|Organization or Institution||Florida State University|
Rheology and Ceramic Yield of Preceramic Polymer Grafted Nanoparticle Composites
Florida State University
Ceramics derived from preceramic polymers are used in applications such as energy storage, catalysis, and coatings for aerospace. Preceramic polymers such as SMP-877 and SMP-10 are commonly used in a number of these applications due to their high ceramic yield, but have significant volume shrinkage when converted to ceramics, as well as crack and pore formation. They have a low enough viscosity to flow easily into cracks and pores, but they have poor processability. Fillers are introduced to make a more viscoelastic and processible material. However, issues arise when fillers are introduced such as aggregation and phase separation. We hypothesize that we can improve filler dispersibility and resultant mechanical properties by attaching the preceramic polymer poly(1,1-dimethylpropylsilane) to silica nanoparticles and converting them to ceramics. Dispersions of polymer grafted nanoparticles were characterized by rheology, thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The matrices were liquids while the HNP’s were viscoelastic solids and had moduli of 2000 Pa. The moduli (elastic moduli – G’) could be tuned by the relative amounts of HNP’s and the matrices but G’ was shown to be dependent on only the silica core of the HNP’s and was not dependent on the matrix. The yield strain of the HNP’s in SMP-877 and SMP-10 were close to 100% as compared to bare silica (10%) in the different matrices thus highlighting the effectiveness of the grafted polymers on yielding behavior. The ceramic yields of HNP’s in SMP-10 were found to be higher than that of HNP in SMP-877 and comparable to the yield of the matrices. Thus, this work resulted in the development of a novel viscoelastic ceramic ink with similar yields to commercially available matrices and better processability.