A statistically designed Analysis of Variance (ANOVA) model
was built in order to obtain a general understanding of the impact
of changing various parameters and their inter-relationships on
the static adhesion between NR and brass-coated steel cords. The
dependent variable is the pull-out force and the three indepen-dent variables including the promoter type, promoter concentra-tion and cord type. This ANOVA model is called ‘‘three-way
ANOVA’’. The model was built up using the mix formulations in
Table 2as a center point and varying the promoter type levels
(manobond and KMR), promoter concentration levels (0, 0.5, 1.0,
1.5 and 2.0 phr) and the cord type levels (cord 1 and cord 2).
Results of the ANOVA model are presented inTable 3. The values
of theF-statistic indicate that each of the three factors has a
significant effect on the pull-out force of the system. The cord
type factor has the highest effect on the adhesion force, followed
by the promoter concentration factor. The promoter type factor
contribution is the least. Studying the average values of the pull-out force of the three factors at different levels illustrates that the