Die swell is a phenomenon directly related to entropy and the relaxation of the polymer within the flow stream. Initially, a flow stream has a constant rate before entering the die, and the polymers within the stream occupy a roughly spherical conformation, maximizing entropy.

Nov 17, 2011 · When a viscoelastic fluid flows out of a die, the extrudate diameter is usually greater than the channel size. This is called die-swell, extrudate swell or the Barus effect. The degree of extrudate swell is usually expressed by the die-swell ratio (B) of extrudate diameter versus die diameter.

Die swell is a complex rheological phenomenon [1]. It can be observed as an extrudate with a cross-section (D ex) which is greater than the die cross-section (Do)' This effect, also known as extrudate swell, Barus effect, or % memory, is defined as the ratio Dex/DO = B and is a feature of polymer melt flow.

Jul 5, 2023 · The die-swell increases as a function of the volumetric flow rate and shear stress but decreases as a function of the hot end temperature setpoint and nozzle orifice diameter. For modelling, an implementation of the Tanner model for die-swell displays good agreement with experimental results.

Swelling of an extrudate, on emerging from the die, is a die swell. Why die swell occurs? Extrusion dies have a converging section and a parallel section (die land). Extensional flow, causing stretching due to reduction In cross sectional area in the converging section.

This effect, also known as extrudate swell, Barus effect, or % memory, is defined as the ratio D ex /D 0 = B and is a feature of polymer melt flow. Die swell is associated with the viscoelastic nature of polymer melts as it exceeds the swelling of constant viscosity (Newtonian) fluids.

Why do polymers show die swell behavior, how to calculate die swell and how to minimized die swell is explained in this video. Die swell demonstration.For bu...

Feb 13, 2025 · What is Die Swell? When a polymer is pushed through a spinneret (a tool with small holes) under pressure, part of the energy helps the polymer flow, while some is stored as elastic energy. After the polymer exits the spinneret, the stored elastic energy is released, causing the polymer to expand or “swell.”

Mar 1, 1978 · Highly viscous elastic fluids, such as polymer melts, exhibit a far greater increase, sometimes between 200 and 300%. This phenomenon is often referred to as ″Barus effect″ or ″die swell″ and is...

nal shape and attempts to return to it. Die swell can result in an extrudate with several times the diameter of the die, . chieved using a compounder or extruder. Materials are fed, in powder or pellet form into the extruder, melted, mixed and transported to the die where the blend is extruded, whereupon the sw.