Stretching calorimetry and X-ray characterization of deformational behavior of new high molecular weight propene-carbon monoxide alternating co- and terpolymers

Structure, properties, and deformation behavior of a high molecular weight propene-CO alternating copolymer (ElPCO 200) and ethene-CO/propene-CO terpolymers (EPEC 1; E-CO = 47% and EPEC 2; E-CO = 69%) were investigated. The terpolymer with high molar ratio of ethene-CO to propene-CO (EPEC 2) is a typical thermoplastic and reveals relatively high crystallinity, while the terpolymer of lower content of ethene-CO groups (EPEC 1) and the propene-CO copolymer (ElPCO 200) exhibit elastomeric behavior. In spite of the possible random stereo- and regioregularity, the propene-CO chains crystallize with regular 3/1 chain conformation. According to X-ray data the synthesized terpolymers consist of blocks of propene-CO segments and blocks enriched with ethene-CO groups. The main structural changes at deformation were studied by means of X-ray diffraction and deformation calorimetry. It is established that the large reversible deformation of the samples studied is determined mostly by the amorphous regions. Deformation calorimetry results, treated according to the modern theory of thermoelasticty of rubber-like materials, showed that the energy contribution (ΔU/W)_V,T and the temperature coefficient of the unperturbed dimension of chains d In〈r²〉₀/dT are more negative than for PE and PP, which seems quite reasonable owing to the chemical structure of the 1,4-polyketone macromolecules.