Date of Award

5-2023

Degree Type

Thesis

Degree Name

Master of Science in Mechanical Engineering

Department

Mechanical Engineering

First Advisor

Sikder, Prahaba

Second Advisor

Sinaki, Maryam Younessi

Third Advisor

Ning, Liqun

Subject Headings

PEEK, AMP, SEM, 3D printing, extrusion, medical implants, bio-active, parameters.

Abstract

Polyether ether ketone (PEEK) is a high-performance polymer material for developing implants for orthopedic, spinal, cranial, maxillofacial, and dentistry applications. However, the major limitation of PEEK implants is their bio-inertness, i.e., their incapability to integrate with tissues. Therefore, prior efforts have always focused on developing Hydroxyapatite (HA) coatings on PEEK or PEEK-HA composites or sulfonation of PEEK surface or plasma treatment. As opposed, in this study, we engineered a highly novel bio-ceramic known as amorphous magnesium phosphate (AMP), which surpasses the bioactivity and biodegradation kinetics of HA. In this study, we employed High energy planetary ball milling, a mechanical alloying technique, to incorporate Amorphous magnesium Phosphate (AMP) into PEEK matrix resulting in a novel polymer bio-ceramic composite. We systematically varied ball milling parameters to observe their effects on composite powders and thoroughly analyzed the composite mixture using Scanning Electron Microscope (SEM). Subsequently, we developed a uniform-diameter filament of PEEK-AMP bioactive composite via a single screw extrusion process, such that it can be used in a Fused Filament Fabrication (FFF)-3D Printing setup to develop design-specific multifunctional implants. Our results indicate that controlling extrusion parameters such as temperature gradient, screw speed, tension, and cooling rate are essential to extruding uniform-diameter filaments suitable for 3D Printing. Furthermore, rheological properties confirmed the suitability of the PEEK-AMP filaments for 3D Printing, and SEM revealed the uniform dispersion of the AMP particles in the PEEK matrix. Importantly, 3D printed PEEK-AMP composite samples exhibited a yield Strength of 89 MPa and Young's Modulus of 3.5 GPa, confirming that AMP incorporation in PEEK does not deteriorate the inherent properties of PEEK. Apparently, mechanical properties are controlled by varying the 3D printing parameters like bed plate temperature, chamber temperature, Nozzle temperature and printing speed followed by heat treatment process.

Moreover, we prove that 3D Printing can manufacture mechanically robust PEEK-AMP structures comparable to machined ones. This comprehensive study introduces a unique and first-of-its-kind bio-composite, better than existing ones, that can be used to develop standalone bioactive multi-functional implants for reconstructive and regenerative medicine and enhance patient and surgical outcomes.

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