Industrially applied rubber compounds consist of several reinforcing fillers such as silica and carbon black preventing the use of many popular flow visualization techniques. Consequently, only few studies have reported on the flow behavior of rubbers leaving open questions regarding the contraction flow behavior of these highly filled polymer systems. However, experimental data and a precise numerical description is fundamentally important for designing and optimizing extrusion dies, cold runners and complex injection molding tools. First, a series of tests was carried out investigating the axisymmetric entry flow for a contraction ratio of 12:1. Using a high-pressure capillary rheometer (HPCR) the influence of the length to diameter (L/D) ratio, piston speed and die geometry was analyzed for several different rubber compounds. Second, extrusion based experiments were pursued varying the inlet die angle from 180° to 60° and the extrusion time up to 40 minutes. No inlet vortices were observed for neither experimental setup, but dead zones for inlet angles > 90°. Finally, the linear and non-linear viscoelastic material behavior of a co-extruded SBR rubber compound was determined over a wide frequency and temperature range. Flow simulation results using integral (K-BKZ/PSM) rheological constitutive equations correlate well with experimental data proving its applicability for optimizing complex tool geometries of the rubber processing industry.
|Publication status||Published - 18 Nov 2019|
|Event||PPS Europe-Africa 2019 - Pretoria, South Africa|
Duration: 18 Nov 2019 → 21 Nov 2019
|Conference||PPS Europe-Africa 2019|
|Period||18/11/19 → 21/11/19|