Design and engineering of 100% polyurethane sandwich structure for sanitary application

This work is based on a team research project developed at DUNA-Corradini SpA. The project consists in design and characterization of innovative composite structure, used principally for the production of shower trays for sanitary application. Starting from a set of existing PUR materials trademark of DUNA-Corradini SpA, DUNAPOL® T products, we worked to combine them to obtain a new composite sandwich structure for 100% PU based shower trays manufacturing, avoiding the use of glass fibres and styrene-based materials in the final product. The final prototype must be able to satisfy costumer’s requirements in terms of mechanical properties, weight, and production cost. A brief literature review is presented, regarding polyurethane chemistry, studied materials and sandwich structures. Mechanical tests were performed to study mechanical behaviour and to classify DUNAPOL® T products for sandwich production. Impact tests were performed on different sandwich structures to identify best materials for both “skin” and “core”, studying the main parameters that affect impact resistance of polyurethanes. Optimization procedure was applied working on PU formulation, core density and skin thickness principally. Materials for sandwich structures production able to withstand requirements in terms of impact resistance, were identified. Final sandwich structure obtained is characterized by high weight saving (up to 60%), good dimensional stability and low cost related to raw materials used. Finally, production of shower tray prototypes with different coatings was performed. Production process suitable for 100% PU-based shower trays was defined, exploiting DUNA-Corradini know-how in PU industry. Production process steps are then validated at DUNA-Corradini laboratories, to obtain shower tray prototypes. Then, a FMEA, failure mode and effect analysis, is applied on the production process considered, based on sandwich and shower tray production carried out in laboratory.