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

5.3 Results and Discussion
5.3.1 Cure characteristics
Use of nano zinc oxide in chloroprene rubber
Table 5.2 Torque values of gum and filled compounds
Property C – 1 C – 2 C – 3 C-4 C – 5 C – 6 C – 7 C-8 C –9 C- 10
Min torque (dNm) 0.163 0.177 0.177 0.182 0.506 0.402 0.333 0.385 0.297 0.235
Max torque (dNm) 2.605 2.713 2.707 2.48 6.041 5.964 6.240 5.32 4.835 5.423
∆Torque (dNm) 2.442 2.536 2.530 2.29 5.535 5.562 5.907 4.93 4.538 5.188
Torque values of gum and filled compounds with ZnO(c), ZnO(p) and
ZnO(s) are shown in Table 5.2. Compared to the torque values of filled and
gum CR compounds with 2phr and 5phr conventional ZnO, it is found that
compound with 5phr conventional ZnO (C-1) shows better torque values
than compound with 2phr conventional ZnO compound (C-4).
The torque values of filled and gum CR compounds, with 2phr
ZnO(p) and 2phr ZnO(s) are equivalent with the torque values of compounds
with 5phr ZnO(c). Comparing the torque values of C– 6, C– 7, C– 9 and C–10,
the torque values of C-6 and C-7 compounds are better than the torque values
of C-9 and C-10 compounds. So 2phr ZnO(p) and 2phr ZnO(s) are selected as
the optimum dosage of compounds that can give better reinforcement
compared to 1phr ZnO(p) and 1phr ZnO(s).
Table 5.3 Cure behaviour of gum and filled compounds
Property C– 1 C– 2 C– 3 C-4 C- 5 C– 6 C-7 C-8 C-9 C-10
Scorch time
(tS2),min
Optimum cure time
(t90), min
Cure rate index
(100/t90– tS2)
12.96 12.67 12.96 14.60 4.02 4.53 4.36 4.03 3.98 3.58
17.53 17.04 17.26 19.80 19.29 19.70 19.60 22.41 20.31 21.12
21.88 22.88 23.25 19.20 6.54 6.59 6.56 5.44 6.12 5.70
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