Processing-structure-property relationships for polymer nanodielectrics

Prasad, Aditya Shanker
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Schadler, L. S. (Linda S.)
Plawsky, Joel L., 1957-
Ozisik, Rahmi
Palermo, Edmund
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Materials engineering
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This thesis reports work done to understand the effect of different extrusion processing parameters on the dispersion state of the nanocomposites and additionally, the effect of the dispersion state on the dielectric permittivity and breakdown strength of the nanocomposites. SiO¬2 nanoparticles were surface modified with different monofunctional silanes to change their wetting characteristics with respect to PMMMA and PS matrices. Compatibility between the modified nanoparticle and polymer matrix was determined by the ratio of work of adhesions of polymer-filler and filler-filler (WPF/WFF). Nanocomposites were prepared in a twin screw extruder and the microstructure was characterized using TEM imaging and image analysis tools. It was found that the final dispersion state was dependent on the WPF/WFF of the nanocomposite system. For WPF/WFF <1, the systems were heavily agglomerated and the final dispersion state indicated an erosion dominated mechanism of deagglomeration. For WPF/WFF ≥ 1, the systems exhibited good dispersion which was indicative of a rupture dominated mechanism. Further analysis showed that the infiltration of the polymer matrix into the nanoparticle agglomerate greatly reduced the cohesive strength between the nanoparticles and facilitated the transition of deagglomeration mechanisms.
May 2019
School of Engineering
Dept. of Materials Science and Engineering
Rensselaer Polytechnic Institute, Troy, NY
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