Tensile properties of the FFF-processed thermoplastic polyurethane (TPU) elastomer

Budi Arifvianto,Rini Dharmastiti,Benidiktus Tulung Prayoga,Suyitno Suyitno,Teguh Nur Iman,Urip Agus Salim,Muslim Mahardika

doi:10.1007/s00170-021-07712-0

Abstract

Fused filament fabrication (FFF) has become one of the most popular, practical, and low-cost additive manufacturing techniques for fabricating geometrically complex thermoplastic polyurethane (TPU) elastomer. However, there are still some uncertainties concerning the relationship between several operating parameters applied in this technique and the mechanical properties of the processed material. In this research, the influences of extruder temperature and raster orientation on the mechanical properties of the FFF-processed TPU elastomer were studied. A series of uniaxial tensile tests was carried out to determine tensile strength, strain, and elastic modulus of TPU elastomer that had been printed with various extruder temperatures, i.e., 190–230 °C, and raster angles, i.e., 0–90°. Thermal and chemical characterizations were also conducted to support the analysis in this research. The results showed the ductile and elastic characteristics of the FFF-processed TPU, with specific tensile strength and strain that could reach up to 39 MPa and 600%, respectively. The failure mechanisms operating on the FFF-processed TPU and the result of stress analysis by using the developed Mohr’s circle are also discussed in this paper. In conclusion, the extrusion temperature of 200 °C and raster angle of 0° could be preferred to be applied in the FFF process to achieve high strength and ductile TPU elastomer.

Highlights

Fused filament fabrication (FFF), or interchangeably called fused deposition modelling (FDM) after being patented by Scott Crump in 1989 [1], has become one of the most popular, practical, and yet inexpensive additive manufacturing techniques for the fabrication of a geometrically-complex and custom-designed polymer-based part [2, 3]
A series of tensile tests was performed in this research by using a dog-bone shaped specimen that had been printed from a yellow thermoplastic polyurethane (TPU) filament according to ASTM D638-14 standard
A series of characterizations by using differential scanning calorimetry (DSC) and Fourier transform infra-red (FTIR) was conducted to examine the phase changes that possibly occurred once the TPU filament was heated and cooled down during the printing process with the temperature ranges used in this research

Summary

Introduction

Fused filament fabrication (FFF), or interchangeably called fused deposition modelling (FDM) after being patented by Scott Crump in 1989 [1], has become one of the most popular, practical, and yet inexpensive additive manufacturing techniques for the fabrication of a geometrically-complex and custom-designed polymer-based part [2, 3]. The principle of the FFF relies on the extrusion and deposition of a melted polymeric filament to form a stack of slices that builds up the designed 3dimensional part [4] The applications of this technique have so far been growing, starting as a tool for rapid prototyping process up to the fabrication of various consumer goods and patient-specific biomedical implants [5,6,7]. The FFF has been used to fabricate drug-loaded TPU forms, which enabled personalized dosage for patient treatment [9] Considering such potential applications, the performances of the additively-manufactured TPU elastomer should be ensured, including those which are related to its load-bearing capabilities [1]

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Discussion

Conclusion