•An electrical treatment removes epoxy resin from a unidirectional CFRP laminate.•High voltage in an electrical treatment leads to high separation rate.•Gas generated at the CFRP anode causes the ...resin being peeled off.•Rupture of carbon fibers was observed in our treatment at a high voltage.
Removal of epoxy resin from a unidirectional carbon fiber reinforced plastic (CFRP) laminate was achieved with an electrical treatment. The treatment was carried out using a two-electrode cell with the CFRP laminate as the anode, and the effect of applying a high voltage was investigated to reduce the treatment time. The results showed that a high voltage in the electrical treatment leads to high weight loss of the unidirectional CFRP laminate. In the digital microscope images of the residue obtained from the electrolyte after the treatment, fragments assumed to be resin were observed. The removal mechanism involved an electrochemical reaction; however, no decomposition product related to the resin was detected in the electrolyte after the treatment. The results supposed that the removal mechanism of the electrical treatment involved peeling off the resin by gas generated by water electrolysis.
•Pseudo in-situ observation of resin removal revealed the gas peeling.•The peeling started due to voids caused by oxidation of heated resin spots.•Driving force of the peeling was provided by oxygen ...gas from water electrolysis.•Heat from the electrical conduction damaged the carbon fiber.
To promote recycling of carbon fiber reinforced plastics (CFRPs), we investigated the removal mechanism of resin by electrical treatment at high voltage. Using the pseudo in-situ observations, we found that resin removal was triggered by electrical treatment. Based on the observations and current dependency, the resin was removed by a mechanical approach that employed the oxygen gas generated from water electrolysis, i.e., the gas peeled the resin. Moreover, the cathodic treatment was unable to achieve the resin removal because of the high diffusion of hydrogen gas into the epoxy resin. During anodic treatment, CO, CO2, and oxygen gases were generated from the specimen, and damage to the carbon fiber (CF) was observed on the specimen after treatment for 180 min. The mechanism of the resin removal was governed by the resin peeling off from the CFRP composite, which was triggered by the oxygen gas generated from the water electrolysis. During electrical conduction, the peeling was initiated at the voids that were formed by the oxidation of the locally heated resin spots. At low resin content levels, the CF was subjected to damage due to the electrical conduction, which was accompanied by the application of a high voltage.
Carbon fiber reinforced plastics (CFRP) are desirable owing to their high specific strength and rigidity. Traditional recycling methods for these products such as thermal decomposition cause ...considerable damage to the carbon fibers. In search for better recycling methods, we explored the use of electrical treatment for the separation of resin. Herein, we investigated the effects of annealing on the separation of resin from a CFRP cross-ply laminate molded from unidirectional prepreg (carbon fiber/epoxy) using electrical treatment. The annealing of the CFRP cross-ply laminate 0°/90°2s was performed at temperatures ranging from 60 °C to 450 °C, followed by the electrical treatment. Experimental results demonstrated that the separation of resin, without the carbon fiber damage, could be achieved by annealing at temperatures close to the epoxy decomposition temperature. For the non-annealed CFRP specimens, the separation of resin was achieved with considerable damage to the carbon fibers.
The feedstock recycling of carbon fiber reinforced plastics (CFRPs) is typically conducted by either thermal decomposition or dissolution methods for resin separation. A common issue in the recycling ...processes is that neither oxygen nor solvents can easily penetrate dense CFRP; therefore, penetrating diffusion paths such as voids is expected to improve the separation efficiency. This study presents voids formation characteristics by low-temperature annealing as pre-treatment in typical epoxy-based cross-ply CFRP laminates. The void characteristics were evaluated by electrical treatment and observations after the annealing in the air or N
2
atmosphere. Annealing in air resulted primarily in ply delamination and matrix cracking through slight oxidative reactions. By contrast, annealing in the N
2
atmosphere denatured the epoxy resin, resulting in the formation of voids and swelling that reached the interior of the specimens. The void characteristics could be controlled by the atmosphere in the low-temperature annealing, leading to the penetrating diffusion paths.
A catalytic method for the C–H alkylation of cubanes is described. Some hydrogen atom transfer catalysts enable the direct abstraction of a hydrogen atom from the C–H bond of cubanes, followed by ...conjugate addition of the generated cubyl radicals to electron-deficient alkenes. Synthetic applications of the functionalization method developed are also described.
A novel method of introducing an oxygen functionality into a cubane core was developed using a transition-metal-catalyzed directed acetoxylation methodology via C–H activation. The obtained compounds ...were derivatized into cubane analogues of pharmaceutically relevant structural motifs, namely, acetylsalicylic acid and coumarin motifs, which could potentially act as bioisosteres of these scaffolds.
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