Studies on the use of nano zinc oxide and modified silica in NR, CR ...

Chapter 2
roll with mill opening at 1.4 mm and was increased to 1.9 mm as the band
became smooth. The temperature of the rolls was maintained at 70±5 °C. The
compounding ingredients were added as per procedure given in ASTM D
3184–89 and ASTM D 3182–89 in the following order: activator, filler,
accelerator and curing agents. Before the addition of accelerator and sulphur,
the batch was thoroughly cooled.
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After mixing all the ingredients, homogenization of the compound
was carried out by passing the rolled stock end wise six times at a mill
opening of 0.8 mm. The mill was opened to give a minimum stock thickness
of 6 mm and the stock was passed through the rolls four times folding it back
on itself each time.
Mixing of the compounds using brabender plasticorder
Brabender plasticorder has been widely used for measuring
processability of polymer. The heart of the torque rheometer is a jacketed
mixing chamber whose volume is approximately 40 cc for the model used (PL
3S). Mixing and shearing of the material in the mixing chamber is done by
horizontal rotors with protrusions. The resistance put up by the test material
against rotating rotors in the mixing chamber is indicated with the help of a
dynamometer balance. The dynamometer is attached to a mechanical
measuring system, which records the torque. A dc thyrister controlled drive
is used for speed control of the rotors (0 to 150 rpm). The temperature can be
varied up to 300°C. A thermocouple with a recorder is used for temperature
measurements. Different type of rotors can be employed depending upon the
nature of the polymer used. The rotors can be easily mounted using the
simple fastening and coupling system. Mixing time and temperature were
controlled during the process.