1.2 Carbon Black-Loaded Natural Rubber Vulcanizate …
5
soot), and the sale of their product by the channel method experienced a sudden
increase in the 1910s. What happened, then?
Early in the twentieth century, the CB-loaded vulcanizate of natural rubber (NR)
was reported by S. C. Mote (1867–1944) to be of value in manufacturing a rubber
tire in combination with fiber materials [13]. His patent in 1904 (to Silvertown Co.
in England) referred to the use of CB and NR mixture, but its main claim was not on
CB/NR mix but on NR composites with a fiber cord for automobile tires. In 1910, the
Diamond Rubber Co. of New York, whose factory was at Akron, took out a license
to manufacture and sell this tire in the USA. This business was acquired in 1912 by
B. F. Goodrich, who later sponsored a full-page advertisement (Boston Sunday Post,
May 14, 1916) as follows:
Without the strength, endurance and enormous mileage-power of these genuine Silvertown
Cord Tires, the recent racing speed for 350 miles of 102 miles per hour average, would have
been impossible.
The Cord Tires which were manufactured from CB/NR mix combined with fiber
cords did give rubber tires of excellent performance as advertised [13]. Here ‘two
new factors’ may be recognized in the rubber composite: First NR was mixed with
CB, and secondly, the rubber mix was further combined with fiber cords. The first
has afforded excellently reinforced NR compounds, which is the origin of rubbers
compounded with CB or any other nanofiller in general. The selection of CB, in
particular, by Mote was a uniquely amazing finding. Even though there had been
tried so huge number of additives, both inorganic and organic, since the invention of
vulcanization by Goodyear in 1839, CB had not been much mentioned specifically.
Goodyear himself was one of such inventors to find sulfur a key material: Note
that he did not think the vulcanization was a chemical reaction at all. It was quite
possible that someone had tried CB mixing into rubber before Mote, but had failed
to recognize any specific affinity of CB with rubber.
Mote’s selection of CB might suggest his insight into the nature of rubber; rubber
is apparently solid, but it is liquid-like due to the segmental micro-Brownian movement of rubber [3, 12, 14]. In mixing a solid (CB) into a liquid (rubber), affinity
or compatibility between the two is an important factor to get a good solution. H.
J. Stern, the author of Ref. [13], checked the CB content of the remaining Mote’s
original rubber compound, and reported that it was 23%. This value is approximately
comparable to 30 phr of CB, which is the range still used in many rubber formulations (The phr designates parts per hundred rubber by weight.). The CB used by
Mote was a channel carbon (the words ‘gas carbon’ is also used, since natural gas is
the raw material), not a furnace carbon. But, the difference of their specific gravity
is not so much to negate the semiquantitative comparison shown above. CB has still
remained the prime reinforcing agent in the rubber industry. His finding has given us
the first part of the standard rubber formulation rule, i.e., selection of a suitable filler
at the first step, which has much helped rubber engineers in their design of rubber
products, so far.
5
soot), and the sale of their product by the channel method experienced a sudden
increase in the 1910s. What happened, then?
Early in the twentieth century, the CB-loaded vulcanizate of natural rubber (NR)
was reported by S. C. Mote (1867–1944) to be of value in manufacturing a rubber
tire in combination with fiber materials [13]. His patent in 1904 (to Silvertown Co.
in England) referred to the use of CB and NR mixture, but its main claim was not on
CB/NR mix but on NR composites with a fiber cord for automobile tires. In 1910, the
Diamond Rubber Co. of New York, whose factory was at Akron, took out a license
to manufacture and sell this tire in the USA. This business was acquired in 1912 by
B. F. Goodrich, who later sponsored a full-page advertisement (Boston Sunday Post,
May 14, 1916) as follows:
Without the strength, endurance and enormous mileage-power of these genuine Silvertown
Cord Tires, the recent racing speed for 350 miles of 102 miles per hour average, would have
been impossible.
The Cord Tires which were manufactured from CB/NR mix combined with fiber
cords did give rubber tires of excellent performance as advertised [13]. Here ‘two
new factors’ may be recognized in the rubber composite: First NR was mixed with
CB, and secondly, the rubber mix was further combined with fiber cords. The first
has afforded excellently reinforced NR compounds, which is the origin of rubbers
compounded with CB or any other nanofiller in general. The selection of CB, in
particular, by Mote was a uniquely amazing finding. Even though there had been
tried so huge number of additives, both inorganic and organic, since the invention of
vulcanization by Goodyear in 1839, CB had not been much mentioned specifically.
Goodyear himself was one of such inventors to find sulfur a key material: Note
that he did not think the vulcanization was a chemical reaction at all. It was quite
possible that someone had tried CB mixing into rubber before Mote, but had failed
to recognize any specific affinity of CB with rubber.
Mote’s selection of CB might suggest his insight into the nature of rubber; rubber
is apparently solid, but it is liquid-like due to the segmental micro-Brownian movement of rubber [3, 12, 14]. In mixing a solid (CB) into a liquid (rubber), affinity
or compatibility between the two is an important factor to get a good solution. H.
J. Stern, the author of Ref. [13], checked the CB content of the remaining Mote’s
original rubber compound, and reported that it was 23%. This value is approximately
comparable to 30 phr of CB, which is the range still used in many rubber formulations (The phr designates parts per hundred rubber by weight.). The CB used by
Mote was a channel carbon (the words ‘gas carbon’ is also used, since natural gas is
the raw material), not a furnace carbon. But, the difference of their specific gravity
is not so much to negate the semiquantitative comparison shown above. CB has still
remained the prime reinforcing agent in the rubber industry. His finding has given us
the first part of the standard rubber formulation rule, i.e., selection of a suitable filler
at the first step, which has much helped rubber engineers in their design of rubber
products, so far.