Rubber carbon black properties

These studies have dealt with materials suitable for fuel and feedstocks, the process for converting these materials to carbon black with predictable properties, the techniques for measuring and defining those properties, a better understanding of the effects of those carbon black properties on processing parameters of compounded goods, and the predictability of the performance properties of finished rubber goods. This presentation briefly considers the status of each of these areas of study relative to today s carbon blacks and tomorrow s rubber products. 

Owing to the different mechanical properties, filler particles can be in most cases differentiated from the polymeric matrix in SFM. Examples include carbon black or silica-filled rubbers, carbon-black-filled polymer blends or salt-loaded block copol5nner micelles. For the latter case, Spatz and co-workers demonstrated... 

Unfortunately the raw materials used in compounding are, as in any other production, not uniform in all respects. Materials from different sources can have slightly changed properties, rubbers, carbon blacks and fillers being particularly subject to variation. 

Traditionally, as a filler of rubber carbon black is used. It is an active filler able to reinforce and improve the properties of finished rubber products. For ecological and economic reasons this filler has many disadvantages i.e. on the filler surface the hydrocarbon rings are present, also the methods of carbon black production from petrochemical sources is environmental unfriendly. Nowadays the research activity is focused on looking for new methods of surface modification of inactive fillers to enhance their strengthening performance in elastomers. 

In detail, the fast recovery is clearly related to the surface area and the structure of carbon black, the larger the surface areas by nitrogen absorption (see Chapter 9) and the lower the structure by dibutyl phthalate (DBF) absorption (see Chapter 9) the larger is the swell. The slow recovery was not clearly related to the carbon black properties. What causes the fast and slow recovery is the subject of future study. The fast recovery may primarily be related to the deformation of carbon black network and the slow recovery to the deformation of the rubber matrix. 

H.J. Song, J.L. White, K. Min, N. Nakajima, F.C. Weissert. Rheological properties, extrudate swell, and die extrusion flow marker experiments for rubber carbon black compounds. Adv. Polym. Technol, 8,421-449,1988. 

Table 3. Properties of Carbon Black-Filled Natural Rubber Vulcanizates With Various Cure Systems ...

Rubber. The mbber industry consumes finely ground metallic selenium and Selenac (selenium diethyl dithiocarbamate, R. T. Vanderbilt). Both are used with natural mbber and styrene—butadiene mbber (SBR) to increase the rate of vulcanization and improve the aging and mechanical properties of sulfudess and low sulfur stocks. Selenac is also used as an accelerator in butyl mbber and as an activator for other types of accelerators, eg, thiazoles (see Rubber chemicals). Selenium compounds are useflil as antioxidants (qv), uv stabilizers, (qv), bonding agents, carbon black activators, and polymerization additives. Selenac improves the adhesion of polyester fibers to mbber. 

Table 7. Typical Properties Rubber-Grade Carbon Blacks ...

D-TEM gave 3D images of nano-filler dispersion in NR, which clearly indicated aggregates and agglomerates of carbon black leading to a kind of network structure in NR vulcanizates. That is, filled rubbers may have double networks, one of rubber by covalent bonding and the other of nanofiller by physical interaction. The revealed 3D network structure was in conformity with many physical properties, e.g., percolation behavior of electron conductivity. 

---