Filling voids with plastic foam

Claim 1

TECHNIQUE FOR FILLING STRUCTURALLY CONFINED VOIDS WITH A PACKING OF CLOSED CELL PLASTIC FOAM WHICH CONTAINS A GASEOUS RESIDUE OF THE PRIMARY PROPELLANT THAT WAS UTILIZED FOR ITS EXPANSION ENTRAPPED WITHIN ITS CELL WALLS, SAID CELL WALLS BEING SUBSTANTIALLY IMPERVIOUS TO SAID ENTRAPPED PROPELLANT AND WHICH FOAM CONSISTS OF A FLEXIBLE PLASTIC MATERIAL, WHICH TECHNIQUE COMPRISES COOLING A QUANTITY OF AN EXPANDED PLASTIC FOAM FROM A NORMAL TEMPERATURE TO A TEMPERATURE THAT IS SUFFICIENTLY LOW TO CAUSE CONTRACTION OF THE GASEOUS BLOWING AGENT RESIDUUM ENTRAPPED WITHIN ITS CELLS AND TO COLLAPSE THE FOAM UNDER THE PRESSURE OF THE SURROUNDING ATMOSPHERE TO A VOLUME THAT IS LESS THAN ITS NORMAL EXPANDED VOLUME, SAID QUANTITY OF FOAM HAVING A NORMAL EXPANDED VOLUME THAT IS AT LEAST ABOUT AS GREAT AS THE VOLUME OF THE PORTION OF VOID THAT IS TO BE OCCUPIED, FILLING THE VOID WITH THE COOLED AND COLLAPSED QUANTITY OF FOAM, THEN RETURNING SAID FOAM TO A NORMAL TEMPERATURE AT WHICH IT REASSUMES AT LEAST A PORTION OF ITS NORMAL EXPANDED VOLUME THEREBY OCCUPYING SAID VOID OR CAVITY.