Printability and Tensile Performance of 3D Printed Polyethylene Terephthalate Glycol Using Fused Deposition Modelling.

Sofiane Guessasma,Hedi Nouri,Sofiane Belhabib

doi:10.3390/polym11071220

Abstract

Polyethylene terephthalate glycol (PETG) is a thermoplastic formed by polyethylene terephthalate (PET) and ethylene glycol and known for his high impact resistance and ductility. The printability of PETG for fused deposition modelling (FDM) is studied by monitoring the filament temperature using an infra-red camera. The microstructural arrangement of 3D printed PETG is analysed by means of X-ray micro-tomography and tensile performance is investigated in a wide range of printing temperatures from 210 °C to 255 °C. A finite element model is implemented based on 3D microstructure of the printed material to reveal the deformation mechanisms and the role of the microstructural defects on the mechanical performance. The results show that PETG can be printed within a limited range of printing temperatures. The results suggest a significant loss of the mechanical performance due to the FDM processing and particularly a substantial reduction of the elongation at break is observed. The loss of this property is explained by the inhomogeneous deformation of the PETG filament. X-ray micro-tomography results reveal a limited amount of process-induced porosity, which only extends through the sample thickness. The FE predictions point out the combination of local shearing and inhomogeneous stretching that are correlated to the filament arrangement within the plane of construction.

Highlights

In fused deposition modelling (FDM), one of the versatile processes of additive manufacturing [1,2], the laying down of the polymeric material [3] occurs in a layer-by-layer basis according to complex toolpath trajectory [4].The unidirectional laying down process results in two types of discontinuities; one is related to the raster within the plane of construction, and the other through the building direction
The Differential scanning calorimetry (DSC) spectra corresponding to the heating and cooling stages of the as-received polyethylene terephthalate glycol (PETG)
Highlights a temperature range between 42 ◦ C and 111 ◦ C corresponding to the glass transition highlights a temperature range between 42 °C and 111 °C corresponding to the glass transition (Figure 1a)

Summary

Introduction

The unidirectional laying down process results in two types of discontinuities; one is related to the raster within the plane of construction, and the other through the building direction The combination of both discontinuities leads to a lack of structure cohesion within the 3D print and the genesis of 3D defects [5], which are essentially represented by a porosity network [6]. The effect of these defects can be significant on the mechanical performance that costs up one third of the performance of the feedstock material [6] Several studies tackled this problem by adjusting key process parameters of FDM such as the part orientation, layer thickness [7], printing speed, and printing temperature [8,9,10,11]. This last parameter is known to enhance the cohesive structure of the 3D printed material by lowering the Polymers 2019, 11, 1220; doi:10.3390/polym11071220 www.mdpi.com/journal/polymers

Objectives

Methods

Results

Conclusion