The effect of synthetic conditions on the structure and properties of alternating terpolymers of ethylene, propylene, and carbon monoxide

The effect of the conditions of synthesis on structure and mechanical and thermal properties is studied for thermoplastic elastomers based on terpolymers of ethylene, propylene, and carbon monoxide. Samples synthesized at a preset concentration of the monomers in an autoclave are characterized by a microblock structure and contain crystallites of distorted β form of poly(ethylene ketone) and triclinic modification of poly(propylene ketone). The use of a new method of synthesis based on the pulse feeding of ethylene significantly reduces the blockiness of the polymer chain. Terpolymers with an ethylene content of about 40% thus prepared are characterized by low crystallinity (below 10%) and the absence of the crystalline phase of poly(ethylene ketone). The tensile drawing of such samples leads to the development of an ordered structure whose parameters are close to those of the orthorhombic crystal lattice of the poly(propylene ketone) copolymer. The formed crystalline domains serve as a physical entanglement network and impart good elastomeric properties to the resultant material.