Collect. Czech. Chem. Commun. 1995, 60, 1733-1740

Flow-Induced Crystallization of High-Density Polyethylene

Ivan Fortelný, Jana Kovářová and Josef Kovář

Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6, Czech Republic


Crystallization induced by flow in the capillary viscometer was studied for four grades of linear polyethylene. From rheological and DSC measurements it follows that crystallization was induced in all samples under study at temperatures higher than melting temperatures of the same samples crystallized at rest. The maximum temperature of flow-induced crystallization increases with increasing molar mass of polyethylene. Flow-induced crystallization of injection moulding grades of polyethylene only takes place in a limited interval of shear rates. This effect is explained as a consequence of the shear rate distribution in the capillary.