Comparison of Ketjenblack EC Compounds and other Conductive Carbons

摘要

Data has been acquired that illustrate the variability in the surface chemical properties of a range of competitive conductive carbon black materials. Surface chemical properties play a great role in the dispersion and performance of conductive fillers. For this study, Ketjenblack~R EC 300J, Ketjenblack~R EC 600JD, Ketjenblack~R EC-X from Akzo Nobel (Ref. 1) and other competitive materials such as Ensaco~R (250, 350) from Erachem (MMM Corporation), Printex~R XE-2 from Degussa Corporation and Denka~R black (a type of acetylene black) materials were selected. Several analytical techniques such as ICP, XPS, XRD and IR were employed to understand differences in the surface chemistry of these additives in addition to structural and chemical analyses. These analyses included the neat powdered products as well as TPO plaques loaded with three weight percent of the conductive materials. Microscopic investigation has shown a range of dispersion types depending upon the carbon black material. Significant results include the following findings: 1. A good inverse correlation is indicated for conductive performance of these carbon blacks v/s. the degree of crystallinity. Lower crystallinity is desirable for better conductive performance as seen with Ketjenblack~R EC 300J, Ketjenblack~R EC-X and Ketjenblack~R EC 600 JD. Denka~R Black and Ensaco~R 250 possess significantly greater crystallinity than the other materials. Printex~R XE-2 was found to be in the middle of the range for crystallinity. 2. High metal impurities are considered detrimental for certain electroconductive applications, such as in wire and cable. All of Ketjenblack~R EC products were found to be containing low metal impurities. Whereas, Printex~R XE-2 was exceptionally high in light and transition metals compared to the other 6 samples. 3. A presence of low levels of oxygen functionality is desirable for low volatile content in conductive carbon and improved conductivity. All materials have low levels of incorporated oxygen functionalities. However, Denka~R Black has the highest observed oxygen content of 1.2 atom percent. Results of surface derivatization experiments by using XPS technique shows presence of R-OH, R-COOH and >C=O groups in all products. 4. Atomic Force Microscopy (AFM) examination of carbon black loaded TPO polymer discovered for the first time the preferential segregation of Ketjenblack EC products to the rubber phase. 5. Results of the AFM analyses of TPO samples containing the conductive carbons also indicate that Ketjenblack~R EC 600JD has higher affinity for elastomeric phase than Ensaco~R 250. In this case, better dispersion is seen for Ketjenblack~R EC 600 JD v/s Ensaco~R 250 at same loading levels.