Thermal phase transitions of carbon monoxide-ethylene alternating copolymer: An FT/IR study

In this study an analysis of the changes that occur in the infared spectrum of the ethylene-carbon monoxide alternating copolymer as a function of the temperature is presented. This copolymer can assume two polymorphic crystalline states, named POK-alpha and POK-beta. Fourier transform infrared spectroscopy seems to be a good technique to observe the transition between these two forms, which occurs between 120 and 140 degrees C in an undrawn sample. The IR results have been supported by differential scanning calorimetry measurements. The data obtained have, also, clarified that in the solid state the structure of the ethylene-carbon monoxide copolymer is extended by strong intermolecular interactions that weaken its intrinsic resistance and aid its thermal degradation. These interactions are absent or at least less strong in the melt or in the amorphous state. (C) 1997 by John Wiley & Sons, Ltd.