A model for the rheotens experiment is proposed to probe extensional rheology of polymer melts relevant to fabrication. The philosophy of the model is the coupling of the filament transport phenomena equations with kinetic theory constitutive equations of the differential type. A modified Giesekus (MG) constitutive equation seems to outperform other constitutive equations of the kinetic theory type, such as original Giesekus (OG) and finitely extensible non-linear elastic (FENE)-like, in terms of fitting and predictive capability of force rheotens curves at different process conditions for (i) substantially linear homogeneously branched polymers (AFFINITY (TM) polyolefin plastomers), (ii) linear low density polyethylene (LLDPE) (ASPUN (TM) fiber grade resins) and (iii) dow LDPE melts, with a variety of melt indexes and polydispersities (M-w/M-n). The model is a useful tool for estimation of an apparent elongational viscosity versus strain rate curve from raw rheotens data. It predicts a dominating extension thinning behavior for both melts of AFFINITY and ASPUN. For LDPE, the model predicts a pronounced strain hardening effect with a maximum in the elongational viscosity at a certain strain rate followed by extension thinning, behavior consistent with long chain branched melts. The MG rheotens model naturally predicts a smooth elongational viscosity curve with no singularity in its slope, which is a potential advantage relative to previous modeling approaches. (c) 2006 The Society of Rheology.