Topological Mechanism of Nucleation of Polymers

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Topological mechanisms of the nucleation of polymers have been studied. The direct evidence was shown for the first time that nuclei have been formed during the "induction period = initial stage) of the nucleation by means of Small angle X-ray scattering (SAXS). The scattering intensity of the nuclei was significantly increased by adding the nucleating agents. A new mechanism of nucleation under shear flow was presented : random coiled polymer chain can be easily elongated by pinning effect by fixed "pins" or dusts in the melt, which results in formation of bundle type nuclei and so called "shish" morphology. The onset mechanism of spherultic morphology from a single lamella was also studied. Due to topological nature of long chains, accumulation of strain on the surface of a single lamella can be seen, which results in screw dislocation and branching of lamellae will start. New method to determine the reliable melting temperature of thin lamellae of polymers was established. Using this method new method of determining the equilibrium melting temperature was also established.