On the "viscosity maximum" during the uniaxial extension of a low density polyethylene

Details On the "viscosity maximum" during the uniaxial extension of a low density polyethylene On the "viscosity maximum" during the uniaxial extension of a low density polyethylene

2010-01-13

arxiv.org/abs/1001.2093v1

Physics

Condensed Matter

Soft Condensed Matter

Scientific paper

An experimental investigation of the viscosity overshoot phenomenon observed during uniaxial extension of a low density polyethylene is pre- sented. For this purpose, traditional integral viscosity measurements on a Muenstedt type extensional rheometer are combined with local mea- surements based on the in-situ visualization of the sample under exten- sion. For elongational experiments at constant strain rates within a wide range of Weissenberg numbers (Wi), three distinct deformation regimes are identified. Corresponding to low values of Wi (regime I), the tensile stress displays a broad maximum. This maximum can be explained by simple mathematical arguments as a result of low deformation rates and it should not be confused with the viscosity overshoot phenomenon. Corre- sponding to intermediate values of Wi (regime II), a local maximum of the integral extensional viscosity is systematically observed. However, within this regime, the local viscosity measurements reveal no maximum, but a plateau. Careful inspection of the images of samples within this regime shows that, corresponding to the maximum of the integral viscosity, sec- ondary necks develop along the sample. The emergence of a maximum of the integral elongational viscosity is thus related to the distinct in- homogeneity of deformation states and is not related to the rheological properties of the material. In the fast stretching limit (high Wi, regime III), the overall geometric uniformity of the sample is well preserved, no secondary necks are observed and both the integral and the local transient elongational viscosity show no maximum. A detailed comparison of the experimental findings with results from literature is presented.

Affiliated with

Also associated with

No associations

Rating

On the "viscosity maximum" during the uniaxial extension of a low density polyethylene does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with On the "viscosity maximum" during the uniaxial extension of a low density polyethylene, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the "viscosity maximum" during the uniaxial extension of a low density polyethylene will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-524956