Measurement of High Resiliency Moulded Foam Properties as a Function of Climatic Conditions

Abstract

High resiliency moulded foam is normally tested under standard laboratory conditions, e.g., 23 2 C, 50 5% RH, but other conditions may be specified. It is well known that critical foam properties such as hardness and resiliency are influencedby environmental changes. This may affect foam performance especially in automotive seating applications. Changes in seating support, durability and comfort may occur and critical safety components such as occupant sensors may be affected.

We have measuredproperty changes that result from different climatic conditions from 30 to 95 C and 0–95% RH. A number of foam chemistries both experimental and in worldwide production have been thoroughly examined for property responses after conditioning. Cushion hardness, hysteresis loss and thickness have been shown to change after environmental conditioning. Resiliency as measuredby ball reboundalso responds to climatic changes. We have analysed our extensive data for temperature or relative humidity responses andfor the combinedresponse to both of these variables. Also we are able to demonstrate combined responses of properties that contribute to seating comfort as a function of climatic conditions. Therefore, we are able to demonstrate to automotive seating designers/engineers the temp/RH ranges where an important cushioning parameter such as seating hardness (and hence H-point) is relatively consistent. Thus, important safety components such as occupant seating sensors shouldremain functional over a relatively wide range of climatic conditions. Seating of various constructions, e.g., metal pan, flexible suspension, sinespring wire, have been testedto ascertain foam responses specific to these constructions. Full details of foam seat performance after environmental conditioning will be discussed.