Multilayer coextrusion of rubber compounds

Abstract

This research work presents the first continuous multilayer coextrusion system for high viscosity elastomeric materials. Three unvulcanized rubber materials were chosen to validate the system: two butyl rubbers and a polyisoprene. The elastomers were characterized under oscillatory shear and the results used to perform computational flow simulations to investigate the effect of geometry on the flow path and flow rate. Successful extrudates of 8 and 32 layers were extruded at two different throughput rates for rheologically matched and rheologically mismatched material pairs. The results show good layering performance for both systems with little existence of viscous encapsulation and acceptable pressure drops. Computational and experimental results both show a nonuniform layer thickness distribution due to the geometric design of the layer multiplier extrusion dies, which were designed to minimize pressure drop in the system. This nonuniformity decreases with increasing number of layers. POLYM. ENG. SCI., 55:1520-1527, 2015

Layer multiplication co‐extrusion of cross‐linked polymer microsphere‐filled systems

“…This technique has shown to be effective in achieving increased property performance in areas of barrier, [1][2][3] insulation, [4][5][6] mechanical, [7][8][9] optical, etc. [10][11][12] The technology has been expanded to include the co-extrusion of polymers into tubing with a high layer number. [13][14][15][16][17] Additionally, work has been conducted in examining filled polymer systems as layer components.…”

“…Layer multiplication co‐extrusion (LMCE) has been widely used to achieve high numbers (100 s–1000 s) of very thin layers with the use of a limited number of extruders. This technique has shown to be effective in achieving increased property performance in areas of barrier, 1–3 insulation, 4–6 mechanical, 7–9 optical, etc 10–12 . The technology has been expanded to include the co‐extrusion of polymers into tubing with a high layer number 13–17 .…”

Theoretical and experimental study on three‐layered polymeric balloon catheter processing

“…Bian and Jin [19] also investigated the temperature effect and obtained the optimal temperature range of 110 C to 150 C for balloon catheter fabrication. Harris et al [20] investigated the multimaterial coextrusion process by both experimental studies and numerical simulations. They found that the wall thickness of each layer was nonuniform and it was necessary to minimize the pressure drop by optimizing the structural parameters of the coextrusion die.…”