Analysis of entrance pressure drop techniques for extensional viscosity determination

Self Cite

Abstract. In this work, novel rectangle and circular orifice dies have been utilized for temperature-strain rate dependent planar and uniaxial elongational viscosity measurements for the LDPE polymer melt by using standard twin bore capillary rheometer and Cogswell model and the capability of three different constitutive equations (novel generalized Newtonian model, modified White-Metzner model, modified Leonov model) to describe the measured experimental data has been tested. It has been shown that chain branching causes the strain hardening occurrence in both, unixial and planar elongational viscosities and its maximum is shifted to the higher strain rates if the temperature is increased. The level of uniaxial elongational strain hardening for the branched LDPE sample has been found to be higher in comparison with the planar elongational viscosity within wide range of temperatures.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of temperature-strain rate dependent uniaxial and planar elongational viscosities for branched LDPE polymer melt

Zatloukal

2013

Self Cite

“…[7][8] leads to much precise evaluation of index of non-Newtonian behaviour, there is still tendency to artificially overestimate and underestimate index of non-Newtonian behaviour at low and high deformation rates, respectively, having impact especially on extensional viscosity, as visible in Figure 7. Therefore it can be concluded that the specific care has to be paid during approximation function selection for the index of non-Newtonian behaviour determination and physical rather than unphysical polynomial functions should be preferred.…”

Section: Effect Of Approximation Function Type Selection On the Indexmentioning

confidence: 99%

Rheological evaluation of melt blown polymer melt

Drábek¹,

Zatloukal²

2013

Self Cite

“…In order to determine uniaxial extensional viscosities at very high extensional strain rates, the Cogswell model [10] has been utilized. In order to measure entrance pressure drop correctly, recently proposed zero length die has been used [11]. Transient uniaxial extensional viscosity was measured using the ARES 2000 rheometer equipped with the SER Universal Testing Platform (SER-HV-A01 model) from Xpansion Instruments [12][13] at two different extensional strain rates (1 s -1 and 10 s -1 ).…”

Section: Experimental Analysismentioning

confidence: 99%

Effect of Fluoropolymer Antidripping Agent on Rheological Behavior of LLDPE

Obr¹,

Zatloukal²

2011

Self Cite

Abstract. In this work, high molecular weight polytetrafluoroethylene based antidripping agent was blended with Ziegler-Natta based LLDPE in different concentrations. Rheological characterization was consequently performed for all the blends and the obtained results were compared with the pure LLDPE. It has been found that high molecular weight PTFE based melt modifier MM 5935 EF significantly enhancing the shear viscosity/elasticity and especially the extensional viscosity of the LLDPE melt.