The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
F.y.c. Boey - One of the best experts on this subject based on the ideXlab platform.
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Humidity and Autoclave Pressure effect on the interfacial shear strength of a microwave cured epoxy-glass fibre composite
Polymer Testing, 1995Co-Authors: F.y.c. BoeyAbstract:Abstract Microwave radiation curing of thermoset composite has been shown to achieve higher strengths and stiffness than conventional thermal curing, due to a higher Interfacial Shear Strength (ISS). Industrial processing of critical composite components requires the application of additional Pressure to reduce the final composite void content. The nucleation and growth of voids is dominantly driven by vaporisation of moisture content, which is particularly accelerated in the microwave process, due to the high dielectric constant of water. This paper examines the effect of humidity content and Pressure on the Interfacial Shear Strength of a hot curing epoxy/fibre glass composite that was microwave cured. Results indicate that the ISS decreased with higher humidity % for different microwave power settings from 500–75 W. Application of a 8 bar Pressure during cure increased the ISS values for all humidity levels significantly. This was attributed to the reduction in the interfacial voids, so that the effective interface between the fibre and matrix is increased.
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Void reduction in Autoclave processing of thermoset composites
Composites, 1992Co-Authors: F.y.c. Boey, S.w. LyeAbstract:Abstract Industrial production of thermoset composite components usually involves the application of a vacuum bagging and Autoclave Pressure to minimize void percentage, usually to less than 5%. The application of vacuum bagging can be time consuming, with the actual vacuum application limited to a short interval during the curing process to avoid resin starvation. At the maximum vacuum achievable void reduction is only to about 10%, with a higher applied vacuum resulting in larger void diameters. This paper reports on the use of high Pressure of up to 7000 kPa by means of an isostatic press, without vacuum application, to effectively reduce the void levels to below 3%. Void reduction occurred only above an initial pressurization level, at about 400 kPa, after which significant reduction was obtained until about 5000 kPa. Further pressurization reduced the void content only marginally.
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Void reduction in Autoclave processing of thermoset composites: Part 2: Void reduction in a microwave curing process
Composites, 1992Co-Authors: F.y.c. Boey, S.w. LyeAbstract:Abstract Microwave curing of thermoset composites has been experimentally shown to be both feasible and viable. There are, however, additional problems when the process is applied industrially such as maximization of the glass transition temperature and reduction of the void content. This paper attempts to explain how the reduction of void content can be achieved in microwave curing, by means of a modified approach involving vacuum bagging and applied Autoclave Pressure.
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High-Pressure microwave curing process for an epoxy-matrix/glass-fibre composite
Journal of Materials Processing Technology, 1992Co-Authors: F.y.c. Boey, I. Gosling, S.w. LyeAbstract:Abstract The two main process parameters affecting the final mechanical properties of thermoset composites are the cure cycle and the reduction in void content. To effect the former, a conventional thermal process is used normally, with the cycle duration lasting a matter of hours. Recent work by the authors has indicated that this can be significantly shorter by using a microwave curing process. In order to apply the same microwave process industrially, reduction in void content must be accomplished. The conventional industrial practice is to use both a vacuum bagging application and an applied Autoclave Pressure. This paper describes how reduction in void content can be achieved for a microwave process by means of a high-Pressure process that avoids the usage of a continued vacuum evacuation.
S.w. Lye - One of the best experts on this subject based on the ideXlab platform.
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Void reduction in Autoclave processing of thermoset composites
Composites, 1992Co-Authors: F.y.c. Boey, S.w. LyeAbstract:Abstract Industrial production of thermoset composite components usually involves the application of a vacuum bagging and Autoclave Pressure to minimize void percentage, usually to less than 5%. The application of vacuum bagging can be time consuming, with the actual vacuum application limited to a short interval during the curing process to avoid resin starvation. At the maximum vacuum achievable void reduction is only to about 10%, with a higher applied vacuum resulting in larger void diameters. This paper reports on the use of high Pressure of up to 7000 kPa by means of an isostatic press, without vacuum application, to effectively reduce the void levels to below 3%. Void reduction occurred only above an initial pressurization level, at about 400 kPa, after which significant reduction was obtained until about 5000 kPa. Further pressurization reduced the void content only marginally.
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Void reduction in Autoclave processing of thermoset composites: Part 2: Void reduction in a microwave curing process
Composites, 1992Co-Authors: F.y.c. Boey, S.w. LyeAbstract:Abstract Microwave curing of thermoset composites has been experimentally shown to be both feasible and viable. There are, however, additional problems when the process is applied industrially such as maximization of the glass transition temperature and reduction of the void content. This paper attempts to explain how the reduction of void content can be achieved in microwave curing, by means of a modified approach involving vacuum bagging and applied Autoclave Pressure.
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High-Pressure microwave curing process for an epoxy-matrix/glass-fibre composite
Journal of Materials Processing Technology, 1992Co-Authors: F.y.c. Boey, I. Gosling, S.w. LyeAbstract:Abstract The two main process parameters affecting the final mechanical properties of thermoset composites are the cure cycle and the reduction in void content. To effect the former, a conventional thermal process is used normally, with the cycle duration lasting a matter of hours. Recent work by the authors has indicated that this can be significantly shorter by using a microwave curing process. In order to apply the same microwave process industrially, reduction in void content must be accomplished. The conventional industrial practice is to use both a vacuum bagging application and an applied Autoclave Pressure. This paper describes how reduction in void content can be achieved for a microwave process by means of a high-Pressure process that avoids the usage of a continued vacuum evacuation.
Henri Delmas - One of the best experts on this subject based on the ideXlab platform.
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ultrasound in gas liquid systems effects on solubility and mass transfer
Ultrasonics Sonochemistry, 2008Co-Authors: Frederic Laugier, Caroline Andriantsiferana, A M Wilhelm, Henri DelmasAbstract:Abstract The effect of ultrasound on the pseudo-solubility of nitrogen in water and on gas–liquid mass transfer kinetics has been investigated in an Autoclave reactor equipped with a gas induced impeller. In order to use organic liquids and to investigate the effect of Pressure, gas–liquid mass transfer coefficient was calculated from the evolution of Autoclave Pressure during gas absorption to avoid any side-effects of ultrasound on the concentrations measurements. Ultrasound effect on the apparent solubility is very low (below 12%). Conversely ultrasound greatly improves gas–liquid mass transfer, especially below gas induction speed, this improvement being boosted by Pressure. In typical conditions of organic synthesis: 323 K, 1100 rpm, 10 bar, kL · a is multiplied by 11 with ultrasound (20 kHz/62.6 W). The impact of sonication is much higher on gassing out than on gassing in. In the same conditions, this enhancement is at least five times higher for degassing.
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Ultrasound in gas–liquid systems: Effects on solubility and mass transfer
Ultrasonics sonochemistry, 2008Co-Authors: Frederic Laugier, Caroline Andriantsiferana, A M Wilhelm, Henri DelmasAbstract:The effect of ultrasound on the pseudo-solubility of nitrogen in water and on gas-liquid mass transfer kinetics has been investigated in an Autoclave reactor equipped with a gas induced impeller. In order to use organic liquids and to investigate the effect of Pressure, gas-liquid mass transfer coefficient was calculated from the evolution of Autoclave Pressure during gas absorption to avoid any side-effects of ultrasound on the concentrations measurements. Ultrasound effect on the apparent solubility is very low (below 12%). Conversely ultrasound greatly improves gas-liquid mass transfer, especially below gas induction speed, this improvement being boosted by Pressure. In typical conditions of organic synthesis: 323 K, 1100 rpm, 10 bar, k(L).a is multiplied by 11 with ultrasound (20 kHz/62.6 W). The impact of sonication is much higher on gassing out than on gassing in. In the same conditions, this enhancement is at least five times higher for degassing.
Sang Yoon Park - One of the best experts on this subject based on the ideXlab platform.
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Effects of surface pre-treatment and void content on GLARE laminate process characteristics
Journal of Materials Processing Technology, 2010Co-Authors: Sang Yoon Park, Won Jong Choi, Heung Soap Choi, Hyuk KwonAbstract:In this paper the effects of surface morphology and voids formed in the metal sheet–prepreg interface of GLARE laminates were evaluated. The experiments were carried out with aluminum sheets on which the surface morphology was systematically varied by different roughness levels of surface textures (sanding and nylon-pad abrasion) and chemical etches. The surface morphology of the substrates was characterized with profilometry and the static contact angle technique. Void contents at the metal sheet–prepreg interfaces were determined by scanning electron microscopy. The changes in surface roughness and surface energy effectively enhance the bonding strength of GLARE laminates. Experimental results also indicate that the Autoclave Pressure enhances GLARE interfacial bonding, to a certain extent, with low void content.
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The effects of void contents on the long-term hygrothermal behaviors of glass/epoxy and GLARE laminates
Composite Structures, 2010Co-Authors: Sang Yoon Park, Won Jong Choi, Heung Soap ChoiAbstract:In this paper the effect of voids formed in both the glass/epoxy and GLARE laminates on their long-term hygrothermal behaviors are evaluated. By adopting different Autoclave Pressures during a cure cycle, the specimens with different void contents ranging from 0.5% to 2.0% were obtained for both materials. Two types of hygro and thermal aging tests were then carried out according to water absorption in distilled water and thermal cyclic fatigue up to 1500 cycles, respectively. The resulting behaviors of degradation for both materials due to two types of aging tests were evaluated by the test for interlaminar shear strength which is highly affected by those types of aging. Experimental results indicate that the Autoclave Pressure enhances a certain extent of the GLARE’s interfacial bonding with the low void contents. It therefore leads to an increase in the resistance to the hygro and thermal agings.
Heung Soap Choi - One of the best experts on this subject based on the ideXlab platform.
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Effects of surface pre-treatment and void content on GLARE laminate process characteristics
Journal of Materials Processing Technology, 2010Co-Authors: Sang Yoon Park, Won Jong Choi, Heung Soap Choi, Hyuk KwonAbstract:In this paper the effects of surface morphology and voids formed in the metal sheet–prepreg interface of GLARE laminates were evaluated. The experiments were carried out with aluminum sheets on which the surface morphology was systematically varied by different roughness levels of surface textures (sanding and nylon-pad abrasion) and chemical etches. The surface morphology of the substrates was characterized with profilometry and the static contact angle technique. Void contents at the metal sheet–prepreg interfaces were determined by scanning electron microscopy. The changes in surface roughness and surface energy effectively enhance the bonding strength of GLARE laminates. Experimental results also indicate that the Autoclave Pressure enhances GLARE interfacial bonding, to a certain extent, with low void content.
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The effects of void contents on the long-term hygrothermal behaviors of glass/epoxy and GLARE laminates
Composite Structures, 2010Co-Authors: Sang Yoon Park, Won Jong Choi, Heung Soap ChoiAbstract:In this paper the effect of voids formed in both the glass/epoxy and GLARE laminates on their long-term hygrothermal behaviors are evaluated. By adopting different Autoclave Pressures during a cure cycle, the specimens with different void contents ranging from 0.5% to 2.0% were obtained for both materials. Two types of hygro and thermal aging tests were then carried out according to water absorption in distilled water and thermal cyclic fatigue up to 1500 cycles, respectively. The resulting behaviors of degradation for both materials due to two types of aging tests were evaluated by the test for interlaminar shear strength which is highly affected by those types of aging. Experimental results indicate that the Autoclave Pressure enhances a certain extent of the GLARE’s interfacial bonding with the low void contents. It therefore leads to an increase in the resistance to the hygro and thermal agings.
