The effect of polyolefin extensional rheology on non-isothermal film blowing process stability

Effect of die exit stress state, Deborah number, uniaxial and planar extensional rheology on the neck-in phenomenon in polymeric flat film production

“…In the first step, deformation rate dependent 'steady state' uniaxial extensional viscosity data (taken from the transient viscosity data peaks for given deformation rates, [60] and [69])…”

“…In this article, as a part of circumstantial set of our studies on the free-surface flow instabilities [58][59][60], the effect of die exit stress state, extensional rheology and Deborah number on the neck-in phenomenon is systematically investigated via viscoelastic isothermal modeling (utilizing 1D membrane model coupled with a single-mode modified Leonov model) and obtained results are compared with suitable literature experimental data.…”

Evaluation of Thermally Induced Degradation of Branched Polypropylene by Using Rheology and Different Constitutive Equations

“…For the pure shear flow, the function f ( I |D| , II D , III D ) becomes equal to 1 and thus, the viscosity becomes a function of second invariant of deformation rate tensor D (IID=sans-serifγ˙2) only. In the pure uniaxial extensional flow, where I|D|= 2trueε˙, IID=3sans-serifε˙2, and IIID=sans-serifε˙3/4, the function f ( I |D| , II D , III D ) becomes nonzero and model becomes capable of representing steady-state extensional flows for different polymer melts [69,70,71,72,73,74].…”

Investigation of convective heat transfer in 9-layer film blowing process by using variational principles

“…This model was chosen in this work because it provides analytical expression for the bubble shape, utilizes small number of physical parameters, is able to describe experimental film blowing data for variety of polymers and processing conditions and was successfully used in the film blowing stability analyses [2,[44][45][46][47]. Note that even if the principle of stationary potential energy approach, widely used in the mechanics of deformable solids, can Table 1 Parameters A and / for different bubble shapes (y) (adapted from [43]).…”

“…also be useful for the basic understanding of the film blowing stability via variational principle based model as shown in [45,46], the study is not complete without some attention to stability in the dynamic sense [48,49]. It also should be mentioned that the utilized Zatloukal-Vlcek model is simple, but at the cost of having a limited ability to examine advanced constitutive relations and the microstructural relations.…”