Prioritization in investigating the potential of carbon based conductive filler, on carbon black (CB) and graphene nanoplatelet (GNP), to modify the mechanical, electrical and thermal properties of the polymer matrix was achieved via uniform dispersion and identifying the set of mechanical failure mechanism, which leads to relevant modification methods. The principle idea of this research study was to understand the function of immiscible polymer blend system towards the reduction of percolation threshold on conductive filler, via selective localization mechanism. This study thematically divided into five parts. In the first part, the electrical properties of CB in single matrix epoxy system was investigated and the percolation threshold was determined at 15 vol.% loading. In the second part, the dual matrixes system, which consists of epoxy and poly (methyl methacrylate) (PMMA) prepared via two different processing methods: solvent
dissolution (SD) and direct mixing (DM) were investigated. This part involved different processing methods in preparing the polymer blend system, which has led to selective localization of filler in the blend system. A variety of experimental methods was described which were employed to investigate the structure and properties of the composites. Using the predetermined CB percolation in single matrix system, the optimum PMMA content for both SD and DM methods are 40 and 10 vol.%, respectively. After that, the percolation threshold of CB for both dual matrixes system were investigated and determined at 10 and 5 vol.% for both SD and DM methods. Both methods successfully reduced the optimum CB loading in single matrix system, with
composites prepared from DM method outperformed SD method, in terms of mechanical and electrical properties, where increment of almost 19% on flexural strength and three order of magnitude on electrical bulk conductivity was observed on DM method as compared to single matrix system. Next, the GNP percolated loading was determined in single matrix epoxy system, where 1 vol.% of GNP was used in dual matrixes epoxy/PMMA system using DM method. Similar findings were observed, where the electrical conductivity of GNP filled epoxy/PMMA system increased two order of magnitude, with 30 vol.% PMMA content and the optimum loading of GNP reduced from 1 to 0.4 vol.%. Nevertheless, extensive studies were done on the interaction between fillers, PMMA, and epoxy, through mechanical and thermal properties. The final part of the thesis deals with surface modification on both CB and GNP, which consist of three different modification methods: wet oxidation, impregnation, and heat treatment. The appreciable improvement was measured in the mechanical properties, which electron microscopy was carried out to investigate the microstructure and interfacial interaction between the filler and matrix. The present work demonstrated the significant ability of immiscible polymer blends system to reduce the percolation threshold of both carbon based conductive fillers while surface modification on both CB and GNP show better dispersion and interfacial interaction. This open a broad horizon for a variety of application, especially conductive adhesives.
