Semi-reinforcing black

Most furnace black reactors are arranged horizontally. They can be up to 18 m long with an outer diameter of up to 2 m. Some vertical reactors are used especially for the manufacture of certain semi-reinforcing blacks (Figure 4.5) [4.12]. Further reactors are described in Ref. [4.13]. 

Carbon blacks are usually used as fillers. The semi-reinforcing types, such as PEP (Past Extmsion Pumace) and SRE (Semi-Reinforcing Pumace) give the best performance (see Carbon, carbonblack). To lower the cost and improve the processibiUty of light compounds, or to lower the cost of black compounds, calcined clay or fine-particle calcium carbonate are used. 

N762 (Semi-Reinforcing Furnace) Carbon Black — 7... 

N762 (semi-reinforcing furnace) carbon black — 7... 

The proven compounding practice for the natural rubber layer is to load it with 30 phr of graphite, 30 phr of semi-reinforcing carbon black filler and 50 phr of inert filler, china clay. A low sulfur curing system is adopted for heat resistance with a suitable antioxidant to prevent flex-cracking. A typical chlorine resistant soft natural rubber compound formula is given in Table 3.2. 

Without carbon black With 50 phr (semi reinforcing furnace black (SRF)... 

Filler Semi Reinforcing Furnace Carbon Black ... 

Semi-reinforcing carbon black SRF N762 Oil furnace 110 27 Medium reinforcement, high elongation and resilience, low compression set, used in mechanical goods, footwear, inner tubes and floor mats. 

Fig. 7.3. Effect of carbon black fillers on properties of a mi liable polyurethane elastomer. MT= Medium Thermal Carbon Black, SRF= Semi-Reinforcing Carbon Black, HAF= High Abrasion Furnace Carbon Black, ISAF= Intermediate Super Abrasion Furnace Carbon Black.

The barrier properties of 70/30 acrylonitrile-butadiene mbber/ethylene propylene diene monomer rubber (NBR/EPDM) vulcanizates, when loaded with carbon black fillers [e.g., I SAP (intermediate super-abrasion furnace), HAF (high-abrasion furnace) and SRF (semi-reinforcing furnace)] and using benzene, toluene and xylene as penetrants, have been examined with reference to the type of filler employed [66]. The filled samples were found to exhibit a better resistance to uptake of the three organic solvents when compared to the respective unfilled blends for any given blend ratio. With regards to the three types of carbon black used, solvent uptake was in the order SRF-> HAF-> ISAF-filled samples. The reason for this order was attributed to the better filler reinforcements and enhanced crosslink densities of the matrix as the size of the carbon black particles used was decreased. A similar behavior was also identified for NR/EVA composites [52]. 

The anisometry (platelet shape) and particle size of the clays account for their affect on modulus and hardness. More hard clay than soft is used in rubber because of its semi-reinforcing effect and its utility as a low cost complemenent to other fillers. It is used to improve the tensile and modulus of ground calcium carbonate eompoimds and will substitute for a portion of the more expensive carbon black or precipitated silica in certain compounds without sacrificing physical properties. 

A Chinese study [7] has involved subjecting PCB to demineralisation and then surface modification with a titanium coupling agent (NDZ-105), and then investigating how the black interacted with polyisoprene molecules by inverse gas chromatography. Rubber compounds were also prepared using these modified blacks and their mechanical properties were recorded. The results indicated that these blacks could be used to replace commercial semi-reinforcing carbon blacks in rubber compounds. 

SRF-HS Semi-reinforcing furnace black (high structure)... 

---