Crystallization and melting in poly(ethylene oxide) are followed in real-time using hotstage atomic force microscopy (AFM). Hedritic morphology is observed at various stages of development. Lamellar growth rates are estimated and found to agree with values obtained by conventional optical microscopy. The presence of a depletion zone is detected at the crystal/melt interface.

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The processes of melting and crystallization of poly(ethylene oxide) are followed in real time at elevated temperature by atomic force microscopy using a simple hot stage apparatus. Hedritic development at a temperature of 5~7°C is monitored, including the process of lamellar splaying to yield a spherical morphology. Crystal growth kinetics are measured by monitoring the growth of individual lamellae and found to agree with those obtained by conventional optical microscopy.

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The binary blend of poly(ethylene oxide)/atactic poly(methyl methacrylate) is examined using hot‐stage atomic‐force microscopy (AFM) in conjunction with differential scanning calorimetry and optical microscopy. It was found possible to follow in real time the melting process, which reveals itself to be nonuniform. This effect is ascribed to the presence of lamellae having different thicknesses. The crystallization process of poly(ethylene oxide) from the miscible melt is also followed in real time by AFM, affording detailed images of the impingement of adjacent spherulites and direct observation of lamellar growth and subsequent polymer solidification in the interlamellar space.© 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2643–2651, 1998

In studies of spherulitic crystallization in polymers, many questions pertaining to the mechanism of the crystallization process have remained unanswered. A currently accepted view describes the development of spherulites from a framework of individual dominant lamellae that splay apart and branch (e.g., by a dislocation mechanism). This model, in addition, assumes that the space between the dominant lamellae is filled by subsidiary lamellae. In the center of a spherulitic entity, there is a hedritic core that occupies a relative volume that depends on the level of maturity of the spherulitic development. Typical hedritic views consist of lamellae that have a flat stack, or sheaflike, splaying appearance depending on the angle and depth of observation with respect to the central stack of lamellae. Visualization of the three-dimensional appearance of these hedrites by atomic force microscopy (AFM) and the observation of their growth in situ are the subjects of this article. First, we describe AFM studies of hedrites observed at etched surfaces of p-isotactic polypropylene 492 VANCSO ET AL.porting splaying, branching via dislocations, and development of curved lamellae is presented. In the second part, we describe real-time hot-stage AFM in situ observations of the hedritic growth in poly(ethy1ene oxide) (PEO) and poly-(E-caprolactone) (PCL).

In this paper, we study the relaxation behavior of initially amorphous poly(ethylene terephthalate) (PET) films drawn, at 80°C using a draw rate of 2 cm/min, to a draw ratio (A) from 1 to 5 and then quenched to room temperature. These films were then heated at different temperatures from 68 to 80°C for different times and their orientation determined. The orientation measurements were performed by transmission infrared spectroscopy and the bands used for the determination of orientation were those at 1340 and 970 cm-' for the trans conformers, normalized using the 1410 cm-' benzene ring vibration. The crystallinity was determined by thermal analysis. It is shown that when PET is drawn to A values up to 2-2.5 (before stress-induced crystallization), the orientation relaxes rapidly a t temperatures close to the glass transition temperature of PET. For A values of 3 or higher, the orientational relaxation of the amorphous regions is hindered. This effect is ascribed to the development of strain-induced crystallites, which are believed to act as pseudo-crosslinks.