Abstract

Thermoplastic sandwich panels are attractive for automotive applications since they can be readily formed into the light weight complex structures with good impact resistance and high flexural rigidity. In this experimental study, the extent of enhancement in properties achieved through the use of thermoplastic composite skins combined with a recycled thermoplastic core is demonstrated. The thermal behavior of polypropylene (PP)-based recycled materials and the possibility of turning them into the sandwich panels via a plastic extrusion processing were investigated. A sheet extrudate of recycled thermoplastic composite was sandwiched between two thermoplastic skins on both sides to make the sandwich panels. The core material composed of recycled polypropylene (RPP) and shreds of recycled PP/Fiberglass (e.g. twintex scraps) with the weight ratio of 1:1. A commercial thermoplastic skin, TWINTEX, which is a roving made of commingled E-Glass and polypropylene filaments woven into highly conformable fabrics, is used as the face sheets to bond with the core material.
A good understanding of principles for manufacturing sandwich panels and performing some experimental optimization leads to making high-strength and strongly-bonded sandwich panels. Results of the mechanical tests (3-point bending and peel-off test) show that recycled sandwich panels offer better mechanical performance compared with their honeycomb counterparts in terms of flexural strength and skin-to-core bonding and they are more resistant to delamination. The big issue is that they are high-weight materials compared with honeycomb sandwich panels. So we applied some foaming processes using chemical foaming agents to reduce the density of the core. A significant reduction in sandwich panel’s weight and better mechanical performance could be achieved.