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Aging behavior of thermoplastic elastomers in the laser sintering process

Published online by Cambridge University Press:  19 August 2014

Stefan Ziegelmeier ,
Frank Wöllecke ,
Christopher J. Tuck ,
Ruth D. Goodridge  and
Richard J.M. Hague
Stefan Ziegelmeier*
Affiliation:
Rapid Technologies Center, BMW Group, Munich, Bavaria 80788, Germany; and Additive Manufacturing and 3D Printing Research Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, United Kingdom
Frank Wöllecke
Affiliation:
Rapid Technologies Center, BMW Group, Munich, Bavaria 80788, Germany
Christopher J. Tuck
Affiliation:
Additive Manufacturing and 3D Printing Research Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, United Kingdom
Ruth D. Goodridge
Affiliation:
Additive Manufacturing and 3D Printing Research Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, United Kingdom
Richard J.M. Hague
Affiliation:
Additive Manufacturing and 3D Printing Research Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, United Kingdom
*
a) Address all correspondence to this author. e-mail: stefan.ziegelmeier@bmw.de
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Abstract

It is known that polymers used in laser sintering (LS) change their intrinsic properties due to processing conditions that are close to the crystalline melting temperature. This paper evaluates the aging behavior of a thermoplastic polyurethane powder, comparing with to a commercially available LS elastomeric material (Duraform®Flex, 3D Systems). To represent a realistic production environment, the materials were aged during 14 processing cycles in the LS process without refreshing with virgin material. Following each aging cycle, both the powder and the sintered parts were examined for chemical and physical aging effects. The results showed that the materials observed could be used without refreshing throughout the 14 aging stages, however, changes in the processing behavior as well as in the parts' mechanical properties were evident. These changes were due to the differing aging states of the LS-powder showing an increase in the particle size affecting the bulk materials packing density. Modifications in the rheological properties can be seen in a decrease of molecular weight likely to reduce the mechanical strength of tensile specimens.

Keywords

polymerthermoplastic polyurethanepowder processingthermal stresseslaser sinteringflow propertiesbulk behavior

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Type
Articles
Information
Journal of Materials Research , Volume 29 , Issue 17: Focus Issue: The Materials Science of Additive Manufacturing , 14 September 2014 , pp. 1841 - 1851
Copyright
Copyright © Materials Research Society 2014 

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