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

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Chapter 8<br />

acid <strong>and</strong> heated until boiled for 30 m<strong>in</strong>utes. Then <strong>the</strong> mixture was ma<strong>in</strong>ta<strong>in</strong>ed<br />

at 105°C for 3 hours. Dur<strong>in</strong>g this step, <strong>the</strong> color <strong>of</strong> <strong>the</strong> husk gradually changed<br />

from yellow to dark brown. After <strong>the</strong> reacti<strong>on</strong>, <strong>the</strong> acid was completely<br />

removed from <strong>the</strong> husk by wash<strong>in</strong>g with tap water. It was <strong>the</strong>n dried<br />

overnight <strong>in</strong> an oven at 110°C. The treated husk was burnt <strong>in</strong> an electric<br />

furnace by c<strong>on</strong>troll<strong>in</strong>g <strong>the</strong> temperature so that it reached 600°C <strong>in</strong> <strong>on</strong>e hour.<br />

After burn<strong>in</strong>g at 600°C for 6 hours, <strong>silica</strong> was obta<strong>in</strong>ed <strong>in</strong> <strong>the</strong> form <strong>of</strong> white<br />

ash. The shape <strong>of</strong> <strong>the</strong> <strong>silica</strong> is similar to <strong>the</strong> shape <strong>of</strong> <strong>the</strong> husk, but smaller <strong>in</strong><br />

size. It was <strong>the</strong>n gr<strong>in</strong>d to f<strong>in</strong>e powder to get <strong>silica</strong> <strong>in</strong> smaller particle size.<br />

162<br />

(a) (b) (c)<br />

Figure 8.6 (a) rice husk (b) rice husk after treatment with acid (c) RH<strong>silica</strong><br />

Preparati<strong>on</strong> <strong>of</strong> antioxidant <strong>modified</strong> RH<strong>silica</strong><br />

1phr <strong>of</strong> antioxidant (IPPD) was mixed with 50phr <strong>of</strong> RH<strong>silica</strong> <strong>in</strong><br />

torque rheometer (brabender plasticorder) at 50 rpm, 80°C for 5 m<strong>in</strong>utes.<br />

Rubber compound<strong>in</strong>g<br />

The natural rubber was compounded with antioxidant <strong>modified</strong><br />

RH<strong>silica</strong> <strong>and</strong> neat RH<strong>silica</strong> <strong>on</strong> a laboratory two roll mix<strong>in</strong>g mill (16 x 33 cm)<br />

as per <strong>the</strong> formulati<strong>on</strong> given <strong>in</strong> Table 8.6.

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