Interfacial Instabilities in Multilayer Extrusion

K. Ho, J.S. Lee, N. Viriyabanthorn, C. Sung, C.M.F. Barry and J.L. Mead
University of Massachusetts Lowell, US

Keywords: multilayer, interfacial instabilities, coextrusion, feedblock, AFM, layer multiplying element

Abstract:
Polymeric alternating multilayer laminates have been prepared by coextrusion, utilizing a specially designed feedblock to combine the two incoming materials from different extruder. Layer multiplying elements (LME) were used to split the melt stream, divide it, and then bring the two polymeric melt streams together, increasing the number of layers, while decreasing the thickness of each layer. Polycarbonate (PC) and polypropylene (PP) were extruded to form alternating structures by repeated layer multiplications. The materials were characterized by optical microscopy (OM) and atomic force microscopy (AFM) to study layer instabilities. Zig-zag type instabilities were found at the interfaces, predominantly in the center of the samples, which originated from the interfaces near the walls. Instabilities could be reduced by increasing the temperature of the LMEs and decreasing the total flow rate of both materials.

Nanotech 2004 Conference Technical Program Abstract