Environmental Effects on Epoxy Matrix Composites

Springer, G. S.

doi:10.1520/stp36915s

Cited by 29 publications

(33 citation statements)

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“…These results are consistent with those observed with graphite-epoxy composites [2,3,4]. However, for the polyester-E glass composites tested here the apparent diffusivity also depends on the relative humidity, while for graphite-epoxy composites the diffusivity was not affected significantly by the relative humidity.…”

Section: Resultssupporting

confidence: 92%

Moisture Absorption of Polyester-E Glass Composites

Loos

Springer

Sanders

et al. 1980

Journal of Composite Materials

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Moisture absorption of polyester-E glass composites immersed in liquids and in humid air were investigated. The weights of the composites as a function of exposure time and temperature were measured for three different types of materials. Tests were performed a) with the materials immersed in distilled water, in saturated salt water, in No. 2 diesel fuel, in jet A fuel, in synthetic aviation lubricant, in gasoline, and b) with the materials exposed to humid air. The apparent maximum moisture contents and the apparent diffusivities were deduced from the data.

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Section: Resultssupporting

confidence: 92%

Moisture Absorption of Polyester-E Glass Composites

Loos

Springer

Sanders

et al. 1980

Journal of Composite Materials

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“…5, the hydrolytic damage rate seems to follow this order: APMES < APDES < APTES. This result is in accordance with other results regarding hydrolysis rates of the same silane-coupling coatings (27), in which it was concluded that the hydrolysis rate of the glass-silane siloxane linkages, Si (glass) -O-Si (silane) , is greater than that of silane-silane linkages, Si (silane) -O-Si (silane) .…”

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confidence: 92%

Effect of Glass Fiber Surface Treatments on Mechanical Strength of Epoxy Based Composite Materials

Iglesias

González‐Benito

Aznar

et al. 2002

Journal of Colloid and Interface Science

108

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Sizing glass fibers with silane coupling agents enhances the ad-hesion and the durability of the fiber/polymer matrix interface in composite materials. There are several tests to determine the inter-facial strength between a fiber and resin, but all of them present difficulties in interpreting the results and/or sample preparation. In this study, we observed the influence of different aminosilanes fiber coatings on the resistance of epoxy-based composite materials using a very easy fractographic test. In addition, we tried a new flu-orescence method to get information on a molecular level precisely at the interface. Strength was taken into account from two stand-points: (i) mechanical strength and (ii) the resistance to hydrolysis of the interface in oriented glass-reinforced epoxy-based composi-tes. Three silanes: γ -aminopropyltriethoxysilane, γ -Aminopropyl-methyldiethoxysilane, and γ -Aminopropyldimethylethoxysilane were used to obtain different molecular structures at the interface. It was concluded that: (i) the more accessible amine groups are, the higher the interface rigidity is; (ii) an interpenetrating network mechanism seems to be the most important for adhesion and there-fore to the interfacial strength; and (iii) the higher the degree of crosslinking in the silane coupling layer is, the higher the hydrolytic damage rate is.

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“…Models of moisture (and oxygen) diffusion based on Fick's law have been widely used to describe the process [17]. …”

Section: Moisture Diffusionmentioning

confidence: 99%

Accelerated Tests of Environmental Degradation in Composite Materials

Reynolds

McManus

2001

Composite Structures: Theory and Practice

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High temperature polymer matrix composites are key candidates for the structural components of proposed supersonic transport aircraft. The operational environment of these vehicles exposes the airframe to harsh conditions, including temperature extremes and moisture. These environments have been seen to cause visible damage in polymer matrix composites in timescales much less than the lifetime of the vehicle. Therefore, there is an urgent requirement for accelerated testing of the key components of the environment. A first step to this goal is to identify the components of the environment responsible for the damage. The effects of a realistic moisture and thermal environment on two high temperature polymer matrix composites (PETI-5 and PIXA-M) have been investigated in this work. An extensive test program was developed to test the response of the materials to this baseline environment and its individual components: time at moisture, moisture cycling, time at temperature and thermal cycling. Mechanism-based models were used to design accelerated moisture cycles and acceler ed thermal cycles in an attempt to speed up the response to these environmental factors. These accelerated cycles were also used in the test program. The results showed visible damage in the form of cracking in both r.terials.The PIXA-M material was found to show more damage than the PETI-5. Cracking was confined to a thin layer of material next to the exposed edge. This suggests that the environmental exposure is reducing the effective fracture toughness of the material in this layer more than in the interior. Analysis suggests that this layer is exposed to more of the environmental components and fluctuations than the material in the interior. The individual components of time at moisture and thermal cycling were seen to cause cracking, while time at temperature did not, and moisture cycling did not appear to accelerate moisture damage. The combined environments in the baseline cycle caused more damage than any one component of the cycle on its own. Evidence points to the combined effects of time at moisture and thermal cycling as being the dominant parameters causing damage, while moisture cycling controls the extent of the damaged region. Although the designed accelerated cycles were not successful in accelerating the damage from the baseline cycle, they were instrumental in establishing what were the dominant parameters. It is suggested that a promising way of accelerating the damage observed under the realistic conditions is by combining an isomoisture environment with a cyclical stress environment, which can be achieved either thermally or mechanically.Thesis Supervisor:

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Environmental Effects on Epoxy Matrix Composites

Cited by 29 publications

References 0 publications

Moisture Absorption of Polyester-E Glass Composites

Moisture Absorption of Polyester-E Glass Composites

Effect of Glass Fiber Surface Treatments on Mechanical Strength of Epoxy Based Composite Materials

Accelerated Tests of Environmental Degradation in Composite Materials

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