Mechanical characterization of different epoxy resins enhanced with carbon nanofibers

Santos, P.; Maceiras, Alberto; Valvez, Sara; Reis, P.N.B.

doi:10.3221/igf-esis.55.15

Cited by 11 publications

(14 citation statements)

References 46 publications

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“…Finally, as expected, the bending strain decreases with increasing filler content for both resins. These results are in good agreement with those obtained by Santos et al [37], for whom the same values for the respective resins enhanced with CNFs were found. In this case, the maximum bending strength was also achieved for the same weight contents shown in Figure 6, evidence that maximizing the bending properties of the resins also maximizes the bending properties of the laminates produced with them.…”

Section: Resultssupporting

confidence: 93%

“…After curing, the thickness ( t ) obtained for each laminate was 1.5 ± 0.1 mm for laminates with Sicomin resin and 1.9 ± 0.1 for the Ebalta resin. The main mechanical and physical properties of the epoxy resins are summarized in Table 1 , and more details about them can be found in [ 37 ]. The systems were placed inside a vacuum bag and subjected to a load of 2.5 kN to obtain a constant fiber volume fraction and uniform laminate thickness.…”

Section: Methodsmentioning

confidence: 99%

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Effect of Carbon Nanofibers on the Strain Rate and Interlaminar Shear Strength of Carbon/Epoxy Composites

2023

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The static bending properties, different strain rates and interlaminar shear strength (ILSS) of carbon-fiber-reinforced polymers (CFRP) with two epoxy resins nano-enhanced with carbon nanofibers (CNFs) are studied. The effect on ILSS behavior from aggressive environments, such as hydrochloric acid (HCl), sodium hydroxide (NaOH), water and temperature, are also analyzed. The laminates with Sicomin resin and 0.75 wt.% CNFs and with Ebalta resin with 0.5 wt.% CNFs show significant improvements in terms of bending stress and bending stiffness, up to 10%. The values of ILLS increase for higher values of strain rate, and in both resins, the nano-enhanced laminates with CNFs show better results to strain-rate sensitivity. A linear relationship between the logarithm of the strain rate was determined to predict the bending stress, bending stiffness, bending strain and ILSS for all laminates. The aggressive solutions significantly affect the ILSS, and their effects are strongly dependent on the concentration. Nevertheless, the alkaline solution promotes higher decreases in ILSS and the addition of CNFs is not beneficial. Regardless of the immersion in water or exposure to high temperatures a decrease in ILSS is observed, but, in this case, CNF content reduces the degradation of the laminates.

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Section: Resultssupporting

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Effect of Carbon Nanofibers on the Strain Rate and Interlaminar Shear Strength of Carbon/Epoxy Composites

2023

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“…Several contents by weight were studied (0.25, 0.5, 0.75, and 1 wt.%). More details about the resins and CNFs can be found in [ 3 ]. For example, for Sicomin resin with 0.75 wt.% CNFs, 150 g of resin, 33 g of hardener, and 1.37 g of CNFs were used.…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

“…Epoxy resins, in addition to playing the important role of matrix in composite materials, are an important class of thermosetting polymers due to their excellent mechanical properties, high adhesiveness to many substrates, and good thermal and chemical resistances [ 1 , 2 , 3 ].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Carbon Nanofibers on the Viscoelastic Response of Epoxy Resins

2023

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Two epoxy resins with different viscosities were enhanced up to 1 wt.%, applying a simple method with carbon nanofibers (CNFs). These were characterized in terms of static bending stress, stress relaxation, and creep tests. In bending, the contents of 0.5 wt.% and 0.75 wt.% of CNFs on Ebalta and Sicomin epoxies, respectively, promote higher relative bending stress (above 11.5% for both) and elastic modulus (13.1% for Sicomin and 16.2% for Ebalta). This highest bending stress and modulus occurs for the lower viscosity resin (Ebalta) due to its interfacial strength and dispersibility of the fillers. Creep behaviour and stress relaxation for three stress levels (20, 50, and 80 MPa) show the benefits obtained with the addition of CNFs, which act as a network that contributes to the immobility of the polymer chains. A long-term experiment of up to 100 h was successfully applied to fit the Kohlrausch–Williams–Watts (KWW) and Findley models to stress relaxation and creep behaviour with very good accuracy.

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Thermal, mechanical and electrical performance of structural epoxy resins filled with carbon nanofibers

Guadagno,

Naddeo,

Raimondo

2023

J Therm Anal Calorim

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Carbon nanofibers (CNFs) were heat-treated at 1100 °C (CNF1100) and 2500 °C (CNF2500), respectively, and embedded as fillers at different mass percentages into an epoxy mixture. The paper aims at evaluating, through a comparison between the two different types of resulting nanocomposites, the influence of the CNF heat treatment on the thermal, mechanical, and electrical performance of the formulated samples. Thermogravimetric analysis (TGA) showed oxidative stability in the air of CNF2500 approximately 200 °C higher than the CNF1100 ones. The first oxidation stage of the resins embedding the two typologies of CNFs falls between 380 and 480 °C. This means that the temperature of the heat treatment of the nanofiller does not influence the temperature at which the thermodegradation of the nanocomposites starts. Differential Scanning Calorimetry (DSC) data show that the highest degree of cure (DC) was recorded for the epoxy samples filled with CNF2500. CNF thermal treatment increases the direct current (dc) conductivity of the nanocomposite by 3 orders of magnitude around the electrical percolation threshold (EPT) and increases the storage modulus of the CNF2500-based resins up to 60 °C compared with the unfilled resin. The peculiar wall structure of CNF1100 determines a further slight enhancement. Tunneling Atomic Force Microscopy (TUNA) reveals that the CNFs are evenly distributed on the nanodomains showing higher electric current values for samples loaded with CNF2500.

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Mechanical characterization of different epoxy resins enhanced with carbon nanofibers

Cited by 11 publications

References 46 publications

Effect of Carbon Nanofibers on the Strain Rate and Interlaminar Shear Strength of Carbon/Epoxy Composites

Effect of Carbon Nanofibers on the Strain Rate and Interlaminar Shear Strength of Carbon/Epoxy Composites

Effect of Carbon Nanofibers on the Viscoelastic Response of Epoxy Resins

Thermal, mechanical and electrical performance of structural epoxy resins filled with carbon nanofibers

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