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This paper reports on the development and the optimization of a thermoforming process (compression molding) for thermoplastic sandwich panels. The skins of the panels are fabricated from polypropylene (PP)/continuous glass fibers dry prepregs in the form of a commingled fabric. The use of two different types of core material has been used, a PP foam and a PP honeycomb. Additionally, two alternative methods for the thermoforming process have been analyzed, using either a one‐stage or a two‐stage process. In the one‐step process, skin molding and skin‐core bonding are carried out simultaneously. In the two‐stage process, the skins are first thermoformed and then bonded to the core as the second stage. The influence of the selected process parameters on the mechanical properties of the panels has been experimentally investigated, leading to the identification of the preferred processing conditions. Polym. Compos. 25:307–318, 2004. © 2004 Society of Plastics Engineers.

In this article, a procedure for recycling of polypropylene (PP)-based sandwich panels is presented. PP/glass laminates as the skins and PP foam as the core material are used. The waste panel is converted into short-fiber composite material. The panel is first ground by a mill and homogenized in a mixer or an extruder, then the pellets are re-ground and injection molded. The influence of mixer parameters and fiber content on the mechanical and physical properties of the recycled material is experimentally investigated. The orientation and length of the glass fibers are measured using an optical microscope; SEM analysis is used to characterize the morphology of injection-molded samples.

ABSTRACT:In this work, a thermoplastic sandwich panel was designed, produced, and tested for use in insulating walls of containers for food transportation. A sandwich construction comprising a poly(ethylene terephthalate) core and polypropylene/glass fiber skins was evaluated as possible replacement of systems consisting of polyurethane foam in combination with unsaturated polyester glass-reinforced skins that are currently used for the manufacture of these structures. Factors were taken into account to satisfy the simultaneous need of thermal insulation and adequate mechanical properties that are required for the production of large flat panels 100-mm thick. The influences of different manufacturing processes and skin-core adhesion on the mechanical properties of this thermoplastic sandwich were investigated and are discussed in This paper was presented at the conference ICCM-17 on Thermoplastic Matrix Composites.