(602c) Residence Time Distribution in a Chilled Polymer Extruder: Solid-State Shear Pulverization (SSSP)

Solid-state shear
pulverization (SSSP) is a twin screw extruder-based
polymer processing methodology that has been developed and applied to a wide
range of systems, such as homopolymer modification [1], polymer blend [2] and
composites/ nanocomposite [3] synthesis, and plastics recycling [4]. In SSSP,
material is kept below its melt and glass transition temperatures and in the
solid-state, which leads to an exposure to high shear and compressive forces by
the screw elements.

Akin to conventional
twin screw extruders, SSSP has an extensive operating
space, governed by numerous processing parameters like screw configuration,
rotation speed, throughput, barrel temperature, and feed particle size.
Detailed processing-structure-processing relationships in SSSP can be realized
when the complex interplay between the numerous operating parameters can be
consolidated if their interactive responses can be translated to universal
processing outputs.

One such output,
residence time distribution (RTD) [5], is the focus of this paper. Based on
well-established RTD studies in the conventional TSE arena [6], tracer pulse
experiments are conducted for a range of SSSP operating conditions, and
important characteristics and trends are extracted towards a better
understanding of the SSSP process, with the vision of eventually
relating them to the structure and property modifications observed in the
SSSP-processed materials.  

[1] M.F. Diop and J.M. Torkelson,
Polymer, 60, 77 (2015).

[2] A.H. Lebovitz, K. Khait and J.M. Torkelson, Polymer, 44, 199 (2003).

[3] K. Wakabayashi, C. Pierre, D.A.
Dikin, R.S. Ruoff, T. Ramanathan, L.C. Brinson and
J.M. Torkelson,  Macromolecules, 41,
1905 (2008).

[4] K. Khait, S.H. Carr,
and M.H. Mack, Solid-State Shear Pulverization, Boca Raton, CRC Press (2001).

[5] O. Levenspiel, Chemical Reaction Engineering,
New York, Wiley (1999).

[6] J. Gao, G.C. Walsh, D. Bigio, R.M.
Briber, and M.D. Wetzel, Polymer Engineering and Science, 40,
227 (2000).