Novel Liquid Crystal Polymers with Tailored Chemical Structure for High Barrier, Mechanical and Tribological Performance

Komatsu, Shintaro; Wetzel, Bernd; Friedrich, K.

doi:10.1007/978-3-319-20270-9_2

Cited by 5 publications

(5 citation statements)

References 29 publications

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“…In Hall and Knoff, 8 the total degradation was purely thermal, so no hydrolysis was considered. Results for the assessment of the aging of liquid crystal polymer (LCP) are found in Komatsu et al 10 ; however their results are not based in seawater submersion and studies regarding this specific type of aging in LCP are rare in the literature. Among the most commonly used polymers used in mooring ropes, polyethylene terephthalate is found to be the most frequently tested to hydrolysis, both in pure or seawater.…”

Section: Introductionmentioning

confidence: 99%

Lifetime prediction of aramid yarns applied to offshore mooring due to purely hydrolytic degradation

Duarte

Guilherme

Silva

et al. 2019

Polymers and Polymer Composites

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The discovery of oil fields in deepwater over the last decades led the oil and gas industry to the necessity of replacing the steel wire cables of the mooring systems of offshore platforms by polymeric ropes. These systems must be designed to work for at least 20 years without showing substantial loss in tensile strength or in their mechanical behavior along this period. However, some polymers present degradation by seawater through the process of hydrolysis, and the question whether it affects significantly the materials’ ultimate tensile strength arises. Accelerated hydrolysis tests were conducted in yarn samples of aramid at high temperature in order to use the Arrhenius correlation to predict their lifetime under service conditions. In order to decouple the total degradation into a thermal and a purely hydrolytic part, separate aging experiments were performed into a dry chamber and the conclusion was that thermal degradation does not play a significant role in the total degradation of aramid due to the water submersion at the temperatures tested.

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Section: Introductionmentioning

confidence: 99%

Lifetime prediction of aramid yarns applied to offshore mooring due to purely hydrolytic degradation

Duarte

Guilherme

Silva

et al. 2019

Polymers and Polymer Composites

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“…The CF/PA-PU containing 5 wt.% LCP shows a 16.06% decrease in COF (0.183), and exhibits the lowest scar width (5.75 mm) and wear rate (7.11 × 10 −9 •cm 3 •(N•M) −1 ), about 7.26% and 32.22% lower than those of the CF/PA-PU composite. The excellent tribological properties of the LCP/CF/PA-PU composite were attributed to a synergistic effect between the superior self-enhancement properties of LCP and probably a rolling effect induced by chopped CF [30]. LCP could form highly oriented crystalline structures, i.e., liquid crystalline microfibrils, when subjected to shear flow above its melting point.…”

Section: Tribological Propertiesmentioning

confidence: 99%

“…In addition, the trend of energy consumption is consistent with that of the equilibrium torque, from 0.472 KNm•g −1 for CF/PA-PU to 0.401 KNm•g −1 for 7%LCP/CF/PA-PU. The lower melt viscosity is beneficial for the uniform dispersion of carbon fibers and the formation of liquid crystal microfibrils, which could promote the interfacial bonding between the polymer matrix and carbon fibers [30], thus further improving the mechanical and tribological properties of LCP/CF/PA-PU composites. Furthermore, Figure 8a indicates that the equilibrium temperature of the composite melts hardly deviates from the set temperature with the addition of LCP, which could ensure the stability of the composites throughout the production processes.…”

Section: Processing Propertiesmentioning

confidence: 99%

Tribological and Mechanical Applications of Liquid-Crystal-Polymer-Modified Carbon-Fiber-Reinforced Polyamide–Polyurethane Composites

Zhou

Wang

et al. 2023

Polymers

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An aromatic copolyester liquid crystal polymer (LCP) was introduced into carbon-fiber-reinforced polyamide–polyurethane (CF/PA-PU) composites through melt blending to improve the tribological properties of the composites. The effects of LCP on the mechanical, processing, and thermal properties of CF/PA-PU composites were compared to those of commonly-used graphite (Gr). The results showed that at 5 wt.% LCP content, the coefficient of friction (COF) was decreased by 16.06%, and the wear rate by 32.22% in the LCP/CF/PA-PU composite compared to the CF/PA-PU composite. Furthermore, using LCP instead of Gr showed significantly improved mechanical properties and reduced processing viscosity. The tensile strength of 5%LCP/CF/PA-PU composite could reach 99.08 MPa, while the equilibrium torque was reduced, being 26.85% higher and 18.37% lower than those of CF/PA-PU composite, respectively. The thermal stability of LCP/CF/PA-PU composites was also enhanced. The addition of 5 wt.% LCP to CF/PA-PU composite increased the initial decomposition temperature by 14.19% compared to CF/PA-PU. In sharp contrast, the addition of Gr increased equilibrium torque and actual processing temperature leading to processing difficulties and instability. This approach offers a novel strategy for tribological applications and tackles the problem of high viscosity in CF/PA-PU composites.

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“…This is because heat treating a polymer below its melting point affects the molecular structure, thereby increasing the crystallinity and improving the physical properties 16 – 19 . By improving their moisture-resistance and performance in extreme low-temperature environments through heat treatment, TLCPs can be used for various applications, including marine ropes, cables, fishing nets, sports nets, printed circuit boards, aerospace, and military composite materials that require extreme performance 20 , 21 .…”

Section: Introductionmentioning

confidence: 99%

Annealing effect of thermotropic liquid crystalline copolyester fibers on thermo-mechanical properties and morphology

Park

Kim

et al. 2022

Sci Rep

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A series of thermotropic liquid crystal copolyesters (Co-TLCPs) was prepared by melt polymerization using 2,5-diethoxyterephthalic acid (DTA), 2,7-dihydroxynaphthalene (DHN), and p-hydroxybenzoic acid (HBA) monomers, where the HBA content was varied (0–5 mol). At 3 mol HBA, the Co-TLCPs formed nematic mesophases, while below this concentration, the liquid crystalline phase did not appear. The Co-TLCP sample with 3 mol HBA was subjected to melt spinning and heat-treated under various conditions (temperature and time) to investigate their effect on the thermo–mechanical properties and degree of crystallinity. The objective was to determine the critical heat treatment condition that can maximize the properties of the spun Co-TLCP fibers. The microstructure of the heat-treated fiber was investigated using scanning electron microscopy, and the optimal annealing conditions were confirmed based on the morphology of the fiber, which exhibited a skin–core structure owing to the varying heat and pressure conditions applied during spinning.

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Novel Liquid Crystal Polymers with Tailored Chemical Structure for High Barrier, Mechanical and Tribological Performance

Cited by 5 publications

References 29 publications

Lifetime prediction of aramid yarns applied to offshore mooring due to purely hydrolytic degradation

Lifetime prediction of aramid yarns applied to offshore mooring due to purely hydrolytic degradation

Tribological and Mechanical Applications of Liquid-Crystal-Polymer-Modified Carbon-Fiber-Reinforced Polyamide–Polyurethane Composites

Annealing effect of thermotropic liquid crystalline copolyester fibers on thermo-mechanical properties and morphology

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