Liquid crystalline main chain polymers with a poly(p-phenylene terephthalate) backbone: 3. Drawing, structure development and ultimate mechanical properties of films of the polyester with dodecyloxy side chains

Damman, S.B.; Mercx, F. P. M.; Lemstra, Piet J.

doi:10.1016/0032-3861(93)90114-p

Cited by 24 publications

(14 citation statements)

References 6 publications

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“…This is due to the fact that the main chains become load-bearing. For the highest draw-ratios (A = 7) the modulus at -175°C equals the theoretically calculated modulus of about 50 GPa (for both modifications) [4].…”

Section: Resultssupporting

confidence: 50%

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Morphology and physical properties of a liquid–crystalline main‐chain polymer with flexible side chains

Damman¹,

Buijs²,

Mercx³

1994

Polymers for Advanced Techs

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A molecular laminate model is used to explain the properties of unoriented and oriented films of poly(p‐phenylene‐2,5‐didodecyloxyterephthalate) cast from solution. In oriented films the two different crystal modifications, A and B, give rise to room temperature tensile moduli of 15 and 30 GPa respectively. The packing (in clusters) of the side chains in modification A, leading to a glass–like transition in the side‐chain regions around −40°C, is largely responsible for this difference. Oriented films of modification A and B have coefficients of thermal expansion of +0.3×10−5 and −1× 10−5 K−1 respectively. It is concluded that the properties of this class of polymers can be adjusted in a systematic way.

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Section: Resultssupporting

confidence: 50%

“…It can be shown by X-ray diffraction that in PTA12HQ films cast from solution the main-chain layers extend parallel to the film surface [4,111. Upon drawing such a film at 200°C in the highly viscous [2] mesophase a macroscopic orientation can be obtained [4,11,121 yielding the structure shown in Fig. 2.…”

Section: Resultsmentioning

confidence: 99%

Morphology and physical properties of a liquid–crystalline main‐chain polymer with flexible side chains

Damman¹,

Buijs²,

Mercx³

1994

Polymers for Advanced Techs

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“…Their results indicated an increase in the molecular rigidity with a larger sequence of the p-phenylene units. Measurement of a low temperature modulus by Damman et al 5) determined a value that is very close to the theoretical value obtained by Tashiro and Kobayashi 6) which indicates a virtually perfect orientation of the chains at these low temperatures. Apparently, if the main chains remain in sufficient contact with each other in a layered structure, a fairly high modulus can be retained.…”

Section: Introductionmentioning

confidence: 74%

Dynamical simulated annealing for assessing the high performance nature of poly(ethersulfone)s

Madkour¹

1999

Angew. Makromol. Chem.

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In order to assess the high performance nature of poly(ethersulfone) or to provide an understanding of its molecular origin, stress‐strain measurements were carried out as a function of temperature for neat poly(ethersulfone) as well as its glass‐ and carbon‐reinforced composites. It was observed that the modulus of these samples has not dramatically changed when changing the temperature; instead, the tensile strength values changed on the expense of the elongation at break as to keep the modulus constant. Close inspection of the molecular‐level behavior of the material using molecular simulation techniques revealed that the distribution of the dihedral angles around the oxygen and sulfur atoms did not drastically change below the heat deflection temperature, possibly due to the rigidity of the polymeric chains. However, above that temperature the conformational change was evident as the chains exhibited more of the higher energy conformations. Young's modulus predicted for the polymer indicated a good agreement with the experimental observations thus suggesting the validity of the model to describe the real system. Other key elastic constants of the polymer, such as the Poisson values, Lame constants and the compressibility were also evaluated.

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“…12,13 All of the investigated polymers PPT-CZ10 with different molecular weights exhibit a clear melting transition at T m Ϸ 154°C, even if they reveal a different heat of melting ⌬H m and a different ␤ transition temperature T ␤ . 16 Therefore, we can conclude that the layered domains easily orient by a nonhomogeneous stress in the melt and thus exhibit an anisotropic morphology. Figure 2 shows the x-ray diffraction patterns and intensity profiles for PPT-CZ10 polymers.…”

Section: A Layered Photoconductive Polymer Ppt-czmentioning

confidence: 85%

Layered photoconductive polymers: Anisotropic morphology and correlation with photorefractive reflection grating response

Kwon

Jazbinšek

et al. 2006

The Journal of Chemical Physics

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We demonstrate that the mesophase morphology of the layered photorefractive polymers has a substantial influence on the photorefractive properties, especially in reflection grating geometries with a minimal grating spacing. The layered morphology of the photoconductive polymers based on poly(p-phenyleneterephthalate) (PPT) with pendent carbazole (CZ) groups can be efficiently controlled by changing their molecular weight. Photorefractive composites based on PPT-CZ polymers with different chromophores, diethylaminodicyanostyrene (DDCST) or piperidinodicyanostyrene (PDCST), show anisotropic morphology induced by the squeezing flow during sample preparation. The contributions of the highest occupied molecular orbital levels of the chromophores and of the degree and anisotropy of the layered crystalline structure to the charge transport and trapping result in a high efficiency of the PDCST composite and a similar response speed in DDCST and PDCST composites in the reflection grating geometry, although of about six times lower photoconductivity in the less-ordered PDCST composite.

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Liquid crystalline main chain polymers with a poly(p-phenylene terephthalate) backbone: 3. Drawing, structure development and ultimate mechanical properties of films of the polyester with dodecyloxy side chains

Cited by 24 publications

References 6 publications

Morphology and physical properties of a liquid–crystalline main‐chain polymer with flexible side chains

Morphology and physical properties of a liquid–crystalline main‐chain polymer with flexible side chains

Dynamical simulated annealing for assessing the high performance nature of poly(ethersulfone)s

Layered photoconductive polymers: Anisotropic morphology and correlation with photorefractive reflection grating response

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