Influence of moisture on the thermal and mechanical properties of autoclaved and oven-cured Kevlar-49/epoxy laminates

Akay, M.; Mun, Seung‐Hyun; Stanley, A. Joseph

doi:10.1016/s0266-3538(97)00017-1

Cited by 112 publications

(52 citation statements)

References 16 publications

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“…Like with others before us [11], not such exactitude is adopted here nor any corrections introduced to the collected data, since our actual scope is not recording absolute diffusivity values to extreme accuracy but monitoring diffusivity changes induced by interfacial affinity variation. For this, we deem sufficient to carry identical absorption experiments under specified conditions on specimens of a given constant geometry but variable fiber surface treatment, followed by effective diffusivity data comparisons with the results obtained through identical procedures in benchmark cases, like that on a pure matrix specimen or on a ''perfectly'' bonded interface.…”

Section: Moisture Absorption Testsmentioning

confidence: 99%

Evaluation of interfacial relaxation due to water absorption in fiber–polymer composites

Tsenoglou

Pavlidou

Papaspyrides

2006

Composites Science and Technology

168

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Section: Moisture Absorption Testsmentioning

confidence: 99%

Evaluation of interfacial relaxation due to water absorption in fiber–polymer composites

Tsenoglou

Pavlidou

Papaspyrides

2006

Composites Science and Technology

168

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“…Techniques for tracking moisture distribution through a laminate with a nuclear probe were demonstrated by Whiteside et al [15] using labeled hydrogen atoms (in heavy water, D 2 0). Effects of the composite manufacturing techniques [16] were shown to have a significant effect on moisture uptake. Oven cured composites were shown to have more voids than those autoclave cured, leading to greater moisture absorption/diffusivity and a concomitant reduction in glass transition temperature and properties.…”

Section: Behavior Of Pmcs Exposed To Moisture Environmentsmentioning

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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“…Indeed, water can penetrate into the composites by three main mechanisms: diffusion of the water through the matrix, capillary along fiber-matrix interface and percolating flow and storage of water in micro-cracks [8]. These diffusion mechanisms generally lead to the following damages in the composites: degradation by a hydrolysis reaction of unsaturated groups within the resin [9,10], interfacial fracture [11][12][13][14], debonding [15] and interlaminar toughness [16][17][18][19][20]. Beyond these considerations, it is well known that water absorption also affects the mechanical behavior of composite materials globally [21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Effect of Fatigue Testing and Aquatic Environment on the Tensile Properties of Glass and Kevlar Fibers Reinforced Epoxy Composites

Menail¹,

Mahi²

2015

J Aeronaut Aerospace Eng

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This paper presents the experimental results of the influence of water ageing after mechanical fatigue on glassfiber composites, compared with Kevlar-fiber composites. The tested specimens were subjected to fatigue during various numbers of cycles (100 to 50000). After that, they were immersed into tap water and simulated seawater for different periods (4, 20 and 40 days). Next, the tensile tests were made on the unaged and aged samples in order to determine the evolution of the strength and stiffness under local interactions of the water absorption and fatigue. The obtained results showed that tensile characteristics were clearly affected by the immersion treatment and fatigue loading. In fact, the residual stiffness and residual strength decreased when the immersion time and cycle number of fatigue increased, indicating that the studied composites have experienced some forms of mechanical damage.

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Influence of moisture on the thermal and mechanical properties of autoclaved and oven-cured Kevlar-49/epoxy laminates

Cited by 112 publications

References 16 publications

Evaluation of interfacial relaxation due to water absorption in fiber–polymer composites

Evaluation of interfacial relaxation due to water absorption in fiber–polymer composites

Accelerated Tests of Environmental Degradation in Composite Materials

Effect of Fatigue Testing and Aquatic Environment on the Tensile Properties of Glass and Kevlar Fibers Reinforced Epoxy Composites

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