Hygroscopic Behavior of Woven Fabric Carbon-Epoxy Composites

Abot, Jandro L.; Yasmin, A.; Daniel, I. M.

doi:10.1177/0731684405043548

Cited by 47 publications

(28 citation statements)

References 26 publications

(23 reference statements)

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“…The samples are removed periodically to measure their mass and/or volume changes for a given amount of time, from weeks to years 10,[13][14][15][16][17] . The hygrothermal test may be followed by mechanical testing, i.e., residual static/fatigue strength/fracture mechanics testing [17][18][19] , which only gives information on the effect of hygrothermal stimulus on the mechanical responses of materials.…”

Section: Introductionmentioning

confidence: 99%

A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli

Gomez

Pires

Yambao

et al. 2014

JoVE

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The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs and condition-based maintenance. These materials are adopted in a wide range of engineering applications, from aircraft and ship structures, to bridges, wind turbine blades, biomaterials and biomedical implants. Polymers are viscoelastic materials, and their response may be highly nonlinear and thus make it challenging to predict and monitor their in-service performance. The laboratory-scale testing platform presented herein assists the investigation of the influence of concurrent mechanical loadings and environmental conditions on these materials. The platform was designed to be low-cost and user-friendly. Its chemically resistant materials make the platform adaptable to studies of chemical degradation due to in-service exposure to fluids. An example of experiment was conducted at RT on closed-cell polyurethane foam samples loaded with a weight corresponding to ~50% of their ultimate static and dry load. Results show that the testing apparatus is appropriate for these studies. Results also highlight the larger vulnerability of the polymer under concurrent loading, based on the higher mid-point displacements and lower residual failure loads. Recommendations are made for additional improvements to the testing apparatus. Video LinkThe video component of this article can be found at

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Section: Introductionmentioning

confidence: 99%

A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli

Gomez

Pires

Yambao

et al. 2014

JoVE

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“…This process is usually described by a differential mass balance, often called Fick's second law of diffusion. [9] A characteristic diffusion time (t D ) is proportional to h 2 /5D where h is the film thickness and D is diffusion coefficient. Therefore, the data in Figure 2a implies that the cured PEPEP50 films can have much lower diffusion coefficient because of the dense network of the polymer film, which reduces the free volume and chain relaxation in the film.…”

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confidence: 99%

Photocurable Organic Gate Insulator for the Fabrication of High‐Field Effect Mobility Organic Transistors by Low Temperature and Solution Processing

et al. 2007

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Demand for inexpensive electronic devices has driven interest in organic semiconductors that can be deposited by simple, low-cost, solution-based processes. [1][2][3][4][5][6][7] Moreover, this allows the use of flexible substrates such as plastics, opening a route for the development of flexible, thin film electronic devices and information displays with the advantages of light weight, low cost, and low-temperature processing, which is a much sought-after goal. The potential applications of organic semiconductors have generated intense research interest in organic thin film transistors (OTFTs). To form a well-defined interface between the organic semiconductor and the gate insulator during solution processing, the gate insulator should not be soluble in the solvent used to dissolve the organic semiconductor. Although thermal curing can be used to prepare insoluble organic gate insulators, a high temperature process is still necessary to complete the chemical crosslinking, and this process distorts the plastic substrate.[8] Here we introduce a photo-curable organic gate insulator for OTFTs that allows low-temperature and solution-based processing and provides high field-effect mobility in the devices. This photo-curable organic insulator can be patterned easily to make connections (i.e. vertical interconnectivity via holes) between the gate electrodes and the underlying bus lines in integrated circuits. This patterning is achieved using a simple conventional photolithography process (i.e. photo-irradiation through a photomask and developing), and does not require the complicated lithography process typically used to pattern via holes during OTFT array fabrication (i.e. photolithography using a photoresist, oxygen plasma etching, and lift-off method). Therefore, use of the insulator described here can simplify the fabrication of integrated circuit devices. When we used this organic insulator in pentacene TFTs, we observed a high field-effect mobility of 0.5 cm 2 V -1 s -1 without hysteresis, and an on/off current ratio of 1.7 × 10 7 , when we used a polycrystalline pentacene with a bottom-contact geometry as the semiconductor. The organic insulator was prepared from a blend of 49.5 wt % poly(4-vinylphenol) (PVP) (Aldrich Co.) as the radical initiator and 49.5 wt % trimethylolpropane triglycidyl ether (Aldrich Co.) as the crosslinker, 0.5 wt % benzoyl peroxide (Aldrich Co.), and 0.5 wt % triphenylsulfonium triflate (Uray Co.) as the photoacid generator (PAG) (Fig. 1a). After spin-casting from a 10 wt % solution of the mixture (referred to hereinafter as PVPEP50) in cyclohexanone, the film was first soft-baked to remove the residual solvent on a hot plate at 100°C for 5 min, and then exposed to a 600 W UV light for 10 min to promote cross-linking in the film via a reaction involving the epoxy groups. Finally the film was baked at 100°C for an additional 30 min to harden the film. With irradiation, network formation occurs by the photoinduced acid-catalyzed reaction between PVP and the epoxy-containing crosslinker. T...

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Efeito higrotérmico em prepregs de fibra de vidro/epóxi por espectroscopia de luminescência

Sales

Dibbern-Brunelli

2008

Polímeros

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dependendo das condições de temperatura, umidade relativa e tempo de exposição, é considerável, uma vez que tanto a resina epoxídica como a fibra de vidro contém grupos polares [2] . A água se difunde tanto na matriz polimérica como na região de interfase fibra-matriz. Na matriz polimérica, a água pode atuar como plastificante aumentando o volume livre e, conseqüentemente, diminuindo a temperatura de transição vítrea. Pode então ocorrer uma diminuição da rigidez e re- IntroduçãoCompósitos de fibra de vidro/epóxi apresentam excelente compatibilidade entre seus componentes, favorecendo a sua aplicação crescente em peças estruturais primárias e secundárias de aeronaves. No entanto, a absorção de umidade de água por laminados de compósitos de fibra de vidro e resina epoxídica pode influenciar significativamente as propriedades mecânicas destes materiais [1] . Resumo: O objetivo deste trabalho é o estudo do efeito higrotérmico em pré-impregnados (prepreg) não curados de fibra de vidro-resina epoxídica usando a técnica de espectroscopia eletrônica de luminescência em modo estacionário. O método de fluorescência extrínseca foi empregado utilizando-se a sonda 9-ácido antróico (9-AA), cujo comportamento fotofísico depende fortemente da polaridade do meio. As amostras foram submetidas a umidades relativas de 6 e 84% por meio da utilização de soluções aquosas saturadas de hidróxido de sódio a 34,5 °C e cloreto de potássio a 20,0 °C, em recipientes fechados, pelos períodos de tempo de 1 semana, 15 dias e 1 mês. As amostras submetidas à umidade relativa de 6% apresentaram aumento significativo das intensidades relativas dos espectros de fluorescência em relação à amostra referência. Este comportamento fotofísico foi atribuído à presença da forma protonada do 9-AA no meio devido à reticulação da matriz polimérica. Após 1 mês, o espectro de emissão apresenta uma diminuição da intensidade em seu máximo. Isto ocorreu provavelmente devido ao processo de plastificação da matriz polimérica promovido pela presença de água na matriz, confirmado pela análise gravimétrica. Os espectros de fluorescência extrínseca das amostras submetidas à umidade relativa de 84% apresentaram as seguintes modificações espectrais: a) decaimento da intensidade de emissão das curvas b e d; b) deslocamento da banda de emissão para a região do azul devido ao aumento do teor de água; e c) aparecimento de um ombro na banda de emissão em 424 e 472 nm. Este comportamento fotofísico foi atribuído ao deslocamento do equilíbrio químico da forma protonada para a forma ionizada do 9-AA, promovido pela entrada de umidade no material. Palavras-chave: Espectroscopia de Luminescência, efeito higrotérmico, prepreg, 9-ácido antróico. Hygrothermal Effect In Glass Fiber/Epoxy By Luminescence SpectroscopyAbstract: The work is aimed at studying hygrothermal effects on uncured glass-epoxy fiber prepreg (F-161 -Hexcel Co.) using luminescence spectroscopy under steady-state conditions. The fluorescence extrinsic method was employed using the 9-anthroic acid probe, whose photophys...

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Hygroscopic Behavior of Woven Fabric Carbon-Epoxy Composites

Cited by 47 publications

References 26 publications

A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli

A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli

Photocurable Organic Gate Insulator for the Fabrication of High‐Field Effect Mobility Organic Transistors by Low Temperature and Solution Processing

Efeito higrotérmico em prepregs de fibra de vidro/epóxi por espectroscopia de luminescência

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