Effect of Functionalization of Carbon Black on Rubber Properties

Table I. Analytical properties <strong>of</strong> the fillers
Si content % BET-SA, m2 /g STSA, m2/g CDBP I2 No.
Silica
coveragea TMCS
uptake
Filler As is HF As is HF As is HF mL/100g mg/g % #/nm 2
N134 N/A N/A 146 N/A 134 N/A 104 143 N/A N/A
N234 N/A N/A 122 122 118 118 100 120 N/A 0.02
CSDPF CRX2124 4.1 0.85 171 251 133 146 115 120 9 0.32
CSDPF CRX4210 10.0 0.01 154 167 123 155 108 62 55 1.04
Silica Z1165 46.7 N/A 168 N/A 132 N/A N/A NA 100 2.02
a. The silica-surface coverage <strong>of</strong> CRX2124 was estimated from silicon content and that <strong>of</strong> CRX4000
was from iodine number and surface area which was the averaged value <strong>of</strong> BET-SA and STSA.
b. Number <strong>of</strong> TMCS uptake per nm 2 estimated using averaged surface areas from BET-SA and STSA
is referred to as CSDPF 4000 family corresponding to CRX4XXX group. In this paper,
we will first describe the features <strong>of</strong> CSDPF 2000 and 4000 with regard to their analytical
characteristics and in-rubber properties, and then discuss the applications <strong>of</strong> CSDPF 4000
to passenger tire tread compounds and CSDPF 2000 to truck tire tread compounds, taking
CRX4210 and CRX2124 as examples, respectively.
The features <strong>of</strong> CSDPF 2000 and CSDPF 4000 Series
Shown in Table I are the basic properties <strong>of</strong> CSDPF 2000 and 4000 compared with those
<strong>of</strong> conventional fillers. While both new materials contain silica, some <strong>of</strong> the differences
between CSDPF 2000 and 4000 include their distribution <strong>of</strong> silica, silica-surface
coverage and silicon content. CSDPF 4000 has much higher silica-surface coverage
relative to CSDPF 2000 which is due to the silica domain distribution and high silicon
content. This can be seen from the changes in silica content and surface area upon
hydr<strong>of</strong>luoric acid (HF) extraction. During HF extraction, the silica will be dissolved with
the carbon domain remaining unchanged. The fact that significant portions <strong>of</strong> silica still
remains, and surface areas drastically increase upon HF treatment <strong>of</strong> CSDPF 2000,
suggest that the silica <strong>of</strong> CSDPF 2000 is distributed throughout the aggregates. By
contrast, in the case <strong>of</strong> CSDPF 4000, the small change in surface areas and the fact that
there is almost no silica left after HF extraction indicate that the silica in the CSDPF 4000
aggregates is located on the surface. This observation is supported by the images and the
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b