Recycled polyethylene bottle caps as sandwich panel circular honeycomb: Experimental and numerical approach

This work describes aluminium skin sandwich panels made of recycled polyethylene (PE) bottle caps as a sustainable honeycomb core. A full factorial design is carried out to identify the effects of the orientation of the caps (single and alternated caps), skin roughness (smooth and rough substrate) and the type of adhesive (epoxy or polyester polymer) on the mechanical properties of the panels. Numerical analysis is performed to better assess the failure mechanisms involved. Sandwich panels made with epoxy adhesive, smooth aluminium skin and single oriented caps obtain greater mechanical properties at failure compared to the alternative levels of the factorial design. Increased results are observed for core shear stress (0.38 MPa), facing stress (56.75 MPa), core shear modulus (16.70 MPa), and flexural modulus (1437.47 MPa). This performance reveals an alternative recycling route for used PE bottle caps in structural and sustainable applications.