Effect of Functionalization of Carbon Black on Rubber Properties

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Wet skid resistance: The results <strong>of</strong> wet skid resistance measured with BPST are illustrated in Figure 12 as a function <strong>of</strong> silica surface area per unit mass <strong>of</strong> the filler. This silica surface area is proportional to the silica-polymer interfacial area per unit volume <strong>of</strong> the compound at the same filler loading. The test was performed at room temperature, using a wet sandblasted glass plate as a path surface. It was found that the skid resistance increases linearly with the silica interfacial area in the compounds, regardless <strong>of</strong> the dynamic properties. Compared with carbon black and CSDPF 2000, due to the high silica-surface-coverage, CRX4210 gives significantly higher wet skid resistance. As mentioned previously, the EHL and BL are essential for wet skid resistance. Under the test condition <strong>of</strong> BPST, due to a very small contact length <strong>of</strong> the test pad with smooth glass in the sliding direction, the MEHL plays a dominant role in skid resistance. 4 It has also been recognized that for the SSBR/BR compound, while silica is very effective to reduce MEHL, carbon black is favorable to friction under BL condition. Therefore compared with carbon black and CSDPF, the higher BPST number <strong>of</strong> CRX4210 should be expected from its improved silica-coverage. Moreover, there is a good correlation <strong>of</strong> BPST numbers with peak friction values from road tests for passenger tire. 5 Thus, an improved wet skid resistance can be expected from CRX4210 for passenger tires equipped on the vehicle having ABS. This is because ABS operates near the peak. It should be pointed out that, the relative roles <strong>of</strong> the EHL and BL in wet skid resistance vary with test conditions. With increasing 115 110 105 100 95 BPST index, % OESSBR/BR 70/30, Filler: equal volume 0 20 40 60 80 100 120 14 CRX 4210 N234 CSDPF CRX 2214 CSDPF 4000 Silica Surface Area, m 2/g filler Figure 12. effect <strong>of</strong> silica surface area in fillers on wet skid resistance
oad surface roughness, decreasing vehicle speed, decreasing water film thickness, increasing load, and raising temperature, the importance <strong>of</strong> BL will increase. Therefore a better-balanced result would be expected in the road test for CRX4210 due to its hybrid surface and dynamic properties. In conclusion, when CRX4210 is used in passenger tire tread compounds to replace carbon black, the rolling resistance and wet skid resistance compromise will be significantly improved without significant trade-<strong>of</strong>f in treadwear, as in the case with silica. Application <strong>of</strong> CSDPF CRX2124 to tread compounds for truck tires Although silica has been successfully used with solution SBR and coupling agent in passenger tread compounds to improve rolling resistance and wet traction, the application <strong>of</strong> silica to truck tire compounds has not been successful. 9 This is mainly due to the poor treadwear which is related to its lower filler-polymer interaction. For heavy radial truck tire, NR is essentially the principle polymer in tread compounds. 10,11 Due to the high nonrubber content <strong>of</strong> the natural rubber and high polarity <strong>of</strong> the silica surface, the weak polymer-filler interaction is not well compensated for by the coupling agent, so that there is a significant deficiency in abrasion resistance. 12 Accordingly, CSDPF 2000, especially its higher surface area grade CRX2124, should be the best filler for NR-based truck tire Table III. Formulations for truck tire tread compounds NR (SIR-20) 100 100 100 <strong>Carbon</strong> black N134 50 - - CRX2124 - 50 50 TESPT - 1.0 - Oil (CircoLite) 2.5 2.5 2.5 Zinc Oxide 5.0 5.0 5.0 Stearic Acid 3.0 3.0 3.0 Antioxidant (AgeRite resin D) a 1.5 1.5 1.5 Antioxidant (Sant<strong>of</strong>lex 13) 1.5 1.5 1.5 Wax (Sunpro<strong>of</strong> Imp) 1.5 1.5 1.5 TBBS b 1.2 1.2 1.2 Sulfur 1.0 1.4 1.7 a. Polymerized 2,2,4,-trimethyl-1,2-dihydroquinoline.b. N-tert-butyl-benzothazole-2-sulfenamide. 15
Page 1 and 2: Effect of<
Page 3 and 4: carbon blacks to improve the trade<
Page 6 and 7: Table I. Analytical properties <str
Page 8 and 9: Before ashing After ashing Figure 4
Page 10 and 11: 12.0 10.0 8.0 6.0 4.0 2.0 0.0 Strai
Page 12 and 13: 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2
Page 17 and 18: compounds. With this filler, the hi
Page 19 and 20: 140 120 100 80 60 40 20 0 Wet skid

Effect of Functionalization of Carbon Black on Rubber Properties

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