Volume‐exclusion effects in polyethylene blends filled with carbon black, graphite, or carbon fiber

Abstract

Conductive polymer composites possessing a low percolation‐threshold concentration as a result of double percolation of a conductive filler and its host phase in an immiscible polymer blend afford a desirable alternative to conventional composites. In this work, blends of high‐density polyethylene (HDPE) and ultrahigh molecular weight polyethylene (UHMWPE) were used to produce ternary composites containing either carbon black (CB), graphite (G), or carbon fiber (CF). Blend composition had a synergistic effect on electrical conductivity, with pronounced conductivity maxima observed at about 70–80 wt % UHMWPE in the CB and G composites. A much broader maximum occurred at about 25 wt % UHMWPE in composites prepared with CF. Optical and electron microscopies were used to ascertain the extent to which the polymers, and hence filler particles, are segregated. Differential scanning calorimetry of the composites confirmed that the constituent polymers are indistinguishable in terms of their thermal signatures and virtually unaffected by the presence of any of the fillers examined here. Dynamic mechanical analysis revealed that CF imparts the greatest stiffness and thermal stability to the composites. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1013–1023, 2002

Modeling and Testing of the Viscoelastic Properties of a Graphite Nanoplatelet/Epoxy Composite

“…For all three experimental sets of data, the storage modulus (or Young's modulus for the tensile tests) increases with an increasing nanoplatelet volume fraction, as expected. This trend is confirmed by results from studies on graphite platelet/Polyethylene composites (Thongruang, Balik and Spontak, 2002) and graphite nanoplatelet/epoxy composites (Fukushima and Drzal, 2002). The only exception to this observation is the 0.5% volume fraction specimen with 15 µm nanoplatelets, for which the storage modulus from nanoindentation is about equal to that of the epoxy material.…”

“…For example, graphite nanoplatelet/polymer composites have been a focus of recent development (Chen, Wu, Weng, 2001;Fukushima and Drzal, 2002;Pan, Yu, Ou, 2000;Thongruang, Balik and Spontak, 2002;Yalcin, Valladares and Cakmak, 2003;Zheng, Wu, Wang, 2004) for use as low-cost, lightweight materials with mechanical properties potentially superior to those of pure polymers without the penalty of increased weight. In order to facilitate the development of these new materials for aerospace applications, modeling and characterization procedures must be developed that address the unique characteristics of nanostructured materials and provide a multi-scale approach that spans the nano-to macro-length scales.…”

Electrical and thermal studies of the distribution of carbon black in a polyester matrix in the presence of aluminum oxide

“…This may be due to the uniform distribution of HAF particles in the presence of Al 2 O 3 , the volume effect, or both. 17,18 The presence of Al 2 O 3 may improve the filler distribution by lowering the aggregate size and consequently enhance the formation of the network; in addition, Al 2 O 3 is a conducting material. This finds further justification in SEM micrographs.…”

Mechanical and thermal properties of oil palm wood sawdust reinforced post-consumer polyethylene composites

“…4. In all formulations, the storage modulus gradually decreased with increasing temperature and then suddenly dropped as the material became sufficiently soft 15 . The storage modulus significantly increased with higher proportions of OWS to PCR-HDPE.…”