Abstract: Vinylidene fluoride polymer films are provided having improved dielectric constants and tan .delta. values and which do not exhibit substantial shrinkage when heated to temperatures below the crystalline melt point. Processes for preparation of such films are presented.

Abstract: A copolymer of 20 to 33 mol. % vinylidene fluoride, 15 to 45 mol. % of ethylene and 30 to 65 mol. % of tetrafluoroethylene gives a dielectric material having a large dielectric constant of 4.0 or above and a small dielectric dissipation factor (tan .delta.) of 0.8% or below, and is suitable for use as a condenser film.

Abstract: The ion distribution in a high molecular film is controlled by selectively altering the ion pattern under a combination of heat and electric field where at least one of the latter is applied to the film in the desired pattern. Selectively altering the ion pattern is accomplished by any one of the following: lateral shifting of ions in one film, removal of ions from one film and concurrent injection into a second film; removal of ion disassociative molecules from one film and concurrent injection into a second film. Ions which color the film are preferably used to permit visual inspection of the ion pattern. The film with the ion pattern is particularly adapted for electro-photographic copying.

Abstract: A layered electret retaining a high surface potential for a prolonged period of time or substantially permanently consisting of a laminate of a plurality of unit electrets which are formed of a sheet of a synthetic plastic material, each side of the laminate having been covered by a thin film of a high molecular weight substance having a higher electric resistivity than that of the material of the unit electrets. In one modification, the thin film of the high molecular weight substance has been, in addition, interposed between adjacent unit electrets.