Rheological characterisation of a high-density polyethylene with a multi-mode differential viscoelastic model and numerical simulation of transient elongational recovery experiments

The rheological characterisation of a high-density polyethylene is performe d by means of measurements of the storage and loss moduli, the shear viscos ity and the transient uniaxial elongational viscosity, the latter being obt ained with the Meissner extensional rheometer. The rheological behaviour of the polymeric material is described by means of a multimode Phan Thien-Tan ner fluid model, the parameters of which are successively fitted on the bas is of the linear and non-linear properties. By using a semi-analytical tech nique and the finite element method, numerical investigations are performed for the shape recovery of the sample, and the predictions are compared wit h their experimental counterparts. Surface tension effects are also explore d. We discuss the agreement between the experiments and the simulation resu lts.