Studies on premoulded pad for cryo insulation

A premoulded pad of PUIR foam of required thickness can be moulded and bonded on a cryo tank with suitable adhesive. When compared to spray foaming, defect control and density control is possible in this technique as any defective or high density pads can be rejected at the source itself. Initially pads were moulded in metallic moulds. Thermo mechanical testing was carried out on the premoulded foam and cryo requirement is met. However, there was a variation in the density in the skin and core of the pad, leading to the peeling off of the first layers during the aerothermal test. Later moulding of a foam block and slicing it into foam pads was envisaged as an effective method for obtaining uniform density pads. The thermomechanical properties meet the specifications. The pad also passed an aerothermal test simulating the launch condition.