3D Printing of a Self-Healing Thermoplastic Polyurethane through FDM: From Polymer Slab to Mechanical Assessment.

Linda Ritzen,Santiago J Garcia,Vincenzo Montano

doi:10.3390/polym13020305

Abstract

The use of self-healing (SH) polymers to make 3D-printed polymeric parts offers the potential to increase the quality of 3D-printed parts and to increase their durability and damage tolerance due to their (on-demand) dynamic nature. Nevertheless, 3D-printing of such dynamic polymers is not a straightforward process due to their polymer architecture and rheological complexity and the limited quantities produced at lab-scale. This limits the exploration of the full potential of self-healing polymers. In this paper, we present the complete process for fused deposition modelling of a room temperature self-healing polyurethane. Starting from the synthesis and polymer slab manufacturing, we processed the polymer into a continuous filament and 3D printed parts. For the characterization of the 3D printed parts, we used a compression cut test, which proved useful when limited amount of material is available. The test was able to quasi-quantitatively assess both bulk and 3D printed samples and their self-healing behavior. The mechanical and healing behavior of the 3D printed self-healing polyurethane was highly similar to that of the bulk SH polymer. This indicates that the self-healing property of the polymer was retained even after multiple processing steps and printing. Compared to a commercial 3D-printing thermoplastic polyurethane, the self-healing polymer displayed a smaller mechanical dependency on the printing conditions with the added value of healing cuts at room temperature.

Highlights

Additive manufacturing (AM), or three-dimensional (3D) printing, of smart polymers is a rapidly growing field [1,2,3]
We report a protocol to 3D-print and mechanically test a previously reported [25]) low-temperature self-healing thermoplastic polyurethane (SH-Thermoplastic polyurethanes (TPU)) using fused deposition modelling
−1 is associated with the stretching vibration of hydrogen bonded N-H groups, or cm xz-direction, the sample was positioned such that the blade moved along the z direction

Summary

Introduction

Additive manufacturing (AM), or three-dimensional (3D) printing, of smart polymers is a rapidly growing field [1,2,3]. The different AM techniques offer in principle the possibility to manufacture, often expensive, smart materials in a versatile, minimum-waste manner. Through careful design of the polymer architecture, reversible or dynamic bonds can be implemented in the polymer network in a search for a balance between healing and sufficiently good mechanical properties [4]. These dynamic bonds can be intermolecular reversible covalent bonds, such as Diels–Alder cycloaddition and polysulphide reactions, or supramolecular, such as hydrogen bonding or ionic clustering. The recovery of mechanical and other functional properties such as barrier or electrical conductivity of self-healing polymers is the subject of significant attention, the translation of such concepts to 3D printed parts has received very limited attention, mostly focused on the printability of a couple of polymers with limited attention to the study of the mechanical properties or healing potential of the printed parts [3]

Methods

Results

Conclusion