Technological Area:

This invention is about the carbon fiber reinforced nano-composite swimmer fin of sport wear industry manufacturing and selling equipment used in underwater diving and scuba diving, underwater harpoon hunting, underwater photography, underwater search and rescue and sport activities such as water polo and swimming.

Current Situation of the Technique:

The composite paddle of the swimmer fins of today are consisted of composite carbon fiber sheets. According to the information obtained from the manufacturing company in this industry, it’s determined that traditional carbon/epoxy swimmer fins are frequently suffering from fraction as a result of the repulse force of the swimmer.

There are various studies carried out on materials to make the items used in daily life more durable and useful. Some of the multi-walled carbon nanotube studies are as follows.

In the patent application numbered JP2006045057A, “Double Walled Carbon Nanotube Manufacturing and Application Method” is described. Basically, it’s a two concentric solid material which generally contains a cylindrical graphene layer and consisted of carbon nanotubes that are hollow as much as more than %70 of its’ weight. An electron emitting material contains a surface consisted of multiple emissive tubules in basic and these multiple emissive tubules are generally nanotubes that have two graphene layers.

In the patent application numbered US7150864B1, “Ropes Consisted of Single Walled and Double Walled Carbon Nanotubes” are described. The invention is about a method using a catalytic system intended to support the enlargement of preferably single and double walled carbon nanotubes instead of using bigger multi-walled carbon nanotubes. Carbon nanotube ropes are made of single and/or double walled carbon nanotubes. But there aren’t enough studies on enhancing the durability of swimmer fins.

It will be an important development to have a durable product with long-life use that has no complex production stages for swimmer fins in sports field.

Invention Definition:

This invention is the carbon fiber reinforced nano-composite swimmer fin that can overcome the disadvantages mentioned above and its’ characteristic is; being a durable product with long-life use, that has no complex production stages for swimmer fins in sports field.

With the academical studies we have conducted to eliminate the ease of vulnerability on swimmer fins and by modifying the carbon/epoxy composites which we have obtained positive results in laboratory environment with multi-walled carbon nanotube and we created nano-composite materials. By applying this nano-composite material on the sheet part of swimmer fins, a more durable structure has been obtained and the regarding durability problem could be resolved.

The invention provides durability enhancement and improvements on some mechanical characteristics (buckling, static tensile strength, fatigue etc.) of swimmer fin.

Researches made on the material sample in laboratory environment towards tensile strength, buckling strength, fatigue strength, are positive.

Description of Figures:

The invention will be described by referring the figures enclosed, this way the characteristics of the invention will be understood and assessed more clearly, but this is not intended to limit the invention with these specific arrangements. Vice versa it’s intended to cover all alternatives, changes and equivalents which can be involved under the area the invention is defined in by the claims enclosed. It must be understood that the shown details are given only for the description of the preferred arrangements of the current invention and presented to provide the most utilizable and clear definition of both the formation of the methods and the rules and conceptual characteristics of the invention. In these figures; Figure 1 Schematic view of the production of Carbon Fiber Reinforced Nano- Composite Swimmer Fin.

Figure 2 Scanning Electron Microscope (SEM) view Carbon/Epoxy/MWCNT-OH Figure 3 View of spectroscopy of Carbon/Epoxy/Multi -Walled Carbon Nanotube- OH FTIR. Figure 4 The view of the results of the threepoint bending test.

The figures that will help out to understand this invention are numbered as specified in the enclosed figure and they’re given below by their names. Description of References:

10. Mixing Hardener and Epoxy Resin 20. Adding Carbon Nano tube 30. Mixing Mechanically 40. Applying with Hand Lay-Up Method

50. Shaping as Sheet 60. Taking It to Hot Press Mold 70. Curing 80. Mounting

Description of Invention:

This invention is produced by; mixing hardener and epoxy resin at ratios of %20 and %80 respectively (10), adding carbon nanotube at %0,5 weight (20), mixing the mixture mechanically (30), applying the mixture to carbon fiber fabrics with hand lay-up method (40), cutting it and shaping as the fin sheet (50), taking the wet fabrics to 22° angled hot press mold with heat-resistant wax paper (60), curing them for 3 hours at 100 °C and under 8 bars pressure (70) and mounting padding and wicks onto the nano composite sheet (80). (Figure 1)

In the nano-composite structure of the swimmer fin, carbon nanotubes are sticked to the fibers physically, creates a rough formation thus improves the interfacial bonds between epoxy resin and fibers and proves a working mechanism. In addition, because carbon nanotubes are chemically functionalized, they bind chemically with resin and the quality of the interfacial bond becomes stronger.

Carbon nanotubes function as a bridge between the resin and fiber, enables a balanced and efficient strength transfer from epoxy matrix to fibers and lets the sheet to be more durable against fracture damage.

Detailed Description of Invention:

The product subject to invention is produced by; mixing hardener and epoxy resin at ratios of %20 and %80 respectively (10), adding carbon nanotube at %0,5 weight (20), mixing the mixture mechanically (30), applying the mixture to carbon fiber fabrics with hand lay-up method (40), cutting it and shaping as the fin sheet (50), taking the wet fabrics to 22° angled hot press mold with heat-resistant wax paper (60), curing them for 3 hours at 100 °C and under 8 bars pressure (70) and mounting padding and wicks onto the nano-composite sheet (80). (Figure- 1)

In the nano-composite structure of the swimmer fin, carbon nanotubes are sticked to the fibers physically, creates a rough formation thus improves the interfacial bonds between epoxy resin and fibers and proves a working mechanism. In addition, because carbon nanotubes are chemically functionalized, they bind chemically with resin and the quality of the interfacial bond becomes stronger.

Carbon nanotubes function as a bridge between the resin and fiber, enables a balanced and efficient strength transfer from epoxy matrix to fibers and lets the sheet to be more durable against fracture damage. The scanning electron microscope view in Figure-2, is obtained with the ZEISS Supra 40 VP model electron microscope in Pamukkale University Central Laboratory. With a 3.000x enlargement it’s seen that carbon fibers forms a coherent structure with the epoxy/carbon nanotube matrix and interfacial bonds in between are strong.

Fourier transform infrared (FTIR) spectroscopy is a frequently used method in fundamental sciences, health sciences and engineering fields for the identification of bonds in molecular structures. This method is based on the absorption of infrared rays projected on intramolecular bonds through vibration and rotational motions of molecules.

The offsets towards low wavenumbers in characteristic wavenumbers, shows that there are strong hydrogen bonds between -OH groups. From the FTIR analysis in Figure-3, it’s understood that -OH groups form bonds with epoxy resin. The better you improve the interfacial bond between the resin and the fibers the better the strength transfer from the matrix (resin) to the fibers will be thereby the durability of the carbon nano- composite sheet material will be that much enhanced. The Functionalized Multi-Walled Carbon Nanotubes are sticked physically to fibers and bind to the resin with -OH functional groups. This way it functions as a bridge in between. The analysis is made in Pamukkale University Central Laboratory.

To see the effect of carbon nanotubes on the material strength, threepoint bending test was conducted in Pamukkale University Mechanics Laboratory. As seen in Figure-4, the buckling strength of carbon nanotube reinforced samples are %6 better than non- reinforced ones. Likewise, there are studies in literature regarding that carbon nanotubes provide strength increase on some mechanical characteristics.