form or in a fully or partially inflated form for many polymer solvent systems foams tend to collapse after exiting the spinning orifice as the solvent vapor condenses inside the cells and or diffuses out of the cells to obtain low density inflated foams inflating agents having low boiling temperatures are usually added to the spin fluid suitable inflating agents that can be used include partially halogenated hydrocarbons such as hydrochlorofluorocarbons and hydrofluorocarbons perfluorocarbons and hydrofluoroethers other organic solvents and gases having low boiling temperatures can be used when very low density foams 0 0005 0 1 g cm 3 are desired as spun foams can be post inflated using the procedures described in blades parrish and bonner foam fibers are normally spun from a round cross section spin orifice however an annular die similar to the ones used for blown films can be used to make foam sheets it should be noted that the 2gt 3gt and 4gt polymers herein are intended to include copolymers with recurring units of up to about 15 monomer as well as homopolymers whether used for making foams or plexifilaments moreover it has been found that the addition of monomers to a homopolymer can decrease the cloud.