Effects of acid, alkaline, and seawater aging on the mechanical and thermomechanical properties of glass fiber/epoxy composites filled with carbon nanofibers

Abstract

Owing to the superior corrosion resistance, fiber-reinforced polymer (FRP) composites are the prime choice of structural materials for various marine and chemical industries, where there is a long-term direct contact of the components takes place with corrosive fluids. In this present work, glass fiber/epoxy (GE) composites have been fabricated with and without carbon nanofibers (CNFs), and aging has been carried out in acidic (pH = 1), seawater (pH = 8.2), and alkaline (pH = 13) solutions for 150 days. The resistance of CNF-filled GE composites toward the corrosive fluids has been evaluated in terms of alteration in the mechanical (flexural), microstructural (fractography analysis by field emission scanning electron microscope), and thermomechanical (dynamic mechanical analysis) behavior of the materials. It is revealed that as the immersion time increases, there is a continuous decrement in flexural strength and modulus, and glass-transition temperature (T g ) of all the materials in all these solutions. Compared to the 1% CNF-filled GE composite, control GE composite showed more degradation in the case of alkaline aging and seawater aging. Maximum reduction (56%) in the strength of GE composite was observed due to 150 days of alkaline aging. However, the control GE composite showed better resistance to the acidic solution than that of CNF-filled GE composite. Possible failure modes, changes in the chemistry of the material due to aging have been studied by fractography analysis.

Effect of AC interference on failure mechanism of zinc-rich epoxy coatings in alkaline environment

“…Therefore, the max phase angle (j max ) locating at f = 10 −2 Hz in logf-j decreased gradually from j max = 47.7°to j max = 23.3°, and moreover, the logf-j curves at t = 13 h and t = 50 h coincided within f = 10 −2 −10°Hz. During the experiment time of t = 50-200 h, the coating resistance and charge transfer resistance decreased slightly, indicating that the reaction process of zinc particles and the diffusion process of corrosion products were basically completed at this time, represented by that the max phase angle at f = 10 5 Hz decreased from j max = 56.3°at t = 1 h to j max = 15.3°at t = 200 h. Furthermore, the phase angle at f = 10 −2 Hz representing the mass diffusion increased from j max = 23.3°to j max = 42.0°, indicating that the Zn-rich coating had lost its physical shielding effect, and Zn(OH) 2 diffused into the solution, leading to the appearance of Warburg diffusion impedance in EIS curves [17,18]. Under this circumstance, the electrochemical reaction process at the interface was dominant.…”

Effect of Nanofillers on the Mechanical Properties of Vinyl Ester Resin Used as a Carbon Fiber Reinforced Polymer Matrix

“…At the same time, it is extremely important that the nanofillers are added in a strictly defined amount and are properly dispersed, because too high a content of nanoparticles and an inadequate mixing method may lead to the formation of aggregates and agglomerates, which in turn leads to the deterioration of mechanical properties [26][27][28]. The use of nanofillers may also lead to the improvement of aging resistances, as reported by the authors of the works [29][30][31].…”

Effect of Graphene Oxide-Boron Nitride-Based Dual Fillers on Mechanical Behavior of Epoxy/Glass Fiber Composites

“…Glass fibers have better thermal stability and dimensional stability that initiates their usage in various technological applications [5,6]. In the last few years, material researchers focus on developing advanced materials to decrease fuel [7][8][9][10] consumption in transport industries [11][12][13]. Hence, incorporation of these fibers in polymer material will confidently improvise the stiffness, flexibility, and strength.…”