The Experts below are selected from a list of 6 Experts worldwide ranked by ideXlab platform
J Verdu - One of the best experts on this subject based on the ideXlab platform.
-
interaction between cracking and oxidation in organic matrix composites
Journal of Composite Materials, 2005Co-Authors: X Colin, A Mavel, C Marais, J VerduAbstract:The thermal oxidative degradation of carbon fiber/bismaleimide (Hexel T800H/F655-2) and carbon fiber/amine-cross-linked epoxy (Cytec Fiberite IM7/977-2) unidirectional composites and their corresponding neat polymers has been studied in air at temperatures ranging from 150 to 240 C by optical microscopy, using an interferential contrast, and IR microspectrophotometry.A coarse analysis of the damaged zone allowed the determination of main kinetic characteristics in the whole degradation process (oxidation, crack propagation, and their interaction) for each principal direction of the composite materials.It has been found that cracks initiate at the sample free surfaces when a critical value of embrittlement is reached in the oxidized layer. Then, cracks propagate differently toward the core according to both the fiber orientation and the nature of the composite system. The difference in behavior between T800H/F655-2 and IM7/977-2 systems can be explained by a difference in polymer toughness and oxygen perme...
Wendy Tian - One of the best experts on this subject based on the ideXlab platform.
-
accelerated ageing versus realistic ageing in aerospace composite materials iii the chemistry of thermal ageing in bismaleimide based composites
Journal of Applied Polymer Science, 2007Co-Authors: B Dao, J Krstina, J. Mardel, J H Hodgkin, Wendy TianAbstract:Samples of two Aerospace grade bismaleimide composites (Cytec Fiberite 5250-4/IM7 and 5250-4/RTM) were subject to long-term (≈ 1-year) thermal ageing in air at temperatures of 70, 120, 170, 200, and 250°C. The changes to the chemical and physicochemical structure of the composite were then analyzed by a range of different techniques, including gravimetric analysis, Fourier Transform infrared spectroscopy, and dynamic mechanical analysis, to compare the effects of the different ageing temperatures and to see if much simpler and more fundamental testing techniques could provide more informative forecasting information than the standard mechanical testing methods. The results emphasize the strong variation in chemistry that takes place between the surface and the interior of the composite materials at all temperatures tested. The results also confirmed the significant variations in chemical and physicochemical ageing mechanisms (e.g. glass transition temperature, Tg) that occur between the more realistic ageing temperatures encountered “in service” (∼ 120°C) and the accelerated ageing conditions often used for ageing studies (>170°C). This article highlights the lack of agreement in scientific literature on the basic chemistry of bismaleimide cure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
X Colin - One of the best experts on this subject based on the ideXlab platform.
-
interaction between cracking and oxidation in organic matrix composites
Journal of Composite Materials, 2005Co-Authors: X Colin, A Mavel, C Marais, J VerduAbstract:The thermal oxidative degradation of carbon fiber/bismaleimide (Hexel T800H/F655-2) and carbon fiber/amine-cross-linked epoxy (Cytec Fiberite IM7/977-2) unidirectional composites and their corresponding neat polymers has been studied in air at temperatures ranging from 150 to 240 C by optical microscopy, using an interferential contrast, and IR microspectrophotometry.A coarse analysis of the damaged zone allowed the determination of main kinetic characteristics in the whole degradation process (oxidation, crack propagation, and their interaction) for each principal direction of the composite materials.It has been found that cracks initiate at the sample free surfaces when a critical value of embrittlement is reached in the oxidized layer. Then, cracks propagate differently toward the core according to both the fiber orientation and the nature of the composite system. The difference in behavior between T800H/F655-2 and IM7/977-2 systems can be explained by a difference in polymer toughness and oxygen perme...
B Dao - One of the best experts on this subject based on the ideXlab platform.
-
accelerated ageing versus realistic ageing in aerospace composite materials iii the chemistry of thermal ageing in bismaleimide based composites
Journal of Applied Polymer Science, 2007Co-Authors: B Dao, J Krstina, J. Mardel, J H Hodgkin, Wendy TianAbstract:Samples of two Aerospace grade bismaleimide composites (Cytec Fiberite 5250-4/IM7 and 5250-4/RTM) were subject to long-term (≈ 1-year) thermal ageing in air at temperatures of 70, 120, 170, 200, and 250°C. The changes to the chemical and physicochemical structure of the composite were then analyzed by a range of different techniques, including gravimetric analysis, Fourier Transform infrared spectroscopy, and dynamic mechanical analysis, to compare the effects of the different ageing temperatures and to see if much simpler and more fundamental testing techniques could provide more informative forecasting information than the standard mechanical testing methods. The results emphasize the strong variation in chemistry that takes place between the surface and the interior of the composite materials at all temperatures tested. The results also confirmed the significant variations in chemical and physicochemical ageing mechanisms (e.g. glass transition temperature, Tg) that occur between the more realistic ageing temperatures encountered “in service” (∼ 120°C) and the accelerated ageing conditions often used for ageing studies (>170°C). This article highlights the lack of agreement in scientific literature on the basic chemistry of bismaleimide cure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
A Mavel - One of the best experts on this subject based on the ideXlab platform.
-
interaction between cracking and oxidation in organic matrix composites
Journal of Composite Materials, 2005Co-Authors: X Colin, A Mavel, C Marais, J VerduAbstract:The thermal oxidative degradation of carbon fiber/bismaleimide (Hexel T800H/F655-2) and carbon fiber/amine-cross-linked epoxy (Cytec Fiberite IM7/977-2) unidirectional composites and their corresponding neat polymers has been studied in air at temperatures ranging from 150 to 240 C by optical microscopy, using an interferential contrast, and IR microspectrophotometry.A coarse analysis of the damaged zone allowed the determination of main kinetic characteristics in the whole degradation process (oxidation, crack propagation, and their interaction) for each principal direction of the composite materials.It has been found that cracks initiate at the sample free surfaces when a critical value of embrittlement is reached in the oxidized layer. Then, cracks propagate differently toward the core according to both the fiber orientation and the nature of the composite system. The difference in behavior between T800H/F655-2 and IM7/977-2 systems can be explained by a difference in polymer toughness and oxygen perme...
