Multi-layer co-extrusion blow molding

Abstract Multi-layer co-extrusion via the layer multiplication technique and a blow-molding set-up were used to produce bottles with a 129-layered structure of a model system of alternating polystyrene (PS) and poly (methyl methacrylate) (PMMA) layers. This method shows layer retention and thickness control with the use of melt rotation during the extrusion process. Samples were extruded and deformed angularly at different rotation speeds, blow-molded into bottles, and the overall wall thickness and analysis of individual layer thicknesses were performed. Angular rotation leads to weld line deformation and a change in layer thickness above a critical rotation speed in which the weld lines, inherited in the extrusion of the tube structures, are suitably deformed helically leading to uniform deformation during the blowing process. This method has potentially large implications for single cavity blow molding processes where high-performance properties, e.g., high barrier, insulation, mechanical, are of upmost importance, potential industries include gas transport, specialty packaging, and medical.