4. Conclusions
The influence of variation of oil and zinc oxide type on the gas
barrier and mechanical properties of a blend of chlorobutyl rubber
and epoxidised natural rubber was studied in details. In this blend
of (90:10 = CIIR:ENR) the use of 5 phr of refined aromatic extract
(RAE) oil along with 5 phr of sheet zinc oxide was found to be
the best formulation to achieve overall balance of excellent gas
barrier and good mechanical properties. The use of RAE was further
beneficial because it contains fewer amount of polycyclic aromatic
hydrocarbons (PAHs) compared to A#2 aromatic oil, thus, rendering it noncarcinogenic and more eco friendly. The sheet zinc oxide
offered maximum resistance to oxygen permeation because it generated maximum surface area per unit weight compared to other
classes of zinc oxide used in this particular study.
In the study, the arbitrary lower limit of elongation at break and
ultimate tensile strength was taken as 300% and 10 MPa respectively, while the upper limit of oxygen permeability was fixed at
3.5 in the respective unit. Following these arbitrary limits, the
validities of the compoundings were judged. It was found that in
the case of sheet zinc oxide, the elongation at break was 430%.
It is noteworthy to mention that a future work by the authors is
targeted to increase the value of elongation at break to above 500%,
keeping the other required parameters intact.