FFF 3D Printing: Degradable Polymer Nanocomposities for Medical Applications

December 19, 2019 by Bridget O'Neal 3D Printing 3D Printing Materials

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In the recently published ‘Degradable Polymer Nanocomposites for Fused Filament Fabrication Applications,’ researchers from Ireland are exploring the massive use of plastics around the world, along with environmental concerns. In the medical field specifically, they highlight resorbable and degradable polymers, used in devices like implants, stents, drug delivery services, and more.

Fused Filament Fabrication (FFF) 3D printing has emerged as a popular technology for researchers engaged in the fabrication and study of items like medications in solid dosage forms. In this study, the authors explored how to create a degradable nanocomposite with polymers poly(ethylene oxide) (PEO) and poly(ε-caprolactone) (PCL) and the nanoclay halloysite nanotubes (HNTs) by utilization of hot-melt extrusion (HME). They also explored whether there is serious potential for such materials in relevant applications.

Once the materials were prepared via HME, they were tested regarding:

Melt flow indexing
Mechanical testing
Differential scanning calorimetry
Scanning electron microscopy

“From the characterization the most favorable blend was selected and HNTs of 2 and 6 weight percent were added with the same testing techniques employed to evaluate their influence on the material,” stated the researchers.

The team also endeavored to create a new filament for 3D printing, tested in a MakerBot Replicator 2X 3D printer to create a stent. As they began evaluating the study overall, the researchers noted that when they added the PCL to the PEO, a ‘plasticizing effect’ occurred. This was noticeable in both the melt flow index and when the blends reached their melting point; at that time, there an increase in the PCL.

The resultant extruded filament was utilized as the feedstock in a MakerBot Replicator 2X 3D printer in order to print a stent demonstrating the possibilities it offers for personalized medical uses.

Melt flow index results of Blend 4 and the two nanocomposite batches, Blend 4A and Blend 4B (n=3).

“The addition of the HNTs significantly increased the Young’s modulus 11 % and 25 % when the loading was 2 wt.% and 6 wt.% respectively,” explained the researchers.

Selected mechanical data for the batches under investigation where, E represents the Young’s modulus, σy is the yield stress and σmax is the maximum tensile stress (n=5).

Scanning electron microscopy (SEM) images of Blend 4 and the two nanocomposite batches, Blend 4A and Blend 4B

When performing microscopy, the researchers also saw no signs of outright HNT aggregation at the surface. They were also optimistic for high mixing efficiency via the HME.

“A small almond shaped accumulation of HNTs was observed on the surface of Blend 4A as shown with this accumulation was identified as HNTs using energydispersive x-ray spectroscopy.

“The work described the successful development of a filament feedstock from known degradable materials for use in Fused Filament Fabrication with the produced filament utilized in the fabrication of a stent. The use of this technology is promising as it may allow for the fabrication of stents tailored to a patient’s specific needs. Furthermore, there is also the potential application for loading drug molecules in the large lumen space of the HNTs which could slowly release as the device slowly degrades within the body,” concluded the researchers.

Work with composites has expanded greatly in recent years, from antioxidant PLA to wood composites to glass fiber—along with a host of different innovation within the medical realm involving devices like implants and stents.

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[Source / Images: ‘Degradable Polymer Nanocomposites for Fused Filament Fabrication Applications’]