Extrusion Defects and Flow Instabilities of Molten Polymers

Abstract

International audienceWhen certain critical conditions are exceeded, the flow of a polymer melt becomes unstable, giving rise to particular phenomena that are the subject of this review. These instabilities are a vital industrial problem, as they are the key to productivity of extrusion processes. Indeed, their onset leads to unacceptable products and is thus the upper limit of the processing conditions. They are also a fascinating scientific problem because, although studied and discussed for more than half a century, they are still not fully understood and their mechanisms are still sometimes controversial. In the present literature review, we present an overview of the studies carried out for fifty years, as well as our own opinion on the underlying mechanisms.3-2

In Situ Surface Defect Detection in Polymer Tube Extrusion: AI-Based Real-Time Monitoring Approach

“…However, typical defects occur on the tubing surface during the extrusion of PFA tubes. As shown in Figure 1 b–d, the defects exhibit unique characteristics depending on their causes [ 18 , 19 , 20 ]. These defects can directly affect the manufacturing quality and durability of the PFA tubes [ 21 ].…”

Experimental separation of the onset of slip and sharkskin melt instabilities during the extrusion of silica-filled, styrene–butadiene rubber compounds

“…For general review articles about melt instabilities, we refer the reader to Agassant et al (2006) and Vergnes (2015). The focus of this work is on the occurrence of melt instabilities for SBR compounds, as they show different behavior during the extrusion process compared with the aforementioned plastics.…”

Volume instabilities in capillary flow of pure SBR and SBR compounds

“…In the tire industry, the production rate of treads in extrusion process is often limited by the onset of volume instabilities, which are known in the literature as the general term of "gross melt fracture". If the extrusion defects are now well known and correctly understood for the molten polymers [1][2][3], this is not the case for elastomer compounds, for which the publications are more rare. There is much literature on the rheological behavior of pure elastomers including in-depth studies on flow instabilities.…”