Carbon nanotube-reinforced glass fiber epoxy composite laminates exposed to hygrothermal conditioning

Abstract

Glass fiber-reinforced polymer composites (GFRP) were prepared and reinforced with two types of multiwalled carbon nanotubes, i.e., amino-functionalized (ACNT) and pristine nanotubes (PCNT). Incorporation of ACNT leads to a significant decrease in equilibrium water content and diffusion coefficient vis-à-vis GFRP composites when immersed in seawater (SW) and distilled water (DW). The experimental results illustrate that the material degradation of the composites is significantly more on immersion in SW as compared to DW. Interestingly, a decrease in mechanical properties was observed initially; however, at a later stage the trend reversed and a recovery in the mechanical properties was seen. This recovery in mechanical properties is ascribed to the possible secondary crosslinking network between excess sodium ions in seawater with the hydroxyl groups of cured epoxy and also to the unreacted silanols on the glass fiber surface. On the contrary, PCNT composites revealed a continuous decreasing trend in mechanical behavior versus aging duration. The present study suggests that it may be advantageous and safer to re-condition (for 15-20 days) FRP nanocomposite parts before being installed in naval vessels.

Evaluation of Aging Resistance in UHMWPE/LLDPE Blend‐Based Carbon Nanotubes Nanocomposites

“…The samples aged by immersion in water at 80 °C for 7 days (A 2 ) at also presented a decrease in the impact strength, but to a lesser extent. It was also noticed that the nanocomposites were less sensible to water aging than UHMWPE/LLDPE blends, i.e., they presented higher impact resistance when compared to the blends . Addition of low contents of carbon nanotubes reduces the water absorption capacity of the blends and improves its resistance to hydrothermal aging.…”

“…It was also noticed that the nanocomposites were less sensible to water aging than UHMWPE/LLDPE blends, i.e., they presented higher impact resistance when compared to the blends. [20][21][22][23] Addition of low contents of carbon nanotubes reduces the water absorption capacity of the blends and improves its resistance to hydrothermal aging. Similar results were obtained in epoxy resin filled multi-wall carbon nanotubes [20][21][22] and carbon nanotube/PA6 nanocomposites.…”

“…[20][21][22][23] Addition of low contents of carbon nanotubes reduces the water absorption capacity of the blends and improves its resistance to hydrothermal aging. Similar results were obtained in epoxy resin filled multi-wall carbon nanotubes [20][21][22] and carbon nanotube/PA6 nanocomposites. [23] There was a slight decrease in the degree of crystallinity, and no plasticizer behavior was identified due to the hydrophobic nature of the polymer material used (Figure 4).…”

Enhanced durability of carbon nanotube grafted hierarchical ceramic microfiber-reinforced epoxy composites

“…The conclusions of the majority of early studies on dispersed CNT systems differ depending on the CNT functionalization, CNT volume fractions, dispersion methodology and the CNT/polymer interactions. Some of the prominent studies on durability of these systems are summarized in references [43] - [47]. …”

“…While there are several studies on the long-term effects of water and temperature on resin chemistry and mechanical property changes in dispersed CNT-epoxy and CNT-FRP systems [43] - [47], there are no studies on the durability of hierarchical composites, where the CNTs are directly attached to fiber surfaces. The current study focuses on measuring the aging characteristics (water diffusivity, polymer plasticization and hydrolysis reactions) of the nanoscale CNT reinforcement of the polymer in a model aluminoborosilicate fiber composite system.…”