Changing morphological features in a semi-crystalline polymer in material-extrusion based additive manufacturing

Research output: Chapter in Book/Report/Conference proceedingConference contribution

External Organisational units

  • Department of Materials Science and Engineering, Ghent University
  • Research Center Pharmaceutical Engineering GmbH

Abstract

Despite the high proportion of research activities in the field of material-extrusion based additive manufacturing, this technology still faces major challenges. In particular, when 3D printing with semi-crystalline polymers, a variety of process-related morphological and crystallographic changes can occur apart from general problems such as shrink-age and warpage. The complex relationships between the material, its processing and the final properties are still not fully understood. Hence, the influence of process-related orientations on the morphology and material properties of 3D-printed polypropylene (PP) was analysed by polarisation microscopy, wide-angle X-ray scattering, dynamic dif-ferential calorimetry, thermomechanical analysis, thermal conductivity measurements and "trouser tear" tests. By vary-ing two standard process parameters, four sample types with a completely different property portfolio with regard to morphology were generated. Low (200 °C and 2.25 mm/s) and high (250 °C and 22.5 mm/s) parameter settings for nozzle temperature and printing speed were investigated. Through in-depth analyses of four parameter sets, new in-sights into the formation of complex crystalline structures in 3D-printed semi-crystalline polymers are offered. It shows that minor changes of the printing parameters can have a great influence on the resulting material properties in different length scales. For example, for a high nozzle temperature in combination with a high printing speed layers with changing spherulite size were found. This finding could be correlated with the printing sequence of the slicer software, which confirms that the printing sequence proposed by the slicer software should not be chosen arbitrarily, but can be used to control the morphology and thus the mechanical properties of 3D-printed semi-crystalline poly-mers. Therefore, when handling semi-crystalline polymers such as PP, the characterisation of process-related morphological changes is particularly important and should never be neglected for future product developments.

Details

Original languageEnglish
Title of host publicationBook of Abstracts Polymer Meeting 14
Place of PublicationTU Graz
Publication statusPublished - 30 Aug 2021
EventPolymer Meeting 14 - TU Graz, Graz, Austria
Duration: 30 Aug 20212 Sep 2021
https://www.tugraz.at/events/pm14
http://www.pm14.tugraz.at

Conference

ConferencePolymer Meeting 14
CountryAustria
CityGraz
Period30/08/212/09/21
Internet address