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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
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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References

REFERENCES

ASTM International: ASTM 29211-11e3, Standard Terminology for Additive Manufacturing—Coordinate Systems and Test Methodologies (ASTM International, West Conshohocken, PA, 2011).Google Scholar
Kruth, J.P., Levy, G., Klocke, F., and Childs, T.H.C.: Consolidation phenomena in laser and powder-bed based layered manufacturing. CIRP Ann.-Manuf. Technol. 56(2), 730 (2007).Google Scholar
Wohlers, T. and Caffrey, T.: Wohlers Report 2013 (Wohlers Associates, Inc., Fort Collins, CO, 2013).Google Scholar
Schmid, M., Amado, A., and Levy, G.: iCoPP - A new polyolefin for additive manufacturing (SLS). In Proceedings of the International Conference on Additive Manufacturing, Session 7 (Loughborough University, Loughborough, UK, 2011).Google Scholar
Goodridge, R.D., Tuck, C.J., and Hague, R.J.M.: Laser sintering of polyamides and other polymers. Prog. Mater. Sci. 57(2), 229 (2011).Google Scholar
Diller, T.T., Yuan, M.M., Bourell, D.L., and Beaman, J.J.: Thermal characterization of laser sintering of nylon-12. In International Conference on Advanced Research and Rapid Prototyping, Innovative Developments in Virtual and Physical Prototyping (Taylor & Francis Group, London, 2011), pp. 369.Google Scholar
Gornet, T.J., Davis, K.R., Starr, T.L., and Mulloy, K.M.: Characterisation of selective laser sintering materials to determine process stability.In Proceedings of the Solid Freeform Fabrication Symposium (University of Texas at Austin, Austin, TX, 2002), p. 8.Google Scholar
Dotchev, K. and Yusoff, W.: Recycling of polyamide 12 based powders in the laser sintering process. Rapid Prototyping J. 15(3), 192 (2009).Google Scholar
Kühnlein, F., Drummer, D., Rietzel, D., and Seefried, A.: Degradation behavior and material properties of PA12-plastic powders processed by powder based additive manufacturing technologies. In 3rd International Conference on Additive Technologies; DAAAM Specialized Conference (DAAAM International, Vienna, Austria, 2010).Google Scholar
Rietzel, D., Kühnlein, F., Hülder, G., and Drummer, D.: Untersuchung der Materialalterung bei pulverbasierten Schichtbauverfahren. RTejournal 7, (Juli 2010).Google Scholar
Zarringhalam, H.: Investigation into crystallinity and degree of particle melt in selective laser sintering. In Rapid Manufacturing Research Group (Loughborough University, Loughborough, UK, 2007), p. 237.Google Scholar
Mielicki, M.S.C., Wegner, A., Gronhoff, B., Wortberg, J., and Witt, G.: Prediction of PA12 melt viscosity in laser sintering by a time and temperature dependent rheological model. RTejournal. 32, (2012).Google Scholar
Plummer, K., Vasquez, M., Majewski, C., and Hopkinson, N.: Study into the recyclability of a thermoplastic polyurethane powder for use in laser sintering. J. Eng. Manuf. 226(7), 10 (2012).Google Scholar
Levy, G.N., Boehler, P., Martinoni, R., Schindel, R., and Schleiss, P.: Controlled local properties in the same part with sintaflex a new elastomer powder material for the SLS process. In 16th Solid Freeform Fabrication Symposium (University of Texas at Austin, 2005), p. 197.Google Scholar
Gibson, I. and Shi, D.: Material properties and fabrication parameters in selective laser sintering process. Rapid Prototyping J. 3(4), 129 (1997).Google Scholar
Savalani, M.M., Hao, L., Dickens, P.M., Zhang, Y., Tanner, K.E., and Harris, R.A.: The effects and interactions of fabrication parameters on the properties of selective laser sintered hydroxyapatite polyamide composite biomaterials. Rapid Prototyping J. 18(1), 13 (2012).Google Scholar
Drummer, D., Drexler, M., and Kühnlein, F.: Effects on the density distribution of SLS-parts. Phys. Procedia 39, (2012).Google Scholar
Dupin, S., Lame, O., Barrès, C., and Charmeau, J-Y.: Microstructural origin of physical and mechanical properties of polyamide 12 processed by laser sintering. Eur. Polym. J. 48, 11 (2012).Google Scholar
Soe, S.P., Martindale, N., Constantinou, C., and Robinson, M.: Mechanical characterisation of Duraform® Flex for FEA hyperelastic material modelling. Polym. Test. 34, 103 (2014).Google Scholar
3D Systems: DuraForm® Flex Plastic - Datasheet (3D Systems, Inc., 2014) Material data sheet and technical specifications.Google Scholar
Deutsches Institut für Normung e. V.: DIN 53504:2009-10. Testing of Rubber – Determination of Tensile Strength at Break, Tensile Stress at Yield, Elongation at Break and Stress Values in a Tensile Test (Beuth Verlag GmbH, Berlin, Germany, 2009), p. 18.Google Scholar
Solórzano, E., Pardo-Alonso, S., de Saja, J.A., and Rodriguez-Perez, M.A.: X-ray radioscopy in-situ studies in thermoplastic polymer foams. Colloids Surf., A 438, 167 (2013).Google Scholar
Van Geet, M., Swennen, R., and Wevers, M.: Quantitative analysis of reservoir rocks by microfocus x-ray computerised tomography. Sediment. Geol. 132, 25 (1999).CrossRefGoogle Scholar
Solórzano, E., Pinto, J., Pardo, S., Garcia-Moreno, F., and Rodriguez-Perez, M.A.: Application of a microfocus x-ray imaging apparatus to the study of cellular polymers. Polym. Test. 32, 321 (2012).Google Scholar
Phoenix|x-ray Systems + Services GmbH: Operator Training. phoenix|x-ray Systems + Services GmbH, Wunstorf, Germany, Volume: 2.5.Google Scholar
Ehrenstein, G.W. and Pongratz, S.: Beständigkeit von Kunststoffen (Carl Hanser Verlag, München, Germany, 2007).Google Scholar
Kühnlein, F., Drummer, D., Wudy, K., and Drexler, M.: Alterungsmechanismen der Kunststoffpulvern bei der Verarbeitung und deren Einfluss auf prozessrelevante Materialeigenschaften. In Industriekolloquium des Sonderforschungsbereichs 814-Additive Fertigung, Sonderforschungsbereichs 814-Additive Fertigung, Prof. Dr.-Ing. Dietmar Drummer and Universität Erlangen-Nürnberg, 2012), p. 49.Google Scholar
Wilkie, C.A.: TGA/FTIR: An extremely useful technique for studying polymer degradation. Polym. Degrad. Stab. 66, 301 (1998).Google Scholar
Zhang, Y., Maxted, J., Barber, A., Lowe, C., and Smith, R.: The durability of clear polyurethane coil coatings studied by FTIR peak fitting. Polym. Degrad. Stab. 98 527 (2012).Google Scholar
Raatz, G.: Partikelformanalyse (Retsch Technology, Haan, Germany, 2012).Google Scholar
Retsch Technology GmbH: Operating Instructions/Manual Particle Size Analysis System CAMSIZER and CAMSIZER XT (Retsch Technology GmbH, Haan, Germany, 2012).Google Scholar
Freeman, R.: Measuring the flow properties of consolidated, conditioned and aerated powders—A comparative study using a powder rheometer and a rotational shear cell. Powder Technol. 174, 9 (2006).Google Scholar
Freeman Technology: Stability Method (W7011) FT-4 Methodology. (Freeman Technology, Tewkesbury, UK, 2008).Google Scholar
Ziegelmeier, S., Wöllecke, F., Tuck, C., Goodridge, R.D., and Hague, R.: Characterizing the bulk & flow behaviour of LS polymer powders. In Twenty Forth Annual International Solid Freeform Fabrication Symposium – An Additive Manufacturing Conference (University of Texas at Austin, Mechanical Engineering, Austin, TX, 2013).Google Scholar
Merkus, H.G.: Particle Size Measurements: Fundamentals, Practice, Quality (Springer, Heidelberg, Germany, 2009).Google Scholar
Bellehumeur, C.T., Kontopoulou, M., and Vlachopoulos, J.: The role of viscoelasticity in polymer sintering. Rheol. Acta 37(3), 270 (1998).Google Scholar
Ziegelmeier, S., Christou, P., Wöllecke, F., Tuck, C., Goodridge, R., Hague, R., Krampe, E., and Wintermantel, E.: An experimental study into the effects of bulk and flow behaviour of Laser Sintering polymer powders on resulting part properties, J. Mater. Process. Technol. (2014). DOI: http://dx.doi.org/10.1016/j.jmatprotec.2014.07.029.Google Scholar
Beal, V.E., Paggi, R.A., Salmoria, G.V., and Lago, A.: Statistical evaluation of laser energy density effect on mechanical properties of polyamide parts manufactured by selective laser sintering. J. Appl. Polym. Sci. 113(5), 2910 (2009).Google Scholar
Greco, A. and Maffezzoli, A.: Polymer melting and polymer powder sintering by thermal analysis. J. Therm. Anal. Calorim. 72(3), 1167 (2003).Google Scholar
Hopkinson, N., Majewski, C.E., and Zarringhalam, H.: Quantifying the degree of particle melt in selective laser sintering®. CIRP Ann.-Manuf. Technol. 58(1), 197 (2009).Google Scholar
Kontopoulou, M. and Vlachopoulos, J.: Melting and densification of thermoplastic powders. Polym. Eng. Sci. 41(2), 15 (2011).Google Scholar
Hernández, E.: Effect of degradation during processing on the melt viscosity of a thermoplastic polyurethane. In Simposio de Metrología (National Centre of Metrology (CENAM), Queretaro, Mexico 2008), pp. 1.Google Scholar
Domininghaus, H., Elsner, P., Eyerer, P., and Hirth, T.: Kunststoffe - Eigenschaften und Anwendungen (Springer Verlag, Heidelberg, Germany 2008).Google Scholar
Lovett, D. and Eastop, D.: The degradation of polyester polyurethane: preliminary study of 1960s foam-laminated dresses. In Contributions to the Bilbao Congress [of IIC] (International Institute for Conservation of Historic and Artistic Works, London, UK, 2004), p. 100.Google Scholar
Shieh, Y-T., Chen, H-T., Liu, K-H., and Twu, Y-K.: Thermal degradation of MDI-based segmented polyurethanes. J. Polym. Sci., Polym. Chem. 37, 9 (1999).Google Scholar
Suhara, F., Kutty, S.K.N., and Nando, G.B.: Thermal degradation of short polyester fiber-polyurethane elastomer composite. Polym. Degrad. Stab. 61(1), 9 (1998).CrossRefGoogle Scholar
Grassie, N., Zulfiqar, M., and Guy, M.I.: Thermal degradation of a series of polyester polyurethanes. J. Polym. Sci. 18, 10 (1980).Google Scholar
Petrovic, Z.S., Zavargo, Z., Flynn, J.H., and Macknight, W.: Thermal degradation of segmented polyurethanes. J. Appl. Polym. Sci. 51, 9 (1994).Google Scholar
Hesse, M., Meier, H., and Zeeh, B.: Spektroskopische Methoden in der organischen Chemie (Georg Thieme Verlag, Stuttgart, Germany, 2013).Google Scholar
Forrest, M.J.: Chemical Characterisation of Polyurethanes, in Rapra Review Reports (iSmithers Rapra Publishing, Shropshire, UK, 1999).Google Scholar
Lattimer, R.P. and Williams, R.C.: Low-temperature pyrolysis products from a polyether-based urethane. J. Anal. Appl. Pyrolysis 63, 85 (2001).Google Scholar
Lattimer, R.P., Polce, M.J., and Wesdemiotis, C.: MALDI-MS analysis of pyrolysis products from a segmented polyurethane. J. Anal. Appl. Pyrolysis 48, 1 (1998).Google Scholar
Chapman, T.M., Rakiewicz-Nemeth, D.M., Swestock, J., and Benrashid, R.: Polyurethane elastomers with hydrolytic and thermooxidative stability. I. Polyurethanes with N-alkylated polyamide soft blocks. J. Polym. Sci. 28(6), 1473 (1990).Google Scholar
Sauer, A.: Optimierung der Bauteileigenschaften beim Selektiven Lasersintern von Thermoplasten (Universität Duisburg-Essen, Aachen, Germany, 2005).Google Scholar
Fu, X., Huck, D., Makein, L., Armstrong, B., Willen, U., and Freeman, T.: Effect of particle shape and size on flow properties of lactose powders. Particuology 10, 6 (2011).Google Scholar
Kaddar, W.: Die generative Fertigung mittels Laser-Sintern: Scanstrategien, Einflüsse verschiedener Prozessparameter auf die mechanischen und optischen Eigenschaften beim LS von Thermoplasten und deren Nachbearbeitungsmöglichkeiten (Universität Duisburg-Essen, Essen, Germany, 2010).Google Scholar