The Potential in Next-Generation Recyclable Composites with Plant-Derived FRP

Yamaha Motor has engaged in R&D of fiber-reinforced plastics (FRP) for over 60 years and has applied its findings and technologies to the development and manufacture of boat hulls, swimming pools, and other products. However, in terms of resource recycling and other aspects, there is still room for further development with composites using materials like glass fiber and carbon fiber, and improvements to not just the materials but also construction methods are being sought after.

It is amidst such developments that Yamaha Motor has begun new R&D projects to explore the possibilities offered by plant-derived composites. In this issue, we will introduce a next-generation recyclable composite using flax fiber.

Close Teamwork in the Daunting Challenge to Adapt Plant-Derived Materials

Linen is a textile made from flax fibers and is used mainly as a fabric for clothing. Flax is a plant actively cultivated in France, Belgium, and other eastern European countries, and the flaxseed oil extracted from seeds is used as a raw material for paint and ink, but has also drawn attention in recent years for its health benefits.

“Flax has a wide variety of applications, but when it comes to using it in industrial products, the hurdle suddenly shoots up,” says Tomoki Ito from the Manufacturing Technology Center with a wry smile. Ito is currently working closely with his senior engineer Kenjiro Fujii to research and develop fiber-reinforced plastic (FRP) using flax fibers.

FRP is a strong and lightweight composite material utilized for boat hulls and many other applications and generally uses glass fiber or carbon fiber. Yamaha Motor has been working with this material for more than 60 years, but “FRP still has room for development in terms of resource recycling and other aspects,” says Fujii. “We believe that using plant-derived materials is one effective approach to also pass the FRP machining expertise and technologies we have amassed thus far on to the next generation.”

Accelerating the R&D of Recyclable Composite Materials

As a raw material for composites, flax fiber does present several disadvantages. Some standout examples are how it frays in an irregular manner—something typical with natural materials—or absorbs moisture more easily compared to glass fiber. “It’s already a difficult material to handle to begin with, but what we envision is adapting it to a wide range of product categories. By setting strict requirements and a difficult target to reach, we believe we can expand the possibilities for the material across Yamaha’s many different business fields,” explains Ito.

That “difficult target” is the SuperJet stand-up personal watercraft. On top of the material not being particularly water-resistant, it also needs to be strong enough to withstand heavy water pressure. After repeated trial and error, the duo eventually made some headway and the required levels of performance and exterior quality came into view. Their first step from there was to exhibit their results at an in-house technical exhibition to other Yamaha engineers. The high level of interest from fellow professionals working in other businesses gave Ito and Fujii added confidence and their work was also exhibited at the Japan International Boat Show 2024.

The flax fiber is laminated with a process called vacuum infusion, in which the resin is injected into a mold and impregnates the fiber via vacuum pressure. “The reason we can do this in the first place is because Yamaha’s commitment to these processes gives us so many options to choose from,” says Fujii. His colleague Ito feels they are making good progress: “By closely examining what we’re working with, we’ve steadily found out what’s key to handling this material. We’re getting a better idea of how to make the most of the material too, like its gentle appearance or elastic qualities.” It is safe to say that Yamaha Motor is ramping up the pace of its R&D efforts toward practical use of this and other recyclable composite materials.

Message from the Editor

After interviewing Ito-san and Fujii-san, I asked them about their relationship as colleagues. “I think having the attitude of ‘Let’s give it a try first’ is an important quality for an engineer, and Ito-san has that,” commented Fujii-san. The two don’t have clear role boundaries either; they think together, do hands-on assessments together, and when they run into difficulties, they wrack their brains to find a solution together. “Some people only want to take action once they’ve been convinced of something,” continues Fujii-san. “But with this kind of exploratory R&D, it’s really important to ‘give it a try first.’ For Ito-san to really understand that firsthand through this project, I’ll be giving him gentle pushes from behind to help guide him.”