Reactive processing of silica-reinforced tire rubber : new insight into the time- and temperature-dependence of silica rubber interaction
Mihara, Satoshi (2009) Reactive processing of silica-reinforced tire rubber : new insight into the time- and temperature-dependence of silica rubber interaction. thesis.
|Abstract:||In recent years, silica has become one of the most important fillers used in tire
tread compounds due to its contribution to a better environment. Silica is capable
of not only reducing the rolling resistance but also improving the wet skid
resistance of tires, compared to carbon black as a filler. However, silica-filled
compounds provide many difficulties during rubber processing, because of the
polarity difference between silica and polymer. To overcome these polarity
differences a bi-functional silane coupling agent is generally used. A typical silane
coupling agent is bis-(triethoxysilylpropyl)tetrasulfide (TESPT).
The silane chemistry during rubber processing is very complicated. Basically, from
a processing point of view, two coupling reactions take place via TESPT. The first
reaction is a coupling reaction between the TESPT molecule and the silica surface,
the so-called silanization reaction. For this reaction hydrolysis of TESPT is required.
The second reaction is silane-rubber coupling, supposed to happen only during the
vulcanization stage. However, it is well known that TESPT acts as a sulfur donor
during rubber processing. Therefore, premature crosslinking or scorch may take
place at excess temperatures in the mixing stage already. All these reactions can
take place simultaneously during silica rubber processing, and therefore the
reinforcing mechanism of silica is much more complicated than that of carbon
Diphenylguanidine (DPG) greatly contributes to the physical properties of silica
filled rubber. DPG acts as a secondary accelerator but also as silanization
accelerator. In addition, DPG is capable of interacting with the silica surface.
Therefore, DPG also affects the reinforcement effect of silica in rubber. DPG is
subject to toxic concerns and has a negative influence on rubber-metal adhesion.
Therefore, in the future DPG-alternatives will be required.
The first objective of the present thesis was to understand the reinforcing
mechanism of different types of silica in rubber. Especially, the focus was on the
bound rubber layer between silica and polymer, which significantly contributes to
the physical properties of silica filled rubber. The second objective was to unravel
the role of DPG played in silica-reinforced tire rubbers and the search for less toxic
or environmentally friendly alternatives.
Engineering Technology (CTW)
|Link to this item:||http://purl.utwente.nl/publications/61145|
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