Filler Exfoliation and Dispersion in Polymer-As Received Graphite Nanocomposites via Cryogenic Milling

Publication Date

2011

Description

Nanocomposites from polypropylene and unmodified, as-received graphite were fabricated via solid-state cryogenic milling (cryomilling) process. Filler contents up to 10 wt% were studied with cryomilling cycles and postcryomill melt mixing option as processing parameters. Scanning electron microscopy and X-ray diffraction of the cryomilled samples reveal that graphite filler particles are partially exfoliated into nanoplatelets, as well as fragmented in the lateral dimensions, when incorporated into the polymer matrix. Various physical performance, including polymer crystallization rate, thermomechanical response, oxygen barrier, and electrical conductivity, is closely dictated by the filler morphology. An increase in cryomilling time leads to a higher degree of exfoliation, resulting in an enhancement in stiffness/strength, thermal stability, and electrical conductivity. Postcryomill melt mixing disperses the partially exfoliated graphite nanoplatelets, raising stiffness/strength and thermal stability while reducing electrical conductivity and oxygen permeability. The percolation threshold occurs between 1 and 3 wt%, with an optimum content for most properties at ∼3 wt%

Journal

Polymer Engineering and Science

Volume

51

Issue

11

First Page

2273

Last Page

2281

Department

Chemical Engineering

DOI

doi.org/10.1002/pen.22001

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