose Triacetate and Rigid-Rod-Like 5CB Molecules

Orientation Birefringence Regulation for the Binary Blend Film of Cellulose Triacetate and Rigid-Rod-Like 5CB Molecules

Plant‐Based Structures as an Opportunity to Engineer Optical Functions in Next‐Generation Light Management

Origin of stress and birefringence generation at hot‐stretching of poly(methyl methacrylate) containing low‐molecular‐weight compound

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