Measuring Flow-Induced Crystallization Kinetics of Polyethylene after Processing

• DOI: 10.1021/acs.macromol.0c02477
• Publication Date: 2021-02-15T22:34:29Z
• Authors: Kenneth L. Kearns; Justin Scherzer; Marius Chyasnavic...; Daria Monaenkova; Jonathan Moore; Robert L. Sammler; Tom Fielitz; David A. Nicholson; Marat Andreev; Gregory C. Rutledge
• Keywords: Linear low-density polyethylene; Isothermal process; Shearing (physics)

The flow-induced crystallization of polymers is a ubiquitous aspect processing where the effect flow can dramatically alter end-use properties polymers. Here, we will describe development new methodology whereby on kinetics in polyethylene be determined after has occurred. This first illustration for rapidly crystallizing polyethylene, which required different approach than what been done other materials. Critically, this necessitated an understanding self-nucleation and melt memory behavior as well using thermal contact fluids with low kinematic viscosity. With optimized protocol, linear low-density LLDPE, heated to temperatures just above melting point crystals fast-scanning calorimetry, history maintained even melt. As result, polymer melted many times without significantly changing kinetics, enables measurement over wide range isothermal temperatures. We demonstrate ability measure enhancement samples sheared parallel-plate rheometer or fabricated blown film. For LLDPE studied here, were four faster, relative quiescent crystallization, prepared at highest shearing rates. shear rate decreased, decreased. A particularly powerful developed that it also used as-made parts, report twofold films manufactured pilot-scale blown-film line.