Understanding and Improving Mechanical Properties in 3D printed Parts Using a Dual‐Cure Acrylate‐Based Resin for Stereolithography

Abstract

Application of 3D printed structures via stereolithography (SLA) is limited by imprecise dimensional control and inferior mechanical properties. These challenges is attributed to poor understanding ofpolymerization behavior during the printing process and inadequate post-processing methods. The former via a modified version of Jacob’s working curve equation that incorporates the resin’s sub-linear response to irradiation intensity is addressed by the authors. This new model provides a more accurate approach to select 3D printing parameters given a desired z-resolution and conversion profile along the depth of the printed part. The authors use this improved model to motivate a novel material design that can be post-processed to be indistinguishable from the polymer at 100% conversion. This approach employs a dual initiating system in which photo-initiated printing is followed by a thermal post-cure to achieve uniform conversion. The authors show that this approach enables fast printing times (10 s per layer), exceptional horizontal resolution (1–10 microns), precise control over vertical resolution, and decreased surface corrugations on a 10’s of microns scale. The techniques described herein use an acrylate-based SLA resin, but the approach can be extended to other monomer systems to simultaneously achieve predictable properties and dimensions that are critical for application of additive manufacturing in load-bearing applications.

Stereolithographic 3D Printing for Deterministic Control over Integration in Dual‐Material Composites

“…Accounting for the three distinct events of oxygen inhibition, light‐induced polymerization, and dark polymerization, the scaling factor α for this resin was previously determined to be 0.68 (0.01) . With this scaling factor, conversion as a function of effective dose ( × time) reduces to a single master curve (Figure b).…”

“…Layer‐by‐layer printing was used to form a structure similar to Figure a, where two lattices of 125 µm thickness each were separated by cylindrical pillars of 200 µm diameter and 1.25 mm height ( Figure a). We employed our recent dual cure approach that uses a thermal post cure to achieve isotropic properties across each layer of the 3D printed parts . Two cases are shown to demonstrate control over integration in 3D.…”

Investigation on the structural, mechanical and in vitro biocompatibility features of CaZr4(PO4)6 influenced by Zn2+ substitutions

“…The advent of cracks during elevated heat treatment and the atomic arrangement of CaZr 4 (PO 4 ) 6 is reflected in the mechanical properties of the resultant material. A wide range of casting techniques and other modern fabrication tools are available to design the complicated ceramic materials into a well‐ordered microstructure that display commendable mechanical features (Lederle, Meyer, Brunotte, Kaldun, & Hübner, ; Uzcategui, Muralidharan, Ferguson, Bryant, & McLeod, ). The relatively moderate mechanical features displayed by the investigated CaZr 4 (PO 4 ) 6 compositions could be tailored using the alternative fabrication techniques to yield desired mechanical features mainly by considering the advantage of excellent structural stability displayed by CaZr 4 (PO 4 ) 6 at elevated temperatures.…”

Mechanical and Thermal Properties of 3D-Printed Thermosets by Stereolithography

“…The mechanical and thermal properties of the SLA 3Dprinted polymers are greatly influenced not only by the monomer materials and formulation, but also by the SLA 3D printing parameters, such as printing orientation [16,17] and layer thickness [18,19]. Since the photo resins are not fully crosslinked after the 3D printing, the post UV-cure can be used to further change the mechanical properties of specimens [20][21][22]. To take the advantages of unique capability of 3D printing to produce polymer samples with complex geometry and shape, recent studies include the 3D printing of complex architected interpenetrating material structures having triply periodic minimal surfaces, such as diamond, gyroid and Fecher Koch, for the study of structure-property-relationships in polymer materials [23].…”