Ranger Compositi S.r.l. - HIKARI GMC Member

The Green Moulding Compound (GMC®) is a groundbreaking composite material that emphasizes both eco-sustainability and strong mechanical properties. Developed for the Hedera domestic vertical garden system, GMC® offers a promising solution for greener construction materials. Traditionally, composite materials have been favored in light transport and sporting goods due to their lightweight and high-strength characteristics. However, their widespread adoption has been limited by issues such as low eco-sustainability, primarily due to the use of thermosetting polymers, which are challenging to reuse and recycle.
To address these concerns, Hikari, an innovative start-up from Italy, collaborated with the University of Ferrara's Polymers and Composites Laboratory to create GMC®. This new material is similar to standard sheet moulding compounds (SMC) and bulk moulding compounds (BMC) but replaces conventional components with environmentally friendly alternatives. Specifically, glass fibers are substituted with natural flax fibers, and a polyester resin with significant natural content (around 50%) is used as the matrix. Additionally, mineral fillers are replaced with food processing waste, significantly enhancing the material's eco-sustainability, as indicated by carbon footprint analyses.
The GMC® is utilized by Hikari in the Hedera vertical garden system, where a balance between environmental impact and mechanical properties is crucial. The system requires materials that not only support the structure but also have a low carbon footprint, necessitating a reduction in glass fibers in the composite formulation. However, using plant-based fibers like flax presents challenges, primarily due to their lower rigidity and strength compared to synthetic fibers like glass. This disparity necessitates optimizing the part design to ensure the material meets the necessary strength and durability thresholds.
Another significant challenge is the fibermatrix interface. Plant-based fibers are hydrophilic, primarily due to their cellulose content, while most polymer matrices are hydrophobic. This incompatibility can hinder efficient load transfer between the fibers and matrix. To overcome this, coupling agents are employed to enhance the interface bonding. Additionally, careful drying of the fibers before impregnation is essential to prevent hydrolytic degradation of the polyester matrix, which would weaken the composite.
The production process of GMC®, which is patent-protected, also faces obstacles. Flax fibers tend to clump together, forming bundles that can create weak points within the material. While reducing fiber length can mitigate this issue, it also diminishes the strengthening effect of the fibers. Thus, achieving a balance between fiber dispersion and mechanical performance is crucial. The molding process must ensure that the resin adequately flows to separate these bundles, avoiding stress concentration points that could lead to mechanical failure.
Thermal degradation during processing is another concern. While cellulose, the main component of plant fibers, degrades at temperatures around 250°C, it is vital to keep processing temperatures below 200°C to avoid degrading hemicellulose and lignin components, which could compromise the material's mechanical integrity and appearance.
Through collaboration with the University of Ferrara, Hikari has successfully addressed many of these challenges, leading to the commercialization of GMC® in the Hedera vertical garden system. This application demonstrates not only the material's mechanical robustness—verified by resistance tests where the material withstood loads of 3800 N—but also its lower environmental impact compared to traditional composites. An external assessment confirmed that GMC® has a substantially lower carbon footprint, making it a viable, eco-friendly alternative in composite material applications.
In summary, GMC® represents a significant advancement in sustainable materials, combining environmental benefits with functional performance. Its development highlights the potential for innovation in material science to contribute to more sustainable construction practices.