科研之友
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摘要
Rheological and conductivity measurements are reported to investigate the dispersibility of graphitic carbon black dispersions selected as a model for carbon nanotubes. The effectiveness of three dispersants in nonpolar organic solvents were investigated namely polyhydroxystearic acid (Hypermer LP1), PEG 30-dipolyhydroxystearate (Hypermer B246), and polyisobutylene succinimide (OLOA 11000). Hypermer LP1 is homopolymer and Hypermer B246 is polyhydroxystearic acid/polyethylene oxide/polyhydroxystearic acid ABA block copolymer while OLOA 11000 has polar head group (polyamine) attached to a hydrocarbon chain (polyisobutylene). Two nonpolar organic solvents decalin and xylene were selected for the present work. The experimentally determined relative viscosity as a function of effective volume fraction phi curves were compared with the theoretical curves calculated using Kreiger-Dougherty equation for the hard sphere dispersions. The comparison showed that Hypermer B246 and OLOA 11000 dispersions in xylene could be prepared at somewhat higher solid fraction than those dispersions stabilized by Hypermer LP1. Also Hypermer LP1 dispersions do not agree with the Kreiger-Dougherty equation curve, which showed that Hypermer LP1 is not an effective stabilizer. In oscillatory measurements, high values of storage and loss modulus at high volume fractions were obtained indicating strong repulsive interactions between the carbon black particles using Hypermer B246 and OLOA 11000. The dispersions prepared using these surfactants showed lower electrical conductivity as compared to other dispersions prepared without dispersants. Also higher relative conductance was obtained in case of dispersions made by Hypermer LP1 as compared to other dispersions made by Hypermer B246 and OLOA 11000. <graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ldis_a_683978_o_uf0001.jpg"></graphic
- 出版日期2013-5-1
