A series of regular alternating terpolymers of ethene and propene with carbon monoxide with different Et/CO content was characterized by wide- and small-angle x-ray scattering, differential scanning calorimetry, and diamagnetic susceptibility measurements. All terpolymers proved to be amorphous at room temperature. The occurrence of multiple endothermic effects appearing at Tm, above the glass transition temperature Tg, and extending over a fairly broad temperature range is discussed on the basis of a three-dimensional network of Et/CO nanocrystals spanning the continuous, noncrystalline Pr/CO matrix in the initial samples. Magnetic susceptibility data obtained over the temperature range studied confirm our previous findings: accordingly, it is the onset of large-scale (segmental) mobility, rather than density variations, that is responsible for the discontinuous changes of diamagnetic susceptibility observed, at Tg and Tm. The unusual large differences found between absolute χ-values for samples with different chain composition are interpreted in light of the classical theory of random copolymerization, assuming that terpolymer chains are made up of two randomly distributed "virtual comonomers," (Et/CO) and (Pr/CO).

10 pags., 4 figs.