SynopsisIt is demonstrated that continuous filaments of rapidly crystallizing polymers, such as polyethylene and polypropylene, can he spun from the melt using an electric field as the only driving force. The molten polymer is fed into a metallic capillary forming a hemispherical drop a t the end of the orifice. An electrical field is applied between the capillary and a conducting plate held perpendicular to the axis of the orifice. Above a critical field intensity a fine continuous jet of molten polymer is drawn; rapid crystallization ensues and a continuous fiber is formed.' For fibers spun in an uncontrolled thermal environment, corresponding to ambient air temperature, and a t electric field intensities of 6 and 7 kV cm-', the properties are typically those of unoriented or slightly oriented polyolefin fibers, such as would be obtained in a conventional fiber spinning process.

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The crystallization kinetics and morphology in miscible blends of poly(vinylidene fluoride) (PVF2) and poly(1,4-butylene adipate) (PBA) have been investigated using optical microscopy and differential scanning calorimetry. Blends of PVF2 and PBA are unique in the sense that both components are capable of crystallization over a wide range of compositions. The kinetics of crystallization of both PVF2 and PBA in these blends have been investigated. During the crystallization of the high-Tm component (PVF2, Tm ≈ 175°C), the low-Tm component (PBA, Tm ≈ 60°C) acts as a noncrystalline diluent. Addition of PBA depresses the radial spherulitic growth rate and overall crystallization rate of PVF2 and affects the texture of PVF2 spherulites but does not significantly alter the nature of the nucleation and growth processes of this polymer. During the crystallization of PBA, the PVF2 phase is always partially solidified and the presence of the spherulitic microstructure of PVF2 profoundly influences the crystallization behavior and morphology of PBA. The overall crystallization rate of PBA goes through a maximum as a function of PVF2 content, which is explained in terms of the combined effects of enhanced heterogeneous nucleation and reduced linear growth rate. The mechanism of crystal growth is modified in the presence of PVF2, as indicated by a change in the Avrami exponent. In the blends, spherulitic crystallization of PBA is not observed, in contrast to the bulk crystallization behavior of this polymer. Crystallization of PBA from the blends initially takes place at the boundaries of PVF2 spherulites, but at longer crystallization times, crystallization of PBA within PVF2 spherulites is also observed. The observed phenomena are unique to blends of two crystalline polymers. IntroductionThe miscibility and phase behavior of binary polymer blends has been a subject of continuing interest for researchers from both scientific and industrial fields. Among the great variety of polymeric mixtures, those involving semicrystalline polymers are particularly interesting. This is not only because semicrystalline polymers are of prime importance from the commercial point of view but also because semicrystalline polymer blends offer the possibility of studying crystallization and crystalline morphologies in relation to miscibility in high polymers. Studies of this kind have been mainly focused on blend systems containing one semicrystalline polymer. 1-6 Blends in which both components are semicrystalline polymers, on the other hand, are more complicated and thus open up new avenues for studying the relations between phase behavior and structure development in polymeric mixtures. Of particular interest is the formation and morphology of the semicrystalline/semicrystalline state since it involves the crystallization of two different polymers, each within its specific temperature regime. The study of the crystallization kinetics in these blend systems is therefore not only concerned with the effects of blend composition and crystallization...

The phase behavior and miscibility of blends of poly(vinylidene fluoride) (PVF2) and poly(1,4-butylene adipate) (PBA), both semicrystalline polymers, have been investigated using differential scanning calorimetry and light-scattering techniques. The phase diagram of this blend system exhibits a single glass transition temperature over the entire composition range, two distinct melting transitions, and a cloud-point curve above a lower critical solution temperature of 235 °C. A depression of the equilibrium melting point of both PVF2 and PBA is observed. From the melting point data of the high-T m component, PVF2, a value for the polymer−polymer interaction parameter of χ12 = −0.19 was derived using the Flory−Huggins equation. This implies that PVF2/PBA blends are thermodynamically miscible in the melt. The extent of the melting point depression for the low-T m component, PBA, is much smaller than it is for PVF2, which is attributed to the fact that PVF2 is semicrystalline at temperatures of PBA melting. Infrared spectroscopy measurements focusing on the carbonyl absorption band of PBA reveal a slight shift in peak position toward lower frequencies due to blending, indicating that the thermodynamic miscibility of the PVF2/PBA pair arises from weak specific interactions involving the polyester carbonyl group. In spite of their miscibility, blends of PVF2 and PBA exhibit a complex phase behavior and may form multiphase systems. Of particular interest is the three-phase morphology in which two distinct crystalline phases (PBA and PVF2) coexist with an intimately mixed amorphous phase. This morphology is observed at room temperature over a very broad composition range.

Specifically substituted O-methylcelluloses, 2,3-di-O-methylcellulose and 6-O-methylcellulose (parts B and C of Figure 1, respectively), were used as cellulosic components in blends with poly (ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA). Since their hydroxyl groups (OH) form controlled intraand intermolecular hydrogen bonds, the cellulose derivatives are useful as model compounds to investigate the effect of hydrogen bonding in cellulose-synthetic polymer blend systems. FTIR (Fourier transform infrared spectroscopy) spectra of the cellulosic-PEO blend films revealed that, while the primary hydroxyl groups at the C-6 position of cellulose interact strongly with ether oxygen in PEO, the secondary hydroxyl groups at the C-2 and C-3 positions show no evidence for polymer-polymer interactions. In the cellulosic-PVA blend films the FTIR analyses suggested that the secondary hydroxyl groups between the cellulose and the PVA were engaged in hydrogen bonds, and, in addition, a hydrogen bond between the anhydroglucose ring oxygen (0-5) of the cellulose and the hydroxyl groups of the PVA was formed. Thus, these results showed the specific regiochemistry of hydroxyl groups in cellulose and its importance to the study of the miscibility in cellulosesynthetic polymer blends.