Patcharin Thamasirianunt. Improvement of bonding between natural rubber and nitrile rubber by chlorination of natural rubber surface . Master's Degree(Polymer Science and Technology). Mahidol University. : Mahidol University, 2007.
Improvement of bonding between natural rubber and nitrile rubber by chlorination of natural rubber surface
Abstract:
Natural rubber (NR) and nitrile butadiene rubber (NBR) exhibit different
mechanical properties. NR is known as a better dynamic and mechanical material than
nitrile rubber. NR contains some poor properties such as low oil and weathering
resistance. Encasing NR with nitrile rubbers is one way to combine the good
properties of these two kinds of rubbers. However, the adhesion between them is
naturally poor. It is probably improved by chemical surface treatment especially
chlorination of the NR surface.
In this research, a NR sheet was chlorinated in a mixture of sodium
hypochlorite and hydrochloric acid solution. The available free chlorine was 0.15%
mole approximately. The chlorination time was covered a range of 0-30 minutes. The
degree of chlorination determined by X-ray absorption spectroscopy (XAS) increased
with chlorination time up to 10 minutes and leveled off afterwards. The surface
properties of the chlorinated NR sheet investigated by Atomic Force Microscopy
(AFM) showed the surface stiffness and roughness increased steeply with treatment
time. Adhesion between chlorinated NR and NBR shows the maximum peel strength
at 1 min of chlorination time. That proved their adhesion depended not only on the
amount of chlorine substitution on the NR surface but that surface properties also
played an important role in the adhesion of NR//NBR. Other parameters such as the
effect of chlorination on uncured NR, carbon black loading in NR compound,
precuring of NR sheets before chlorination, filler type in NBR compound, as well as
the stability of bonding were also studied in this work.