Via extensional rheometry

When an alternating stack of molten polymer sheets is pulled in uniaxial tension parallel to the layers, interfacial area per unit volume increases, amplifying interfacial effects. To investigate these effects in multilayer samples, a reactive pair of polyethylene was co-extruded to give a layered structure (256 layers). Interfacial stress of the sample was, studied through extensional rheometry at different extension rates: and residence times. The results clearly showed that stress acting on the interfacial layer (parallel to the stretching direction) had strong extension rate and residence time dependence, and affected the extensional force of the multilayer sample.