ื1. Introduction
Tubes and inner liners of tubeless tires need to be under an
inflated condition for a reasonably long period before they need
to be reinflated. Thus, such products should have excellent gas barrier property [1]. Along with this most desirable property, the
cured composite should also have reasonably good mechanical
properties. For similar reason, fuel and air-con hoses should be
constructed with at least one layer exhibiting good to excellent
gas barrier property. In many existing hose products this property
is imparted by nylons [2], but there is a drawback in using the
same. The flexibility of the product decreases with the use of such
a material and it asks for an alternative material, to satisfy both gas
barrier property while maintaining the flexibility.
Butyl rubber (IIR) is the copolymer of isobutylene and a small
amount of isoprene. First commercialized in 1943, the primary
attributes of butyl rubber are excellent impermeability/air retention and good flex properties, resulting from low levels of unsaturation between long polyisobutylene segments. Tire inner tubes
were the first major use of butyl rubber, and this continues to be
a significant market today [3].
The development of halogenated butyl rubber (halobutyl) in the
1950s and 1960s greatly extended the usefulness of butyl by providing much higher curing rates and enabling co-vulcanization
with general purpose rubbers such as natural rubber and
styrene-butadiene rubber (SBR). These properties permitted