(488f) Fabrication of Polymer-Graphite Nanocomposites Via Cryogenic Milling

Polymer nanocomposites are a class of advanced materials that contain small amounts of nanoscale fillers dispersed within a polymer matrix. These ?nano?fillers can greatly enhance the physical properties of the resulting composites, such as mechanical stiffness and toughness, thermal stability, electrical conductivity, chemical resistance, and reduced gas permeability. Common nanofillers include montmorillonite (clay) and carbon nanotubes, but graphite has recently become a popular nanofiller of choice because graphite nanoplatelets are structurally similar to clay and are chemically comparable to carbon nanotubes.

There are several widely-used techniques used to produce polymer-graphite nanocomposites, such as solution mixing, in situ polymerization, and melt mixing; each has notable advantages and disadvantages. Solid-state processing is an alternative method of fabricating polymer-based nanocomposites. This type of processing method utilizes high amounts of shear and/or compressive forces carried out below the melt and/or glass transition temperature of the polymer and the filler. A prototypical example of such a process is solid-state shear pulverization (SSSP) [1-3]. Another simple solid-state method is cryogenic milling, in which a blend of polymer and nanofiller is repeatedly struck with a metal impactor within a cylindrical container at cryogenic temperature.

In the present paper, several polymer-graphite nanocomposites were fabricated using batch-scale cryogenic compounding. Solid-state processed nanocomposites were compared with equivalent samples made via conventional batch-scale melt-mixing. Structural characterization was conducted by X-ray diffraction and electron microscopy. Various mechanical, thermal, electrical and gas barrier properties were also conducted.

[1] Kasimatis, K. G.; Torkelson, J. M. PMSE Preprints (American Chemical Society, Division of Polymeric Materials: Science and Engineering) 91, 173-174 (2004).

[2] Wakabayashi, K.; Pierre, C.; Dikin, D. A.; Ruoff, R. S.; Ramanathan, T.; Brinson, L. C.; Torkelson, J. M. Macromolecules 41(6), 1905-1908 (2008).

[3] Masuda, J; Torkelson, J. M. Macromolecules 41(16), 5974-5977 (2008).