Optimierung von PLA/TPS Blends

Translated title of the contribution: Optimization of PLA / TPS blends

Martin Hirschenauer

Research output: ThesisMaster's Thesis


The aim of this master thesis was to optimize a blend of polylactic acid and thermoplastic starch for injection molding applications. Due to economic reasons the starch content should be as high as possible. This optimization focused on the formulation development and processing. As a basis for decision, the characteristic values determined from tensile tests and elongational rheology have been used. To verify the injection molding processability of the material, drinking cups were manufactured at an injection molding machine at Miraplast GmbH. To gain insight into the thermal behavior of the material a DSC test was made. To verify the suitability as a food contact material an overall migration test was made. By varying the PLA / TPS ratio and additive concentration, an optimal formula was developed. Therefore the additives Maleic Anhydride (MSA), Sorbitol and Citrofol were selected. MSA is used as a compatibilizer, Sorbitol as a plasticizers, and Citrofol as a softener. For the optimization of the processing parameters screw geometry, screw speed and temperature profile of the extruder were set as variables. In the course of formulation development, the additives MSA, Sorbitol and Citrofol were added in various proportions. DOE (Design of Experiments) experimental procedure showed that the mixing ratio of PLA and TPS had the strongest influence on the mechanical properties of the compound. Furthermore, a reinforcing effect of MSA as a compatibilizer was perceived. Next, the processing parameters were evaluated for their potential for optimization using a factorial experimental design. This was followed by the investigation of specified processing parameters for their potential for optimization again through a DOE test set-up. We found that the shear-input has the most significant impact on the homogeneity of the polymer mixture. However, a careful tuning of the parameters was required to obtain optimum results and to find a compromise between adequate mixing and incipient degradation of the material.
Translated title of the contributionOptimization of PLA / TPS blends
Original languageGerman
  • Kracalik, Milan, Co-Supervisor (internal)
  • Holzer, Clemens, Supervisor (internal)
Award date29 Jun 2012
Publication statusPublished - 2012

Bibliographical note

embargoed until null


  • PLA
  • TPS
  • optimization
  • compound
  • recipe optimization
  • injection moulding
  • machine parameters
  • overall migration

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