The morphology and the crystallization of blends of poly(vinylidene fluoride) (PVDF) with polyamide-6 (PA-6), and with poly(butylene terephthalate) (PBTP), were investigated in detail by electron microscopy and by DSC. In some of the blends, the dispersed component exhibits rather small particle sizes and, followingly, a high number density of the dispersed particles which is in the order of magnitude of, or exceeds the number density of the usually nucleating heterogeneities. In these blends, the crystallization of the dispersed component proceeded in two steps, induced by different nucleating species ("fractionated crystallization"). The nuclei concentrations in the components and the specific interfacial energies of the PVDF nucleation steps were estimated. An unusual type of fractionated crystallization occurs in some cases: matrix and disperse phases crystallize completely coincident due to a specific mutual nucleating efficiency of both components. An estimation of the interracial energies involved suggests a nucleating activity of PVDF crystals for PA-6. Moreover, a rise of the crystallization temperatures of the PA-6 and PBTP matrix phases is observed that may indicate a migration of nucleating impurities during melt processing from PVDF towards the second component.
The equilibrium melting temperature, Tm,0, of poly(ferrocenyl dimethylsilane) (PFDMS) is re‐investigated using two PFDMS homopolymers and a PS‐b‐PFDMS copolymer (PS: polystyrene). The melting temperatures of samples crystallized at different crystallization temperatures, Tc, were found to depend in a nonlinear fashion on Tc. Consequently, the Hoffmann–Weeks approach fails in determining Tm,0. The more reliable Gibbs–Thomson approach results in a Tm,0 = (215 ± 11) °C for the PFDMS homopolymers, and a Tm,0 = (179 ± 5) °C for the PFDMS microphases in the lamellar PS‐b‐PFDMS diblock copolymer.magnified image
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