Date of Award

5-1-2012

Degree Type

Thesis

University or Center

Clark Atlanta University(CAU)

School

School of Arts and Sciences

Degree Name

M.S.

Department

Chemistry

First Advisor

Dr. Eric A. Mintz

Second Advisor

Dr. Issifu Harruna

Third Advisor

Dr. Conrad Ingram

Abstract

It has previous been shown that multiwall carbon nanotubes (MWCNT5) and carbon nanofibers can be effectively dispersed in phenylethynyl terminated imide (PETI) resins by high torque melt mixing, and processed into polymer matrix composites with improved electrical, thermal and mechanical properties and improved resistance to moisture adsorption. PETI resins are candidates in a vast array of potential applications that include aerospace vehicles. We found that high torque melt mixing with the combination of energy transferred during melt mixing, and formation of charge transfer complexes between graphene and the PETI resin successfully delaminated graphite, which is considerably less expensive than MWCNTs or graphene, to give dispersed short stacks and possibly individual graphene sheets. Melt rheology was utilized to examine the dispersion of graphene in the PETI resin and the resulting modification of viscoelastic properties including complex viscosity, r, storage modulus, G’, and loss modulus, G’. Raman spectroscopy with 785 nm excitation, X-ray powder diffraction, and scanning electron microscope (SEM) were also used to verify the delamination of graphite to graphene and short graphene stacks. The examination PETI 298 rheological behavior, mirroring resin transfer molding processing conditions, established that PETI 298 can be readily shear thinned, behaving as a non-Newtonian fluid. PETI 298 and dispersed graphite/graphene composites also exhibited non-Newtonian behavior under these conditions, which indicated that these new materials could be processable by Resin Transfer Molding (RTM). Differential scanning calorimetry (DSC) studies on the melt mixed PETI 298 graphite composites indicate that these nanocomposites can be fully cured at 371 °C, to five full cured loaded polyimides with high glass transition temperatures (Tg).


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