Compact NMR for Tire and Rubber Testing
Rubber consists of long and flexible macromolecules, which are physically entangled. During processing,
raw rubber is mixed with fillers and processing agents, and usually sulfur following the formulation oft the
manufacturer. The raw product is vulcanized at elevated temperature and pressure where the sulfur forms
cross-links between the macromolecules. The resulting rubber network derives its physical properties
from the type of polymer, the polymer-filler interactions and the cross-link density. Rubber tubes, conveyor
belts and tires consist of several layers of rubber with different properties and often fiber and steel belts
to provide extra strength. The cross-link density correlates with the transverse NMR relaxation time T2,
which can be estimated with the NMR-MOUSE at different positions and depths in the intermediate and
final rubber products. Depth profiles through tires can also be measured with the NMR-MOUSE and
reveal the succession and properties of the different rubber layers. The type and quality of raw rubber can
be controlled with a Spinsolve spectrometer by 1H NMR spectroscopy of the raw product dissolved in a
solvent like chloroform.
shear
5.0
4.5
stress-strain
4.0
0.4
0.8 -4 1.2
1.6
n [10 mol cm-3]
rel. amplitude
T2eff [ms]
5.5
3.5
1.0 foamed NR
NR, sulfur
6.0
0.8
0.6
0.4
0.2
0.2
0.3
0.4 0.5
density [g / cm 3 ]
0.6
Figure 1: Correlation of NMR parameters measured with the NMR-MOUSE with physical properties of elastomers
[Adapted from J. Kolz et al., Investigation of the elastomer foam production with Single-Sided NMR, Kautschuk
Gummi Kunststoffe 60 (2007) 179 - 183]. Left: Correlation of the NMR relaxation time T2eff with cross-link density n
for sulfur cross-linked NR. T2eff is the NMR relaxation time measured with the multi-echo CPMG technique in the
magnetic stray fields of the senor. Right: Correlation of the signal amplitude with the gravimetric density of NR foam.
relaxation-weighted
H density [arb. u.]
Carbo
1
A B
0
5
10
15
nominal depth [mm]
amplitude [arb. u.]
1.0
20
A
0.5
B
0.0
0
2
4
6
8
time [ms]
10
12
Figure 2: Depth profiling with the NMR-MOUSE. Left: Photograph of the NMR-MOUSE PM25 measuring a depth
profile through a winter tire mounted on a steel rim. Right, top: Depth profile through the tire tread. The amplitude
is a relaxation weighted proton density corresponding to the grey scale in a magnetic resonance image. The depth
scale is distorted by the presence of the steel belt. The signal decays at positions A and B differ in their amplitudes
as well as in their decays corresponding to different T2eff.
NR Malaysia
NR Thailand
solvent
CHCl 3
TMS
solvent
CHCl 3
8
7 6 5 4 3 2 1
H chemical shift [ppm]
1
TMS
solvent
CHCl 3
0
10 9
8
7 6 5 4 3 2 1
H chemical shift [ppm]
1
TMS
x10
x10
x20
10 9
emulsion SBR Italy
emulsion SBR Poland
emulsion SBR United Kingdom
emulsion SBR Poland
solution SBR Japan
0
10 9
8
7 6 5 4 3 2 1
H chemical shift [ppm]
1
0
Figure 3: Spinsolve 1H NMR spectra of rubber dissolved in deuterated chloroform without (top) and with (bottom)
magnification. Left: NR from different plantations. Middle: Comparison of emulsion and solution SBR.
Right: Comparison of emulsion SBR from three different manufacturers.
CONTACT INFORMATION
For further information, please contact: [email protected]
GERMANYNEW ZEALAND
Philipsstraße 8
32 Salamanca Road
52068 Aachen, Germany
Wellington 6012, NZ
Tel: +49 (241) 70525-6000
Tel: +64 4 920 7671
Fax: +49 (241) 9278-6939
Fax: +64 4 471 4665
Or visit our website www.magritek.com
UNITED STATES
6440 Lusk Blvd., Suite 108
San Diego, CA 92121
Tel: (855) 667-6835
(855) NMR-MTEK