Selective Laser Sintering of High-Temperature Thermoset Polymer

Md Sahid Hassan,Kazi Md Masum Billah,Evgeny Shafirovich,Sergio Sepulveda,Yirong Lin,Jasmine Whitaker,James Keating,Sergio Cordova,Jaime Eduardo Regis,Thomas Robison,Cory Marquez,Samuel Ernesto Hall

doi:10.3390/jcs6020041

Abstract

Thermoplastic materials such as PA12 and PA6 have been extensively employed in Selective Laser Sintering (SLS) 3D printing applications due to their printability, processability, and crystalline structure. However, thermoplastic-based materials lack polymer inter-chain bonding, resulting in inferior mechanical and thermal properties and relatively low fatigue behavior. Therefore, 3D printing of high-performance crosslinked thermosets using SLS technology is paramount to pursue as an alternative to thermoplastics. In this work, a thermoset resin was successfully 3D printed using SLS, and its thermal stability of printed parts after a multi-step post-curing process was investigated. Dimensionally stable and high glass transition temperature (Tg: ~300 °C) thermoset parts were fabricated using SLS. The polymer crosslinking mechanism during the printing and curing process was investigated through FTIR spectra, while the mechanical stability of the SLS 3D-printed thermoset was characterized through compression tests. It is found that 100% crosslinked thermoset can be 3D printed with 900% higher compressive strength than printed green parts.

Highlights

IntroductionSelective Laser Sintering (SLS) is an additive manufacturing (AM) technique (i.e., 3D printing) that mainly deals with polymer materials in the powder form, which has the advantages of manufacturing complex objects and shapes without the need of support structures, compared to other AM techniques [1]
Printing) that mainly deals with polymer materials in the powder form, which has the advantages of manufacturing complex objects and shapes without the need of support structures, compared to other additive manufacturing (AM) techniques [1]
This paper shows the optimization of Selective Laser Sintering (SLS) printing parameters for BMI thermoset powder to obtain dimensionally accurate printed parts, along with its successful curing process

Summary

Introduction

Selective Laser Sintering (SLS) is an additive manufacturing (AM) technique (i.e., 3D printing) that mainly deals with polymer materials in the powder form, which has the advantages of manufacturing complex objects and shapes without the need of support structures, compared to other AM techniques [1]. 3D printing ceramics by SLS for sophisticated and well-defined structures such as gears and casting molds were fabricated using Aluminum Oxide (Al2 O3 )-based mixed powder. Such complex shapes were manufactured by adding different binders in the matrix that enhanced the material’s properties [6,7]. They carry the practicability to fabricate complex shapes as functional parts, such as the Bionic Handling assistant using PA-12, a common thermoplastic material that shows good processability for SLS [8]. The applications of SLS depend upon the requirements of the material properties for the desired application, such as fabrication of biomedical devices, which demands more remarkable accuracy and control over producing intricate geometric figures [9], or even the potential of printing materials that can withstand hot temperatures for aerospace applications

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