Durability of a Soya-Derived Flexible PU Foam for Mattresses: Effects of Different Artificial Aging

The aim of this work is to investigate the durability on long timescales of an innovative sustainable soy-derived PU flexible foam used for mattresses fabrication. The foam samples have been submitted to two different accelerated aging procedures, by exposure in an environmental chamber at controlled temperature, humidity, and UV radiation, and by performing cyclic fatigue loadings in a mattress aging station. The effects of the changes on structural properties and foam comfort levels (i.e., hysteresis loss, surface firmness, and resistance to bottoming out) have been evaluated after both artificial weathering experiments. The results show that the different weathering factors reduce the foam comfort factors in static conditions, causing a progressive softening of the aged samples accompanied by a decrease of their ability to distribute body weight. Oxidation phenomena due to UV weathering mainly affects the chemical structure of the polyurethane foam, giving a yellowing of the material, whereas the fatigue cycles determine a partial disruption of the cellular structure, with the formation of very large pores.