Abstract:Abstract. Thermo-oxidative degradation of graphite/epoxy composite laminates due to exposure to elevated temperatures was characterized using weight loss and short beam strength (SBS) reduction data. Test specimens obtained from 24-ply, unidirectional AS4/3501-6 graphite/epoxy laminates were subjected to 100, 150, 175, and 200°C for 5000 hours (208 days) in air. Predictive differential models for the weight loss and short beam strength reduction were developed using the isothermal degradation data only up to 2… Show more
“…The weight loss rises sharply during the initial 100 h of aging. This may be attributed to desorption of the residual moisture and volatiles and is not related to polymer degradation [27,87]. A faster weight loss rate is evident over the 400 to 600 h range.…”
Section: Weight Loss Measurementsmentioning
confidence: 90%
“…Thermal-oxidative aging may irreversibly change the chemical structure of polymer matrix composites [13,14]. Alterations to the chemical structure during thermooxidative [1,9,13,[15][16][17][18][19][20][21][22], loss of volatiles [2,[23][24][25][26][27], dehydration [13,28,29], chain scission [25,[30][31][32][33][34], additional cross-linking [1,13], and carbonyl growth [19,29]. The initial chemical changes are accompanied by dehydration of secondary alcohols and the release of low molecular weight gaseous species due to random chain scission.…”
Thin-skinned organic matrix composites within aeronautical structures are subjected to thermooxidative aging during their service life, leading to reductions in their durability. In this paper, a durability evaluation of fiberglass epoxy prepreg is performed on the original composite thickness before and after 800 h isothermal aging at 82°C. The characterization of both aged and unaged composites comprised tensile tests, DMA, FTIR, weight loss measurements, SEM, and DSC. The tensile strength and modulus of the composites increased after being exposed to pronounced aging conditions, whereas a decrease was observed in the toughness. DMA results revealed that the glass transition temperature and rubbery state modulus increased as a result of the thermooxidative aging. FTIR spectroscopy demonstrated the formation of carbonyl compounds due to oxidation of the chemical structure of the resin. SEM observations indicated the existence of minor superficial cracking and poor fiber-matrix adhesion after aging. In addition, a minor mass change was observed from mass loss monitoring methods. The overall findings suggest that postcuring and physical aging enhanced the brittleness of the resin, leading to a significant decline in the useful structural life of the thin-skinned composite.
“…The weight loss rises sharply during the initial 100 h of aging. This may be attributed to desorption of the residual moisture and volatiles and is not related to polymer degradation [27,87]. A faster weight loss rate is evident over the 400 to 600 h range.…”
Section: Weight Loss Measurementsmentioning
confidence: 90%
“…Thermal-oxidative aging may irreversibly change the chemical structure of polymer matrix composites [13,14]. Alterations to the chemical structure during thermooxidative [1,9,13,[15][16][17][18][19][20][21][22], loss of volatiles [2,[23][24][25][26][27], dehydration [13,28,29], chain scission [25,[30][31][32][33][34], additional cross-linking [1,13], and carbonyl growth [19,29]. The initial chemical changes are accompanied by dehydration of secondary alcohols and the release of low molecular weight gaseous species due to random chain scission.…”
Thin-skinned organic matrix composites within aeronautical structures are subjected to thermooxidative aging during their service life, leading to reductions in their durability. In this paper, a durability evaluation of fiberglass epoxy prepreg is performed on the original composite thickness before and after 800 h isothermal aging at 82°C. The characterization of both aged and unaged composites comprised tensile tests, DMA, FTIR, weight loss measurements, SEM, and DSC. The tensile strength and modulus of the composites increased after being exposed to pronounced aging conditions, whereas a decrease was observed in the toughness. DMA results revealed that the glass transition temperature and rubbery state modulus increased as a result of the thermooxidative aging. FTIR spectroscopy demonstrated the formation of carbonyl compounds due to oxidation of the chemical structure of the resin. SEM observations indicated the existence of minor superficial cracking and poor fiber-matrix adhesion after aging. In addition, a minor mass change was observed from mass loss monitoring methods. The overall findings suggest that postcuring and physical aging enhanced the brittleness of the resin, leading to a significant decline in the useful structural life of the thin-skinned composite.
“…The initial weight loss may be attributed to the desorption of the residual moisture and volatiles and may not be attributed to polymer degradation. 40 The epoxy composites with –NH 2 and –COOH functionalized MWCNTs showed slightly more mass and thickness changes at longer exposure periods, which appears related to polymer chain scission. The spray-washing used to simulate rain during the aging of epoxy and epoxy-composites may have caused some mass loss, where the wet aging process further oxidized and weakened the surface of the aged samples and led to the loss of microplastic fragments and nanofibers from the samples during aging.…”
Nano-enabled consumer materials could degrade during their use or end-of-life disposal due to weathering. Understanding the potential risks from the release and the toxicity of embedded nanomaterial is needed.
“…A rapid preliminary of weight loss up to 336 h aging on the curves obtained from both neat and nano-filled GE specimens may be attributed to degassing and/or desorption of moisture and volatiles during high-temperature exposure. 21,37 Then, from around 336 h, the mass of the thermally aged GE specimens decreased with a lower rate and gradually moved toward stability. Figure 4.Weight loss rate for (a) FML and, (b) GE specimens versus aging time at 130 ℃.…”
Section: Resultsmentioning
confidence: 99%
“…Ozcelik et al. 21 reported that the thermo-oxidative aging has a significant effect on weight loss and mechanical properties of graphite/epoxy composites. After 5000 h of thermo-oxidative aging at 150 ℃, 175 ℃, and 200 ℃, respectively, 0.81, 2.31, and 5.84% weight loss associated with 10.87, 33.07, and 49.86% short beam strength reduction were observed.…”
One of the main problems of polymer matrix composites in critical applications is their high sensitivity to thermal conditions. Therefore, an experimental study was performed to evaluate the thermal durability of traditional plain weave E-glass/epoxy as well as fiber metal laminates as a possible alternative in this case. In this way, both the laminate types were exposed to thermal aging at 130 ℃ for five weeks, and the plausible degradation is investigated through weight loss analyzes and mechanical testing. The possibility of improving the mechanical behavior of the studied laminates by nanoclay was also studied. The results demonstrated that the weight loss and mechanical degradation were more pronounced in thermally aged plain weave E-glass/epoxy composites. The results also indicated that nanoclay could enhance the mechanical properties of both laminates. On the basis of the results, the shielding role of aluminum layers and thermal resistance of nanoclay can synergistically offer a novel class of nano-fiber metal laminates with high thermal tolerance in thermo-oxidative conditions.
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