Optimization of Polyurethane Panels Properties through Different Particle and Fiber Reinforcement

Abstract Polyurethane is a highly versatile material and depending on its structure it can be applied in several application fields. One of its main applications is insulating material for the construction sector, while the most common product shape is the rigid expanded panel. This work investigates the possibility of optimizing polyurethane expanded panels for building insulating purposes by considering different particle and fiber reinforcements. Precisely, the addition of different reinforcement percentages of bentonite, phyllite, and recycled textile microfibers (both untreated and treated with NaOH) is considered in polyurethane mixes composed of isocyanate, polyol, water, silane additive, and catalysts. For fiber reinforced samples, castor oil is additionally considered as a more sustainable polyol component in polyurethane mix. Thermal conductivity is positively reduced by increasing phyllite content; indeed, these microspheres further apport porosity to the material, so a lower density, and promotes a homogeneous, fine, and closed porosity. Besides, both castor oil and NaOH fiber treatment enhance the thermal insulating too. Since insulating materials may find application also in structural elements, stress relaxation, and compression tests are performed. Polyurethanes containing phyllite display greater stiffness and mechanical improvements for specific ranges of particle percentage. On the other hand, the fiber reinforcement exceeds the particle one by an order of magnitude in improving mechanical properties in terms of maximum load and recovery. In conclusion, polyurethane reinforcements and alternative polyols are valuable solutions towards more sustainable and performant insulating building panels and product differentiation.