Date of Award

2018

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering (PhD)

Administrative Home Department

Department of Chemical Engineering

Advisor 1

Julia King

Committee Member 1

Timothy Eisele

Committee Member 2

Ibrahim Miskioglu

Committee Member 3

Gregory Odegard

Abstract

Composites have many applications due to their high strength to weight ratio, chemical resistance, and the ability to tune properties like electrical resistivity (ER). In this work, polyetheretherketone (PEEK) and cycloaliphatic epoxy (CE) composites with different fillers were studied. PEEK composites contained up to 10 wt% Akzo Nobel Ketjenblack carbon black (CB), up to 15 wt% Asbury Carbons TC307 graphene nanoplatelets (GNP), up to 30 wt% Solvay carbon fiber (CF), and combinations of the three carbons. Formulations were developed for electrostatic dissipative and electrically conductive applications. The most conductive formulation was 7.5 wt% CB/30 wt% CF/PEEK, which had an electrical resistivity of 0.56 ohm-cm, a thermal conductivity twice that of the neat PEEK, a tensile strength of 145 MPa, and a tensile modulus of 18.4 GPa.

CE composites have high voltage and temperature applications such as aluminum conductor composite core (ACCC) power transmission lines because of their high ER, high glass transition temperature (Tg), stiffness, and aging resistance. Cabot CB and fumed silica were tested in CE. The results showed that up to 2 wt% carbon black or 4 wt% fumed silica had little effect on the electrical, thermal, or tensile properties of CE. Asbury TC307 GNP was added to CE and aged at elevated temperature and moisture levels. The results from flexure and dynamic mechanical testing indicate that the addition of up to 4 wt% GNP provides modest improvements in the stiffness and Tg for all aging levels, while the strength is improved for aging times below 400 hours. Imerys Nicron talc and Potters Spheriglass glass microspheres (glass MS) were tested in CE. Thermal conductivity increased from 0.15 W/m-K for neat CE to 0.25 W/m-K for both 20 wt% talc/CE and 40 wt% glass MS/CE. Tensile modulus increased for both fillers, and compared well with predicted values from micromechanical models. The talc/CE composites were aged at elevated temperature and moisture levels. Talc reduced water absorption and did not negatively affect aging effects on flexural strength and stiffness. Prior to these experiments, properties of these composites had not been previously reported in the open literature.

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