Committee Members:

Prof. Karl Jacob, Advisor, MSE

Prof. Hamid Garmestani, Co-advisor, MSE

Prof. Chaitanya Deo, NRE/ME/MSE

Prof. Antonia Antoniou, ME

Oomman Thomas, Ph.D., MSE/Coim USA

Influence of Texture on Wear Behavior of 3D Printed HDPE/UHMWPE Bioimplant Material

Abstract:

Polyethylene is extensively used for implants in total joint arthroplasty. However, long-term clinical use suggests that surface wear of PE causes eventual implant failure. Hence tailoring the material response by altering microstructure via texturing to have minimal wear is beneficial to improve PE components durability and hence the implants longevity. In this study, the effect of texture and microstructure on wear behavior of two types of 3D printed HDPE/UHMWPE/HDPE_wax trimodal reactor blends with varying overall molecular weight Mwalong with 3D printed HDPE has been investigated and compared to that of injection molded samples. Texture has been induced in the polymer samples using injection molding or fused deposition modeling where 3D printing speed and orientation have been varied. The texture components have been characterized through pole figures and orientation distribution functions using Wide Angle X-ray Diffraction. To determine the effect of texture on the wear behavior of the polymer samples, the wear properties at different loads, frequencies, fret orientations and number of fret cycles have been characterized using NanoTests fretting module. The morphological features have been investigated using SEM and TEM. The thermal and mechanical properties have been characterized using DSC, DMA andmicroindentation. The trimodal blends showed presence of extended-chain UHMWPE and the wear resistance of the blends has been found to be greater than that of HDPE in almost all cases. Presence of UHMWPE increased the hardness and elastic modulus measured from indentation comparedto HDPE and increase in Mwof trimodal blend further increased these properties. The bulk density, a physical property, has been measured using a density meter to look at its correlation with mechanical properties but not much correlation was found. Overall, this work helps determine the global effect of texture on wear behavior and other physical, thermal, mechanical properties of the 3D printed HDPE/UHMWPE/HDPE_wax trimodal reactor blends useful to improve the longevity of implants.