Eco-friendly Sandwich Panel Based on Recycled Bottle Caps Core and Natural Fibre Composite Facings

This is the first attempt to combine disposed bottle caps and natural fibres into sandwich panels. A full factorial design is performed to identify the effects of the skin type (aluminium or coir fibre reinforced laminates) and bottle cap core packing (cubic and orthotropic) on the mechanical properties of the proposed panels. The coir fibre composite skin provides maximum core shear strength, 29 % higher than the aluminium-based panels, in cubic packing, while the flexural modulus is reduced by 45 %. An interlocking effect between the skin and the core is evidenced when coir fibre composites are used. In addition, the cubic cell packing increases the specific mechanical properties, even though with a higher density. The results highlight a promising association of green components and plastic bottle caps for secondary structural applications.