Adapting a Capillary Rheometer for Research on Polymer Melt Interfaces

Abstract

Interfaces between immiscible polymers are widely known to be the origin of premature failure in multilayers and blends. Developing a small-scale, continuous method to fabricate interfaces from polymer melts with short contact times to simulate industrial coextrusion is critical for assessing new materials, polymeric systems, and processing conditions. Here we develop a miniature coextrusion die that can be fitted to a twin bore capillary rheometer for precise temperature and contact time control from 4.4 to 440 s. The design of the feedblock, stacker, manifold, and land zones was optimized via flow simulation software to allow bilayer coextrusion with minimal (<10%) edge distortions. Bilayer films of isotactic polypropylene (iPP) and polyethylene (PE) were produced using 90% less material than a lab-scale continuous multilayer coextrusion device, and the interfacial adhesion was in excellent agreement with iPP/PE bilayers produced using a continuous coextrusion technique for a range of PE molecular archi...