Impact of Prolonged Exposure of Eleven Years to Hot Seawater on the Degradation of a Thermoset Composite

Abstract

This paper presents a long-term experimental investigation of E-glass/epoxy composites’ durability exposed to seawater at different temperatures. The thermoset composite samples were exposed to 23 °C, 45 °C and 65 °C seawater for a prolonged exposure time of 11 years. The mechanical performance as a function of exposure time was evaluated and a strength-based technique was used to assess the durability of the composites. The experimental results revealed that the tensile strength of E-glass/epoxy composite was reduced by 8.2%, 29.7%, and 54.4% after immersion in seawater for 11 years at 23 °C, 45 °C, and 65 °C, respectively. The prolonged immersion in seawater resulted in the plasticization and swelling in the composite. This accelerated the rate of debonding between the fibers and matrix. The failure analysis was conducted to investigate the failure mode of the samples. SEM micrographs illustrated a correlation between the fiber/matrix debonding, potholing, fiber pull-out, river line marks and matrix cracking with deterioration in the tensile characteristics of the thermoset composite.

A rational study on the hydrothermal aging of AFP manufactured CF/polyetherketoneketone composites with in situ consolidation supported by acoustic emission inspection

“…The weakened interface reduces the adhesion between the matrix and fibers, thereby promoting the occurrence of fiber pull‐out at lower tensile loads and the formation of multiple micro‐voids. In essence, the fiber‐matrix debonding can take place through the breakage of chemical bonding due to the weakening of the fiber‐matrix interface bonding due to swelling of the resin owing to the absorbed water, as an also similar conclusion drawn in literature 36 . The fractured surface of the AA composite given in Figure 8b (left) shows comparatively higher amount of fragmented debris than that of BA one, which can be attributed to the fact that the hydrothermal aging process makes CF/PEKK composites brittle and hence lead to its failure at lower strain state.…”

“…Note that the increase in aging time accelerates the water absorption and degradation process in polymers, specifically at the initial stages of the aging process. However, water may also hinder the motion of the polymer segments, thus making the polymer matrix more brittle 36 and in turn results in lower tensile strain values at failure after the aging. The decrease in the tensile stress and strain at failure, which is conspicuously higher than the one in tensile modulus, is also intuitively expected.…”

“…Based on Silhouette criteria, three clusters are formed as a result of the classification of the AE data and each of the cluster corresponds to a distinctive damage type. AE data obtained from tensile tests for carbon fiber reinforced polymer composites in the peak frequency ranges of 0-300, 200-400, and 400-550 kHz are usually associated with matrix damage, delamination or interface failure and fiber related failure (i.e., fiber pull-out and breakage), in the given order 35,36 while being informed that these frequency ranges may show variability in literature. It can be seen from Figure 7a,b, three peak frequency ranges are associated with three different damage types.…”

Effect of Processing Techniques on the Microstructure and Mechanical Performance of High-Density Polyethylene

“…A crosshead speed of 25 mm/min was chosen for reasons explained in the following sections. Mechanical properties such as yield strength, fracture stress, modulus, and strain at break were obtained from the stress–strain curves [ 10 , 34 , 35 , 36 , 37 , 38 ]. These results were obtained by averaging at least five specimens with a standard deviation of less than 5%.…”

Thermal Aging Effects on the Mechanical Behavior of Glass-Fiber-Reinforced Polyphenylene Sulfide Composites

“…However, the mechanical properties of the GF/PPS composites can be further improved. The mechanical properties of composite materials reinforced with fibers depend strongly on the characteristics of the fibers and matrix, the bond efficiency, and the interaction between them [ 21 , 22 ]. Several studies have been performed to investigate the physical properties and mechanical behavior of fiber-reinforced PPS [ 23 , 24 , 25 , 26 , 27 , 28 ].…”