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Effects of carbon nanotubes (CNT) on the isothermal crystallization kinetics of poly(L‐lactic acid) (PLLA) were quantitatively investigated using the Avrami equation and the secondary nucleation theory of Lauritzen and Hoffman. CNT via grafting modification with PLLA could well disperse in the PLLA matrix and give significantly enhanced crystallization rate and crystallinity of PLLA as analyzed by differential scanning calorimetry and polarized optical microscopy. Analysis of isothermal crystallization kinetics using the Avrami equation demonstrated that CNT significantly enhanced the bulk crystallization of PLLA. Analysis of spherulite growth kinetics using the secondary nucleation theory of Lauritzen and Hoffman found that CNT could expand the temperature range of the crystallization regime III of PLLA. Values of the nucleation constant (Kg) in crystallization regimes III and II of PLLA both increased with increasing CNT contents. The Kg III/Kg II ratios were found to be close to the theoretical value 2 but were not clearly found to depend on the CNT contents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 983–989, 2010

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The physical and chemical interactions existing between the two blend components, tetraglycidyl-4,4'-diaminodiphenylmethane (TGDDM) and Bisphenol A polycarbonate (PC), were investigated by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The homogeneous phase behavior, which was found to exist not only in the heated binary blends of TGDDM/PC with no curing agents but also in amine-cured blends, is believed to be a result of these special chemical links developed between the TGDDM epoxy and linear PC polymer molecules. Mechanisms of chemical reactions and the resulting links between these two components upon heating of the TGDDM/PC blends (in the absence of any curing agents) have been proposed and proven by experimental results.

The oppositely oriented lamellae in ridge and valley bands of ring-banded spherulites in biodegradable poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) interacting with amorphous poly(vinyl acetate) (PVAc) were examined using polarized-light optical, scanning electron, and atomic-force microscopy techniques (POM, SEM, AFM). Solvent-etching and fracturing were utilized for probing the interior morphology of the large-size ring-banded spherulites in PHBV/PVAc (70/30) blend [T(c) = 110 °C] films or thick bulk of various thicknesses. SEM analysis revealed that dual ridges of two opposite-oriented lamellae correspond to two-color bands (yellow and blue) of successive rings in POM micrographs. Fracture of thick blend samples further exposed that interior 3D spherulites were composed of sheath-kebab (similar to corrugated board) lamellae of two mutually perpendicular orientations.