The primary application for cryogenic insulating foams will be fuel tank applications for fueling systems. It is crucial for this insulation to be incorporated into systems that survive vacuum and terrestrial environments. It is hypothesized that by forming an open-cell silica-reinforced polymer structure, the foam structures will exhibit the necessary strength to maintain shape. This will, in turn, maintain the insulating capabilities of the foam insulation. Besides mechanical stability in the form of crush resistance, it is important for these insulating materials to exhibit water penetration resistance. Hydrocarbon-terminated foam surfaces were implemented to impart hydrophobic functionality that apparently limits moisture penetration through the foam. During the freezing process, water accumulates on the surfaces of the foams. However, when hydrocarbon-terminated surfaces are present, water apparently beads and forms crystals, leading to less apparent accumulation.
The object of this work is to develop inexpensive structural cryogenic insulation foam that has increased impact resistance for launch and ground-based cryogenic systems. Two parallel approaches will be pursued: a silica-polymer co-foaming technique and a post foam coating technique.
Insulation characteristics, flexibility, and water uptake can be fine-tuned through the manipulation of the polyurethane foam scaffold. Silicate coatings for polyurethane foams and aerogel-impregnated polyurethane foams have been developed and tested. A highly porous aerogel-like material may be fabricated using a co-foam and coated foam techniques, and can insulate at liquid temperatures using the composite foam.
NASA is currently involved with varying space and terrestrial projects that would greatly benefit from more efficient cryogenic insulation to reduce fuel boil-off. Hydrogen quality testing methods require terrestrial sampling lines that would benefit from this insulation by reducing line losses for more accurate representation of tank holdings. Moreover, rockets and orbital depot systems require insulation that will maintain liquid fuel during liftoff, and during the initiation of orbit.
This work was done by David M. Hess of InnoSense LLC for Kennedy Space Center. For more information, contact the Kennedy Space Center Innovative Partnerships Office at (321) 867-5033. KSC-13569