Copyrighted material licensed to BR Demo by Thomson Reuters ( TS 62607-2-1@IEC:2012(E) - 11 - 4.2.2 Experimentalproceduresandmeasurementconditions I+ V+ V- 1 CNT Ribbon tt W L (Scientific), Inc., Key L=Spacing between adjacent probes t = thickness of CNT ribbon W = width of CNT ribbon. Figure4-Diagramfor 4-wiremeasurement apparatus A convenient fixture for resistance measurements is shown in Figure 4. Perpendicularly fix the 4Pt (platinum)wires with 0,1mm diameter onto an insulating substrate with L=3mm spacing between each wire. Place the specimen onto the electrodes to make electrical contact without damaging the specimen. Apply a low current (maximum 1μA) for the measurementinordertoavoiddamagetothesample. 5 Dataanalysis/Interpretationof results 5.1 Sheetresistanceof SwCNTsorMwCNTsusing4-pointmeasurements Calculate sheet resistanceusing 4-pointmeasurementsas follows: (1) Where: Rs = sheet resistance, V = measured voltage No further reproduction or distribution is permitted. = applied current, VII = the gradient of a plot of Vversus I, and F = geometrical correction factor [9,10] In the case when the sample size is much larger than the spacing between the electrodes's' [9].For example, results with better than 99 %accuracy can be obtained bymeasuring in the centre of a circle with a diameter greater than 40 s; and results with better than 1 % error can 5.2 SheetresistanceofSwCNTsorMwcNTsusing4-wiremeasurements Calculate sheet resistance in 4-wire measurements as follows: Uncontrolled when wVV Rs: (2) prin Copyrighted material l - 12 - TS 62607-2-1@ IEC:2012(E) I icensed to BR Demo by Thomson Reuters ( Where: Rs = sheet resistance, V =measured voltage, 1 = applied current, VII = the gradient of a plot of V versus I, w = specimen width measured using a calibrated optical microscope,and 7 = distance between wires. (Scientific), Inc., , subscriptions.techstreet.com, , downloaded on Nov-28-2014 by James Madison. No further r reproduction or distribution is permited. Uncontrolled when print - 13 - TS 62607-2-1 @ IEC:2012(E) licensed to BR Demo by Thomson Reuters ( Annex A (informative) Case study A.1 Sample preparation A.1.1 Single-wall andmultiwall carbon nanotubes(SwCNTs and MwCNTs) SWCNTs wereobtained from2 different manufacturers.MWCNTs were obtained from 3 different manufacturers. The CNTs in the as-received condition were used for this entire test. (Scientific), Inc., A.1.2 Choice of dispersant The organic dispersants used to disperse the CNTs were DMF,THF,and 1,2-DCE.Among of proper handling and dispersability. THF provides a well-dispersed CNT suspension, minimizes CNT surface damage during the sonication step,and dries rapidly to make a thin film. The properties considered in the selection of the best dispersant used to disperse CNTs and prepare thin-film samples are summarized in Table A.1. .com. TableA.1-Properties of dispersants used to preparethin-film samples. THF DMF 1,2-DCE Varied by Dispersion of CNTs Good Good types of NTs Effect on electronic Effect structure of CNTs during Effect No effect [7] (strong chemical disruption of the ultrasonic treatment in (Cl, or HCI doping) [12] bonding of nanotubes) [11] dispersant Speed of evaporation Fast Very slow Fast A.2 DeterminationofquantityofSwCNTsand/orMwCNTs No further To determine a quantity of CNT to produce a CNT film of uniform thickness, it was tested that a specified quantity of CNTs dispersed in a predetermined volume of dispersant. When 1 mg of SWCNTs or MWCNTswas used,filmthicknesses varied widelybetween10 μm and50 μm. The film thickness was relatively well-controlled to (90 ± 5)μm with a quantity (mass) of 5 mg, but the film became fragile, especially when mechanical force was applied to make the ribbon forms.2mg of SWCNTs or MWCNTs produced the most uniform film ((5o ±1)μm) with homogeneously-bundled SwCNTs or MwCNTs,and were robust in the ribbon shape forthe purpose of 4-probe measurements.From the results,it proposed that 2 mg of CNTs is a suitabl