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The purpose of this work is to obtain a better understanding of the morphology of polyphosphazenes and to establish some general morphological characteristics. Solution cast, stretched and annealed films of poly(bistrifluoroethoxyphosphazene), PBFP, and poly(bisphenoxyphosphazene), PBPP, have been investigated by electron and optical microscopy. Thin and thick films were prepared using different solvents. Films were cast and stretched below as well as above T(1), the thermotropic transition of each polymer. In the case of PBFP its T(1) transition was established through birefringent-temperature measurements and orientational changes were measured as a result of heat cycling stepwise through T(1). Thin specimens were oriented on electron microscope grids using a mechanical stretcher; thicker films were drawn by hand at various temperatures, too. Orientation was effectively induced through casting on hot liquid surfaces at temperatures > T(1). PBPP exhibits a layer (domain) morphology of high crystallinity and orientation under these conditions. Dislocations or stacking faults can be recorded in darkfield in PBPP but the low stability of PBFP to the electron beam does not permit dark-field images to be recorded. Optical microscopy was used to record cast film textures.

The morphologies of highly oriented PET films, crystallized in a longitudinal flow gradient, were examined using transmission electron microscopy, differential thermal analysis, thermomechanical analysis, birefringence measurements, and mechanical tensile tests. The morphology in the as‐drawn state of the samples consists of oriented single micellar blocks which are embedded in the amorphous matrix. Annealing above 180°C causes a morphological transformation into lamellalike crystals, which are formed by lateral crystallization, preferably at the sidefaces of the micellar blocks. An interpretation of the mechanical behavior is given in accordance with the morphological model.

Epitaxial growth of polymers on various substrates has been reported on numerous occasions1-10J6J6; however, in most investigations ionic salts or organic crystals were used as substrates. The interest in these systems arises from the use of the crystals as nucleation agents for the polymers. On the other hand, there is considerable interest in coupling agents for polymer blends and multilayered films. Epitaxy in blended polymers can substitute for or replace the adhesive because epitaxially oriented interfaces may provide strong bonding? It is the purpose of this note to report epitaxies of polyethylene and paraffin on oriented polypropylene, polybutene-1, and isotactic polystyrene substrates. EXPERIMENTAL MaterialsThe materials used for the experiments were polypropylene, type PPN and PPH, from Hkhst; polyethylene, Lupolen 6021 DX from BASF wax A409 and polybutene-1 (PRl), Vestolen BT, both from Chemische Werke Hills; isotactic polystyrene (ips) from Polyscience, Inc., and paraffin, T,,, = W C (n-aa) from Merck. This paraffin has a much shorter chain length than wax A409, which has a number-average molecular weight of about 2 x 1W. ProcedureThin oriented substrate films of polypropylene, polybutene-1, and isotactic polystyrene were prepared according to the method of Petermann and Cohil.'' The thin films were cut into 3x 3 mm pieces and mounted on electron microscope grids. Thin unoriented films of polyethylene, wax, and paraffin were cast from 0.1% solutions in o-xylene. These films were then cut to the same size as the oriented films, floated on distilled water, and then transferred to the oriented films. Subsequently, the layered films were heated in an air oven to well above the melting point of the unoriented films for 15 min (polypropylene-polyethylene: 160°C. polypropylene-wax: 13OT, polypropylene-paraffin: 90T, polybutene-l -wax: 130"C, polybutene-1-paraffin: WC). The drawn films of isotactic polystyrene were first crystallized a t 180'C for 30 min and subsequently heat treated with polykhylene at 1WC and paraffin at 90°C. The heat-treated samples were examined in a Phillips 400 T electron microscope a t 100 kV using electron diffraction, dark-field, and bright-field techniques. RESULTS AND DISCUSSIONIn Table I the morphologies and crystal orientations of substrates and recrystallized layered polymers are documented. Figure 1 shows a bright-field TEM photograph of the PP-PE morphology. A sketch of PP-PE is inserted in this figure. Figure 2 is an electron diffraction pattern of this specimen. The molecular axis (c axis) of the PP substrate film is horizontal. This f w r e exhibits two sets of diffraction patterns of PE with both molecular axes in the same plane, but displaced by f5(Y from the molecular axis of the PP. All the diffraction spots of the PE can be indexed as OM. In Figure 3 the electron diffraction pattern of the PE together with the PP substrate is illustrated. For clarity only one set of PE diffraction spots is shown in Figure 3. The two sets of diffraction patterns arise from two differe...