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Thomas Rundqvist. Fotograf Johan Persson.

Thomas Rundqvist

Innovation developer

Thomas Rundqvist. Fotograf Johan Persson.

Development of a Novel Method for Evaluation of Interfacial Tension between Polymer Melts


  • Thomas Rundqvist

Summary, in English

A novel method for the evaluation of interfacial tension of high viscosity polymer melts is described. The method involves the tracking of the shape evolution of a highly deformed droplet of one material imbedded in a second one. This makes it possible to determine the interfacial tension over a relatively short time period. The imbedded material is initially either a fiber or a disk. The technique of preparing the samples makes it possible to measure on practically any combination of polymer melts without restrictions on viscosities and melting temperature, as long as one of the materials is transparent in the molten state.

The retraction of the disk is observed by using a microscope with a high resolution video camera connected to a personal computer. Data of the retraction is acquired by using an image analysis software, measuring the dimensions of the imbedded material.

The driving force for the shape evolution is interfacial tension and it is balanced by viscous forces. The analysis of the retraction process is done analytically with a simplified one dimensional model. The model is compared to experiments with the polymers PS/PMMA at 210°C, covering viscosity ratios over a range of six decades. It is shown that interfacial tension can be determined over the whole range and a value of 1.1 ± 0.3 mN/m was obtained for all samples.

PS/PMMA is also studied in the temperature range 150-250°C where the interfacial tension is found to be 3.6 - 0.012 (T - 273) mN/m, where T is the temperature in K. Viscosities were in the range from 10^2 to 10^6 Pa s.

Further, the interfacial tension is measured between PP/PA, PP/PBT, and PP/LCP. For these blends the effect of reactive compatibilizers on the interfacial tension is evaluated. The interfacial tension is found to decrease with the addition of the compatibilizer. The measured interfacial correlates well with the morphology of the blends.


  • LU Innovation

Publishing year




Document type



Department of Production and Materials Engineering, LTH, Lund University,


  • Materials Engineering


  • Polymer technology
  • Polymer Blends
  • Imbedded Fiber
  • Imbedded Disk
  • High viscosity
  • Interfacial tension
  • Polymer melts
  • biopolymers
  • Polymerteknik




  • [unknown] [unknown]


  • ISRN: LUTMDN/(TMMV-1031)/1-55/(1997)

Defence date

7 May 1997

Defence time


Defence place

Room M:B, Lund Institute of Technology, Lund University


  • Andrew N. Hrymak (Professor)