Flow-Induced Crystallization of High-Density Polyethylene

1995 ◽  
Vol 60 (10) ◽  
pp. 1733-1740 ◽  
Author(s):  
Ivan Fortelný ◽  
Jana Kovářová ◽  
Josef Kovář
Keyword(s):  
High Density Polyethylene ◽  
Molar Mass ◽  
Maximum Temperature ◽  
Capillary Viscometer ◽  
Linear Polyethylene ◽  
Shear Rates ◽  
Melting Temperatures ◽  
Dsc Measurements ◽  
Induced Crystallization ◽  
Flow Induced Crystallization

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.

Effect of Gel and Nonrubber Constituents on the Extrusion Properties of Guayule Rubber

1983 ◽  
Vol 56 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Sergio A. Montes ◽  
M. A. Ponce-Vélez
Keyword(s):  
Experimental Study ◽  
Shear Rates ◽  
Paraffinic Oil ◽  
Induced Crystallization ◽  
Flow Induced Crystallization ◽  
Low Shear

Abstract An experimental study on the effect of gel and nonrubber constituents on the extrusion behavior of guayule rubber (GR) has been carried out. At 140°C, gel increases the viscosity at low shear rates. When GR is properly stabilized, no peptizing effect is imparted by the resin. However, the resin acts as a moderate plasticizer as compared to paraffinic oil. At 120°C, the effect of gel is noticeable at high extrusion rates, increasing the viscosity, suggesting an increase in the tendency for the occurrence of flow-induced crystallization.

scholarly journals Development of Inorganic Particle-Filled Polypropylene/High Density Polyethylene Membranes via Multilayer Co-Extrusion and Stretching

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 306
Author(s):  
Pilar Castejón ◽  
Marcelo Antunes ◽  
David Arencón
Keyword(s):  
Calcium Carbonate ◽  
High Density Polyethylene ◽  
High Density ◽  
Porous Membranes ◽  
Inorganic Particle ◽  
Porous Surfaces ◽  
Mineral Fillers ◽  
Induced Crystallization ◽  
Thermal Stability Of ◽  
Flow Induced Crystallization

This work is made to ascertain the effects of mineral fillers, namely calcium carbonate and talc, on the morphology and properties of multilayer polypropylene (PP)/high-density polyethylene (HDPE) porous membranes. Multilayer membranes were prepared using the three-stage Melt-Extrusion, Annealing and Uniaxial Stretching (MEAUS) process. The orientation of PP’s crystalline phase was affected by both the flow-induced crystallization and the heterogeneous nucleation promoted by the fillers. A synergistic effect was observed in the filled samples due to the generation of pores after the stretching-induced lamellae separation and the debonding of mineral fillers from the polymeric matrix. The fillers increased the porous surface, leading to an increase of permeance to air, being this effect more marked at higher filler contents. Talc showed a higher efficiency to create porous surfaces when compared to calcium carbonate. The thermal stability of the membranes increased with filler addition, as well as their stiffness and strength.

Modeling flow-induced crystallization in isotactic polypropylene at high shear rates

2015 ◽  
Vol 59 (3) ◽  
pp. 613-642 ◽  
Author(s):  
Peter C. Roozemond ◽  
Martin van Drongelen ◽  
Zhe Ma ◽  
Martien A. Hulsen ◽  
Gerrit W. M. Peters
Keyword(s):  
Isotactic Polypropylene ◽  
High Shear ◽  
Shear Rates ◽  
High Shear Rates ◽  
Induced Crystallization ◽  
Modeling Flow ◽  
Flow Induced Crystallization
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