Sabah Javaid

Date of Award

8-5-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biomedical Engineering

First Advisor

Surojit Gupta

Second Advisor

Naima Kaabouch

Abstract

We report the synthesis and characterization of PEEK-MAX (Ti3SiC2, Ti3AlC2,and Cr2AlC), and PEEK-MoAlB, (DDGS500 – pyrolyzed Distiller’s dried grains with soluble (DDGS)), metal (Mo) and PEEK-ceramic (Xonotlite) based PEEK composites, by hot-pressing. A systematic study was done to understand the effect of these additives on functional and mechanical properties. Initially, these composites were synthesized by hot pressing. Detailed microstructure analysis by scanning electron microscopy showed that at higher concentration (≥10 vol%), the Ti3SiC2, Ti3AlC2 and PEEK-MoAlB particles segregated at the phase boundaries and formed interpenetrating micro-networks. PEEK-Cr2AlC were well dispersed in the PEEK matrix. Microstructure study of the composites showed that DDGS500 powder particulates were well dispersed within the PEEK matrix after the addition of 5 vol%. However, at higher concentration of 10 and 20 vol%, the particles segregated at the phase boundaries. Mo and Xonotlite particles were segregated at the phase boundaries even at 5 vol% concentration. The addition of MAX phases or MoAlB reduced the crystallization temperature and melting point of these composites. PEEK reinforced with 10 vol% Ti3SiC2, Ti3AlC2 and MoAlB showed plastic failure, and higher strength than PEEK. Comparatively, PEEK reinforced with 10 vol% Cr2AlC did not show any enhancement. All the PEEK-MAX and PEEK-MoAlB composites showed triboactive behavior and enhanced wear resistance. The addition of DDGS500, PEEK-Mo and PEEK-Xonotlite particulates lowered the wear rate until 10 vol% by several orders of magnitude and stabilized the friction coefficient (μ) versus distance profile. PEEK-20 vol% Xonotlite which showed hydrophilic behavior with a decrease in contact angle as a function of time which shows that Xonotlite can be a promising additive for increasing hydrophilicity of PEEK based composites for biomedical applications. PEEK composites fluid lubrication tribology behavior was also studied in the presence of distilled deionized water and simulated body fluid (SBF). PEEK composites showed improvement in the tribological behavior. In addition, PEEK composites immersed in SBF, also shown formation of bone growth.

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