The Problem of Die Drool in the Extrusion of Recycled Polyethylene

Present understanding of the formation of die drool is reported in light of current developments in materials for blown film polyethylene (PE). Two series of samples were collected from a blown film line, and the material from the die drool and the die channel, or blown film, were analysed separately. The techniques used included thermal analysis, melt rheology, filtration of dissolved material, and X-ray diffraction. Die drool was found to consist of segregated material, with the segregation depending on the content of high-molecular-weight branched polyethylene or impurities. As the presence of these PE materials may increase, it might be advisable for processors of recycled PE film to take prior actions to limit problems.