Due to continuous demands from OEM's to reduce weight and make more compact vehicles, high heat generation from vehicle has become common phenomenon. Thermal insulation is a need of the hour to cater to such demands. The temperature rise is more critical around engine areas. OEM's use many design solutions to cater to such heat build up's. One of the design solutions includes use of thermally insulating materials e.g. Foams, insulating fabrics etc…
First section of this paper deals with comparative study of polyurethane (PU) soft foam and rigid skin polyurethane foam. To define the base line, the samples were subjected to various tests to determine physical, thermal and chemical properties. Also both the types of foams were subjected to high temperature and low temperature heat ageing.
From the experiments, it was observed that soft PU foam provides better re-bounce property than rigid skin PU foam. This is an important property to be considered, when foam is subjected to compression load during fitment. Foam would regain its shape and size on removal of load and hence provides better stability. Also, thermal conductivity of both the foams is compared to check for their ability to provide thermal insulation.
Based on above results, soft PU foam was further tested for performance level tests to understand the foam behavior under simulated thermal test conditions. The thermal test method was developed to simulate heat generation during actual driving conditions. Foam was also subjected to physical test till failure including compression set.
The test results are discussed and concluded for selection of better foam for the under the hood application. The results of this study were useful for determining optimum foam structure providing good insulation with lower weight.