Powder Processing and Properties Characterization of Polyamide 11- Graphene Nanocomposites for Selective Laser Sintering

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Date

2010

Authors

Chen, D.Z.
Lao, S.
Koo, J.H.
Londa, M.
Alabdullatif, Z.

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University of Texas at Austin

Abstract

Nano-graphene platelets (NGPs) were added to polyamide 11 (PA11) powder in 1%, 3%, and 5% weight loading in an attempt to create electrostatic dissipative polymer nanocomposites (PNC) using SLS, a rapid manufacturing process. Powder-powder mixing techniques were explored as a potential replacement for twin-screw extrusion for dispersing nano-graphene platelets (NGPs) within a PA11 matrix. The Resodyn™ Resonant Acoustic Mixer as well as the Thinky™ mixer were studied as powder-powder mixing techniques. After mixing, the powder samples were pressed into thin-films for characterization on TGA, SEM, four-probe conductivity, and Raman spectroscopy. TGA results indicate a slight decrease in thermal stability with the addition of NGPs. This suggests an inadequate dispersion of NGP within the polymer matrix. SEM images support this hypothesis with evidence of artifacts, a sign of electron charging, as well as clusters of NGPs. The four-probe conductivity measurements indicate that all of the samples studied exceed the sensitivity range of the machines used, which is estimated to be 4.5x1010 Ω/=. This indicates that all of the samples are at least in the upper region of the range for electrostatic dissipation, if not out of it entirely. Further research will include twin-screw extrusion as well as surface functionalization of NGPs for better dispersion.

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