the cloud point pressure however foam fibers may be obtained rather than plexifilaments even at spinning pressures slightly below the cloud point pressure of the solution spin agents and co spin agents are the same as those noted above for the plexifilamentary film fibril materials nucleating agents such as fumed silica and kaolin can be added to the spin mixture to facilitate spin agent flashing and to obtain uniform small sized cells foams can be obtained in a collapsed 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.