Effect of Printing Temperature on Mechanical and Viscoelastic Properties of Ultra-flexible Thermoplastic Polyurethane in Material Extrusion Additive Manufacturing

Effect of Printing Temperature on Mechanical and Viscoelastic Properties of Ultra-flexible Thermoplastic Polyurethane in Material Extrusion Additive Manufacturing

Material extrusion (ME) is one of the additive manufacturing methods and widely used to produce polymer-based parts. Thermoplastic polyurethane (TPU) is a relatively new material in ME. It has microdomains consisting of hard segments (HS) and soft segments (SS) in varying proportions. This structura...

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Bibliographic Details
Published in:Journal of materials engineering and performance Vol. 31; no. 5; pp. 3679 - 3687
Main Authors: Gumus, Omer Yunus, Ilhan, Recep, Canli, Berat Enes
Format: Journal Article
Language:English
Published: New York Springer US 01-05-2022
Subjects:
Characterization and Evaluation of Materials
Chemistry and Materials Science
Corrosion and Coatings
Engineering Design
Materials Science
Quality Control
Reliability
Safety and Risk
Technical Article
Tribology
hardness
additive manufacturing
printing temperature
TPU
material extrusion
mechanical properties
viscoelastic properties
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Summary:Material extrusion (ME) is one of the additive manufacturing methods and widely used to produce polymer-based parts. Thermoplastic polyurethane (TPU) is a relatively new material in ME. It has microdomains consisting of hard segments (HS) and soft segments (SS) in varying proportions. This structural complexity and weak interactions between HS and SS cause the properties of TPUs to become very sensitive to processing parameters such as temperature. In this study, the effect of printing temperature in a range of 170-250 °C on the physical, mechanical, and viscoelastic properties of ultra-flexible TPU (Shore A 60) samples was investigated. Furthermore, to elucidate the effect of the manufacturing method, a sample prepared by compression molding (CM) at 230 °C was used. Thermal transitions of the samples were analyzed by DSC. Increasing T g values were observed in correlation with increased printing temperature. A relation between T g and hardness values was thus established. In order to observe molecular weight ( M ) changes after printing, zero shear viscosities ( η 0 ) of polymer solutions were examined and preserved M values up to 200 °C were detected. Mechanical properties of the samples were analyzed through tensile tests. Among the samples including CM, the highest tensile strength and elongation at break were 37.6 MPa and 921%, respectively, which was detected for the sample printed at 230 °C. Oscillation tests revealed that both entanglements and HS content influence storages modulus ( G ′). Among the printed parts, highest G ′ value was measured at 220 °C printing temperature. This result was attributed to the synergistic effect of entanglement and HS. Furthermore, it is concluded that chain alignment has greater contribution on mechanical properties than M , whereas viscoelastic properties is more sensitive to M .
ISSN:1059-9495
1544-1024
DOI:10.1007/s11665-021-06510-9