2.1 Reinforcing Effect
17
NR (see 8.1) may be larger than 100 nm. NR latex is a kind of emulsion in vivo,
biochemically produced in Hevea brasiliensis [4, 8, 12, 23–25]. The size distribution
of the rubber particle in the NR latex, in which NR is biosynthesized, is widely
ranging between 5 nm and 3 µm [24]. Dispersion phase of TPE which is functioning
as cross-linking point is between a few tens nm and 1 µm. In ordinary rubber blends,
the dispersion phase is ranging a few µm and 1 mm or so. The macroscopic bodies
in our environment are usually larger than 1 mm in size.
In all cases, Fig. 2.2 shows the approximate size range. Please check this figure
when you encounter any structural issue during your study on rubber reinforcement.
Comparison of the size ranges of the structure factors helps us to have insight into the
relationship between or among the structures. It is noteworthy that CB and particulate
silica, the crystallite, and the dispersion phase of TPE are all of submicron meter size.
They are reinforcing for rubber, which suggests that their nm size matters for rubber
reinforcement.
2.2 Compounding Reagents for Rubber
Historically, rubber had been a strange and curious material for long [1–3, 25–
31]. Hence, lots of street inventors who were interested in it were working on the
mixing with anything (often powdery solids and sometimes liquids of high-boiling
point) to prepare a soft and stretchable material of use. This trend continued during
the early stage of modern times, that is, after the introduction of NR to Europe
in the seventeenth century up to the end of eighteenth century. The invention of
vulcanization by C. Goodyear (1800–1860) in 1839 was a breakthrough, which
might have led the primitive rubber technics to the next advanced stage. However,
Goodyear, who was one of such back-street inventors, had failed to recognize the
vulcanization as a chemical reaction. Considering the developmental stage of modern
chemistry then, the failure was not his mistake at all. After his trials of hundreds or
thousands of reagents, he found out sulfur and white lead to have induced a kind of
change by chance, which transformed a raw rubber to a stable elastic material. The
keen intelligence of Goodyear is not much scientific, but it is his highly instinctive
recognition that what the vulcanization has brought about to raw rubber is quite
different from all the other inventors observed so far by heating of so many kinds of
rubber compounds [2, 12, 14, 15, 25–30].
Elucidation of the nature of vulcanization (a complex chemical reaction between
sulfur and rubber) was not initiated until the twentieth century [12, 14, 15, 31, 32].
After listing the experimental results, Weber wrote in his book [31] at p. 89,
The above conclusively settles the question regarding the general chemical aspect of the
vulcanisation process, but it confronts us with the further question respecting the quantity of
sulphur combining with India rubber in this process, as well as the more intimate structure
of the compound thus formed.
17
NR (see 8.1) may be larger than 100 nm. NR latex is a kind of emulsion in vivo,
biochemically produced in Hevea brasiliensis [4, 8, 12, 23–25]. The size distribution
of the rubber particle in the NR latex, in which NR is biosynthesized, is widely
ranging between 5 nm and 3 µm [24]. Dispersion phase of TPE which is functioning
as cross-linking point is between a few tens nm and 1 µm. In ordinary rubber blends,
the dispersion phase is ranging a few µm and 1 mm or so. The macroscopic bodies
in our environment are usually larger than 1 mm in size.
In all cases, Fig. 2.2 shows the approximate size range. Please check this figure
when you encounter any structural issue during your study on rubber reinforcement.
Comparison of the size ranges of the structure factors helps us to have insight into the
relationship between or among the structures. It is noteworthy that CB and particulate
silica, the crystallite, and the dispersion phase of TPE are all of submicron meter size.
They are reinforcing for rubber, which suggests that their nm size matters for rubber
reinforcement.
2.2 Compounding Reagents for Rubber
Historically, rubber had been a strange and curious material for long [1–3, 25–
31]. Hence, lots of street inventors who were interested in it were working on the
mixing with anything (often powdery solids and sometimes liquids of high-boiling
point) to prepare a soft and stretchable material of use. This trend continued during
the early stage of modern times, that is, after the introduction of NR to Europe
in the seventeenth century up to the end of eighteenth century. The invention of
vulcanization by C. Goodyear (1800–1860) in 1839 was a breakthrough, which
might have led the primitive rubber technics to the next advanced stage. However,
Goodyear, who was one of such back-street inventors, had failed to recognize the
vulcanization as a chemical reaction. Considering the developmental stage of modern
chemistry then, the failure was not his mistake at all. After his trials of hundreds or
thousands of reagents, he found out sulfur and white lead to have induced a kind of
change by chance, which transformed a raw rubber to a stable elastic material. The
keen intelligence of Goodyear is not much scientific, but it is his highly instinctive
recognition that what the vulcanization has brought about to raw rubber is quite
different from all the other inventors observed so far by heating of so many kinds of
rubber compounds [2, 12, 14, 15, 25–30].
Elucidation of the nature of vulcanization (a complex chemical reaction between
sulfur and rubber) was not initiated until the twentieth century [12, 14, 15, 31, 32].
After listing the experimental results, Weber wrote in his book [31] at p. 89,
The above conclusively settles the question regarding the general chemical aspect of the
vulcanisation process, but it confronts us with the further question respecting the quantity of
sulphur combining with India rubber in this process, as well as the more intimate structure
of the compound thus formed.