(576b) A Modeling Approach to Understanding and Improving Thermal Comfort in Polyurethane Mattress Foams

Viscoelastic memory foams are often used as a near-top layer in mattress construction due to their ability to conform to a body’s shape thereby reducing the pressure exerted on the body when sleeping. Body heat can help to soften the foam to improve its shape conforming capabilities; however, a downside of the heat absorbing attribute is that it can result in thermal discomfort. This has led to more open foam structures, which were believed to moderate the temperatures through improved air flow. More recent innovations incorporate other materials into the foam to help regulate heat (e.g., phase change material), remove odors (e.g., activated charcoal), or promote health (e.g., aloe vera, copper), etc. It is unclear how much of this innovation is based on science and how much is hype.

In order to take a more scientific approach to viscoelastic foam development, the thermal comfort aspect was explored using a multi-physics modeling approach. The model components included finite element analysis to simulate the transport of heat and moisture in a mattress in contact with a human body, a lumped-parameter model to capture the body’s heat generation and sweating response to its external environment, and semi-empirical sub-models to relate foam structure to macro-scale foam properties, including moisture and thermal diffusivities. This modeling capability allows for a more detailed analysis of how different parameters, including various foam structures and additives (as well as mattress layer construction), affect the comfort level of the sleeper.