PhD Proposal by Narayan Shirolkar
THE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING
GEORGIA INSTITUTE OF TECHNOLOGY
Under the provisions of the regulations for the degree
DOCTOR OF PHILOSOPHY
on Thursday, April 11, 2019
in MRDC 4211
will be held the
DISSERTATION PROPOSAL DEFENSE
"Processing, Structure, and Properties of Continuous Carbon Materials
with Different Cross-sectional Geometries: Towards Lighter Composites"
Prof. Satish Kumar, Advisor, MSE
Prof. Jonathan Colton, ME
Prof. Kyriaki Kalaitzidou, ME
Prof. Meisha Shofner, MSE
Prof. Natalie Stingelin, MSE
Carbon fibers are finding increased usage in a wide variety of applications ranging from aerospace to energy harvesting to sports goods etc. Lighter and stronger than aluminum as well as steel, carbon fibers are an attractive candidate for lightweight structural materials. Carbon fiber composites make up to 50% of the structural weight of modern fuel-efficient aircrafts like the Boeing 787 Dreamliner. However, over the past three decades the improvement in the mechanical properties of carbon fibers has been incremental. In fact, the commercially used aerospace grade carbon fibers today were first manufactured more than 30 years ago. It is therefore necessary to explore alternative routes to improve the specific tensile properties of carbon fibers. This can be done by either reducing the density of the fibers without compromising their mechanical properties or by making composites with higher than 60% reinforcements by volume.
Using a gel-spun bi-component islands-in-a-sea precursor with polyacrylonitrile (PAN) as the sea component and polymethylmethacrylate (PMMA) as the sacrificial island component, hollow carbon fibers with a honeycomb cross-section have been produced. While these fibers have a tensile modulus higher than the commercially available carbon fibers, the tensile strength needs to be improved. In this work, by understanding the structural evolution of the fibers during continuous stabilization and carbonization, attempts will be made to further improve the mechanical properties of the hollow carbon fibers.
The specific mechanical properties of the composites can be improved if higher carbon loading is achieved. To achieve this, an alternative geometry viz. near rectangular film cross-section is explored. It is hypothesized that carbon films as compared to fibers, will allow higher carbon loading in composites. Roll-to-roll manufacturing of continuous carbon films using continuous stabilization and carbonization is reported for the first time. Preliminary characterization results are reported. In this study, the processing of continuous gel-spun PAN based carbon films will be studied. Structure-property relationship will be investigated to optimize the carbon film manufacturing process.
Keywords: Hollow carbon fibers, carbon films, structural materials, lightweight materials