Studies on Recycling Silane Controllable Recovered Carbon Fiber from Waste CFRP

Abstract

During the production process of commercial carbon fiber reinforced polymers (CFRPs), a silane coupling agent is added to the carbon fiber at the sizing step as a binder to enhance the product’s physical properties. While improving strength, the silane coupling agent results in a silane residue on recovered carbon fibers (rCF) after recycling, which is a disadvantage when using recovered carbon fibers in the manufacture of new materials. In this study, the rCF is recovered from waste carbon fiber reinforced polymers (CFRPs) from the bicycle industry by a microwave pyrolysis method, applying a short reaction time and in an air atmosphere. Moreover, the rCF are investigated for their surface morphologies and the elements present on the surface. The silicon element content changes with pyrolysis temperature were 0.4, 0.9, and 0.2%, respectively, at 450, 550, and 650 °C. Additionally, at 950 °C, silicon content can be reduced to 0.1 ± 0.05%. The uniformity of microwave pyrolysis recycle treatment was compared with traditional furnace techniques used for bulk waste treatment by applying the same temperature regime. This work provides evidence that microwave pyrolysis can be used as an alternative method for the production of rCFs for reuse applications.

Reinforcement Effect of Recycled CFRP on Cement-Based Composites: With a Comparison to Commercial Carbon Fiber Powder

“…These remarkable advantages have made CFRP widely used in aerospace, construction, transportation, wind power generation, and more engineering fields [6]. However, with the expanding use of CFRP, a large amount of CFRP waste is generated [7], and it is urgent to find ways to recycle the originally expensive carbon fiber for reuse from such waste [8]. Data shows that a total of about 8,500 aircraft worldwide are expected to be decommissioned by 2025.…”

Mechanical Behaviors of Microwave-Assisted Pyrolysis Recycled Carbon Fiber-Reinforced Concrete with Early-Strength Cement

“…However, using new carbon fiber as reinforcement in FRC is often not economically feasible, as the cost of new carbon fiber is typically high. According to the “Cradle-to-Cradle” concept, waste can become a new resource for the economy or nature, and recycled chopped carbon fiber appears to be a suitable option for FRC [ 29 ]. Compared with other heat treatment methods, microwave offers the benefits of using less energy to achieve fast heat transfer, contactless and selective heating for complex mixtures, and better energy efficiency [ 30 ].…”

“…However, CFRP composite materials are not easily naturally decomposed, and traditional methods of disposing of CFRP waste, including thermal treatment, solution soaking, and physical crushing, are harmful to the environment [ 38 , 39 ], especially for waste thermosetting composites. The method of physically crushing carbon fiber to recycle it also has some drawbacks, including only obtaining chopped fibers and stubborn resin on the fiber surface [ 29 , 40 ].…”

Effect of the Chemical Properties of Silane Coupling Agents on Interfacial Bonding Strength with Thermoplastics in the Resizing of Recycled Carbon Fibers

“…Carbon fibers are lightweight materials with low density, high specific strength, heat resistance, and excellent thermal and electrical conductivity, and their applications are expected to expand not only in the aerospace industry but also in all industries in the future [1][2][3][4][5][6][7][8][9]. However, due to the high price of carbon fiber and the expensive manufacturing process, it is only used for expensive parts, such as aerospace, shipbuilding, and sporting goods, and it is difficult to expand its application to fields such as general commercial vehicles due to its high price [10,11].…”