Large-celled extruded foams with zero-ozone depletion potential for insulating billet applications

Abstract

Phase out of specific refrigerant use within extruded polystyrene foam requires reformulation to meet ever-evolving regulatory considerations; elimination of hydrochlorofluorocarbon-based blowing agents is one such example. While this transition has been applied to insulation sheathing addressing the bulk of extruded polystyrene use, large-celled formulations intended for billet applications can differ considerably from these. Reformulation, however, cannot result in unacceptable changes which impact desired performance. Further, the differences inherent to hydrochlorofluorocarbon and hydrofluorocarbon blowing agents require additional attention around appropriate co-blowing agent and resin selection strategies. The unique approaches for large-celled foams to balance the often competing needs and relationships between material selection, processing conditions, expansion behavior and end-use properties are described. Large-celled hydrofluorocarbon-based foams with zero-ozone depletion potential that can perform in a manner consistent with hydrochlorofluorocarbon predecessors are demonstrated.