In general plastics are weaker and less rigid than metals. Because these factors of strength and deformation are important in design, careful engineering is required to insure success. This eventually develops into a difficult technical consideration, because the properties of plastic are complex and vary quite differently from those of metal. It is this behavior of plastics, in combination with the involved stresses and environment that exist within a refrigerator liner, which requires tests that are neither short nor simple.

Since this information may be applicable to other similar design programs, the purpose of this paper is to discuss methods that were considered useful and relevant in an evaluation of the ability of a plastic food liner to withstand stress, impact, and other anticipated use requirements. It is not this paper1s purpose to discuss product format, insulation merit, element of machine design, U.L., or toxicity aspects.