International Journal of Adhesion & Adhesives 21 (2001) 481–485
A method for continuous monitoring of bond formation
between rubber and reinforced wire
*, Robert M. Shemenski
Amercord Inc., P. O. Box 458, Lumber City, GA 31549, USA
RMS Consulting, 204 Sutton Avenue, NE, North Canton, OH 44720-2615, USA
Accepted 10 May 2001
The integrity of a high performance, steel-belted tire is heavily dependent on the adhesion of steel reinforcement to rubber. A
bronze coating, having a nominal composition of 98.5% Cu (the balance being Sn), is plated on tire bead wire to promote adhesion
of the steel reinforcement to rubber.
Pull-out force is the current standard for evaluating adhesion as recommended by ASTM. This paper describes an in-situ,
continuous monitoring system designed to detect the rate of adhesive bond formation between rubber and steel reinforcement
during the vulcanization process. Parameters such as oxide chemical structure and thickness were investigated to assess the rate of
bond formation during vulcanization and their eﬀect on adhesion.
Results proved that this monitoring technique is an eﬃcient, reproducible, and reliable technique for studying the interfacial
interactions occurring between steel reinforcement and rubber during vulcanization. r 2001 Elsevier Science Ltd. All rights reserved.
Keywords: Bond; Oxide; Structure; Thickness; Continuous monitoring system
Charles Goodyear patented rubber vulcanization by
sulﬁdic cross-linking in 1844 . It was not until the 20th
century that the instruments for continuously monitor-
ing rubber rheology became available in the industry [2–
4]. Among these complex instruments, Monsanto
Rheometer has been used to determine the optimum
cure at various temperatures, as well as to determine the
physical properties such as tensile strength, modulus,
and elongation inﬂuenced by cure rate. Monsanto
Mooney has been used to determine the internal friction
of the molecular network of uncured rubber as it ﬂows
through a standard die or is sheared against a rotating
disc at a given pressure and time. Rheometric S has been
used to determine the viscoelasticity of rubber, which
has the ability of rubber to exhibit properties that are
characteristic of liquids (viscosity, plasticity) and of
solids (elasticity). Pure shear loading on a universal test
machine has been used to predict the general form of the
stress–strain relationship under a variety of moderate,
unaxial strain conditions. The area under a stress–strain
curve is a measure of entropy change, which is related to
the strain energy stored in the deformed network.
The above-mentioned instruments have been applied
to study the rheology of the rubber matrix. Other
sophisticated instruments for surface analysis, such as
electron spectroscopy for chemical analysis (ESCA) and
Auger electron spectroscopy (AES), have been applied
to understand the interfacial composition between steel
reinforcement and rubber after vulcanization [5–7].
However, an in-situ method for continuous detection
of bond formation between steel reinforcement and
rubber during vulcanization has not been available.
In a pneumatic tire, the steel reinforcement can be
bronze-coated for the bead area or brass-coated for the
cord structure. Purpose of these coatings is to promote
adhesion of steel wire to rubber. When these coatings
are exposed to the environment, they acquire oxide
coatings, whose thickness and structure can vary. These
characteristics of oxide coatings have a signiﬁcant
impact on the adhesion of steel reinforcement to rubber.
Traditionally, it has been assumed that adhesion of
steel reinforcement to rubber is established by the
*Corresponding author. Fax: +1-303-494-7787.
E-mail addresses: firstname.lastname@example.org (Y.-Y. Su), bob
mindspring.com (R.M. Shemenski).
0143-7496/01/$ - see front matter r 2001 Elsevier Science Ltd. All rights reserved.
PII: S 0143-7496(01)00026-4