The Intermittent Dormancy of Ethylene Polymerization with the Assistance of Nitrogen Microbubbles

The inert nitrogen microbubbles are incorporated during ethylene slurry polymerization to retard the formation of chain entanglements through the intermittent dormancy of living polymer chains. This dormancy effect is endowed by the highly frequent and intensive collisions of countless microbubbles on the growing polyethylene particles, which blocks the transfer channel of reactants on the particle surface. It is evidenced that the transfer barrier slows down the chain propagation and provides extra time for the propagated chains to be crystallized. Thus, the nascent polyethylene with the reduced entanglements and a considerable amount of monoclinic lamellae is achieved by the catalyst with the original ability to synthesize the highly entangled polyethylene. The synchronous increment of stiffness, toughness, and strength is found for the synthesized polyethylene owing to the reduced chain entanglements.