Small molecule additives are used in melt processing, sometimes to lubricate extrusion or to provide bespoke hydrophilic surfaces. Both applications require the additive to migrate to the film surface during or shortly after extrusion, which is often challenging and rarely efficient. We are studying this process for a model amphiphilic additive which migrates to LDPE surfaces rendering them more hydrophilic. In this present experiment, we want to better understand the role of process temperature & crystallinity on surface segregation. Neutron reflection is the only method to determine surface segregation of the additive in the melt state. We will use this technique to determine melt segregation to compare to the segregation which we use on semicrystalline (below Tm) state. Ultimately we will feed results into theory and computational models to provide a toolkit to predict migration