Case Study: Using LAOS to Investigate Extrusion Instability

In this video we explore a client that introduced new raw elastomers into its compounds as low-cost alternatives to the elastomers they had been using. However, compounds made with these new elastomers exhibited severe extrusion instability. To investigate the issue, we applied Large Amplitude Oscillatory Shear (LAOS) rheology to assess the presence of long chain branching (LCB) in these elastomers. The presence of long chain branching in a polymer has a large impact on his viscoelastic properties and can affect significantly the processability of filled rubber compound: black incorporation time, die swell, extrusion behavior. For instance, the incorporation of long chain branches has been used in EPDM and polyethylene (PE) to enhance shear thinning/flow behavior and, in the case of PEs, to delay the onset of melt fracture toward higher shear rates. You can learn more about LAOS in this blog series from Alpha: https://tinyurl.com/2n6earsp Watch the case study video to see how we used the data from the LAOS testing to assess the low-cost elastomers and explain the extrusion instability.