time ago. However, such study for blends of the rubber
and PH has not been addressed earlier.
Investigation of compositional parameters in rubber/
PH blends by one-factor-at-a-time method, i.e.,
varying only one parameter while keeping all others
constants, is very complicated task and requires performing
a large number of experiments. To reduce
the size of experiments, several experimental design
methods have been presented.18 Among them,
Taguchi’s method has found great successes in
designing and optimizing the engineering systems,
so that the literature indicates a number of studies
in this regard.19–23 This method has also been used
successfully to optimize the fillers composition of
the friction materials.24 Generally, the Taguchi
method can be utilized to obtain various information
about the system under investigation such as
average factor effect, relative influence of factors
(contribution of factor to a result), possible interaction
between factors (influence of levels of one factor
on the effect of another) and optimum condition.
These can be achieved by laying out the experiments
based on appropriate orthogonal array and
performing appropriate statistical calculations to the
results.25
This article deals with the mixtures of two different
synthetic rubbers consisting of SBR and NBR
with novolac type PH, which can be used as organic
binder of the composite friction materials particularly
for railroad brakes. Special attention is given to
acquire further understanding concerning the influence
of the constituents of the blend including the
rubber vulcanizing ingredients and the resin content.
To reduce the size of experiments, Taguchi’s experimental
design method is utilized to investigate the
compositional parameters of the blends. The morphological
characteristics of the blend are also examined
by using dynamic and static mechanical analysis
and scanning electron microscopy (SEM).