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

Use of nano zinc oxide in chloroprene rubber
density values of the composite with 5phr conventional ZnO. The crosslink
densities of C-6 and C-7 vulcanizates are superior to that of C-5 vulcanizate.
Swelling resistance in solvents and oil
Swelling resistance of gum and filled composites in different solvents
and in engine oil are shown in Table 5. 10.
Solvent
Table 5.10 Swelling index value of composites
Swelling index (%)
C-1 C-2 C-3 C-5 C-6 C-7
Cyclohexane 86 85 83 43 43 41
Petrol 53 52 52 26 27 25
Diesel 39 39 39 24 25 23
Engine Oil 41 41 38 26 28 24
Several researchers have extensively studied the transport behavior of
various organic liquids in polymer composites. 11,12 The phenomenon of
transport of liquids through rubbers is controlled by the polymer structure,
its crosslink density, presence of fillers, penetrant, size etc. It is clear from the
table that the swelling index values of C-2 and C-3 gum vulcanizates are
comparable to C-1 gum vulcanizate and the swelling index values of C-6 and
C-7 filled vulcanizates are comparable with C-5 filled vulcanizate. This
indicates C-2, C-3 and C-6, C-7 vulcanizates with lower dosage of ZnO show
equivalent swelling property to that of C-1 and C-5 vulcanizates with higher
dosage of ZnO respectively.
5.3.5 Thermal ageing
Ageing resistance of the composites with 2phr ZnO(p), ZnO(s) and
5phr ZnO(c) were measured by measuring the tensile properties after ageing
to 72 hrs at 100°C and is given in the Table 5.11.
100