Investigation of the Supramolecular Structure of PTFE via Two-Stage Chemical Etchingстатья
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Дата последнего поиска статьи во внешних источниках: 15 февраля 2018 г.
Аннотация:The supramolecular structure of polytetrafluoroethylene (PTFE) is studied by high-resolution electron microscopy using two-stage chemical etching of the surface, consisting in the chemical reduction of macromolecules in a solution of sodium naphthalene or sodium in liquid ammonia, followed by treatment of the surface with fuming nitric acid. The existence of regular grooves on the end faces of lamellae in the initial PTFE is proven, which leads to the conclusion that the lamellae possess a fibrillar structure. The significant size excess of the crystalline domain over the diameter of the fibrils is explained by coherent stacking of the crystalline regions of fibrils in the lamellae. The existence of fine-grained structure in the initial PTFE is found on the scale of approximately 100 mu m. It is confirmed that the radiation modification of PTFE in the melt leads to the formation of centrally symmetric structures, namely, spherulites with radial orientation of the fibrils and macromolecules.