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General problems of structural changes which occur at storage of two‐phase crystalline polymers with a metastable structure at room conditions are considered on the example of a vinylidene fluoride ‐ hexafluoropropylene copolymer. The physical aging occurs in flexible‐chain crystalline polymers (polyethylene, fluoropolymers under consideration, etc.), where, due to low glass transition temperatures, the liquid‐like dynamics of amorphous phase chains is realized at room temperature through cooperative micro‐Brownian motions with short relaxation times. Taking into account that covalent‐bound sections of the chains of the amorphous phase can enter the crystallites, the noted mobility may initiate changes in the size of the latter. Such a possibility is proved by the example of the noted copolymer. At low‐temperature crystallization of a vinylidene fluoride ‐ hexafluoropropylene copolymer from a solution the formed α‐phase crystals have little perfection. The size of the crystals increases when the films are stored in room conditions. Because of the crystal polymorphism, at the same time a certain fraction of γ‐phase crystals which are present in initial films undergo a polymorphic transformation γ → α. These processes lead to an increase in crystallinity. Moreover, during such processes additional structuring is observed, which is reduced to the displacement of various kinds of intra‐chain defects into the amorphous phase (and especially into the surface). Since the copolymers under study are ferroelectrics, they were studied by piezo force microscopy. It was found that despite the crystallization predominantly in nonpolar α‐phase, piezo force microscopy revealed a domain structure, which formation mechanism is discussed. The structural changes at physical aging of the films affect the character of the noted domain structure. Thus, it is suggested that the mechanism of the described structural changes is realized through the developed cooperative mobility of the chains in the amorphous phase, which characterizes the processes of rotational diffusion.

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An effect of Rhodamine 6G dye introduced into vinylidenefluoride and tetrafluoroethylene copolymer on a number of its structural and electrical characteristics has been detected. It was shown that at film crystallization, the inserted dopant shifts the equilibrium distribution of isomers to the side of increasing concentrations of chains with the conformation of a planar zigzag. The dye introduced strongly increases ac conductivity, especially at high electric fields. The investigation of high voltage polarization under bipolar external field conditions shows slow switching of gigantic current which is observed at fields lower than coercive ones. The estimation of the charge density indicates the non-ferroelectric nature of the phenomenon observed. The analysis of the data shows that in the system, Maxwell–Wagner relaxation processes take place, which lead to the space charge formation in the polymer matrix. It is established that current switching observed must be attributed to the relaxation of the space charge field.