Paper Number 8.2
Network
Evolution During Intensive Service
in Large OTR Tire Compounds –
Evidence for “Double Network” Formation.
Fred Ignatz-Hoover
Flexsys
America
L.P.
260 Springside Drive
Akron, Ohio 44333-2433
Voice:
330-668-8346
Fax:
330-668-8345
Email: Frederick.Ignatz-Hoover@flexsys.com
Ed Terrill
Akron Rubber Development
Laboratory
2887
Gilchrist Road
Akron, OH
44305
Large off-the-road
tires (OTR) experience reversion
both during cure and during service.
Intensive service exacerbates heat build up, creep and set
characteristics, especially in sulfur networks rich in polysulfidic
crosslinks. Recent experiments
demonstrate network evolution during intensive service. The networks subjected to intensive service
show analogous behavior analogous to the “Double network”. This suggests that as some bonds break due
to thermal-mechanical forces, new bonds form when the rubber is in a strained
state during the intensive service.
Antireversion
agents (ARA’s) work by either
slowing the rate of reversion or a mechanism of “crosslink compensation”. The slower rate of reversion and compensation
for broken crosslinks provide for significantly improved networks. During thermomechanically induced reversion,
newly formed bonds generated during intensive or severe service reduces heat
build-up, creep and permanent set characteristics. This work explores
compounding variations and the study of network evolution especially with ARA’s, which provides improved performance in large
tires under severe applications. Tires compound as such, have lower running
temperatures, less heat build-up, less, creep and less permanent set providing
better durability under severe conditions.