Properties and Nano-observation of Natural Rubber with Nanomatrix Structure - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 330

Figure 15. 13 C CP/MAS NMR spectra for (a) DPNR- graft -PS-5.5 and (b) DPNR- graft -PS-5.5 sulfonated
with 0.8 N ClSO 3 H.

The water uptake of the sulfonated DPNR- graft -PS-5.5 at 75 mol% sulfur content
was 1/15 times as low as that of the sulfonated PS. It was comparable to the water
uptake of Nafion®117. ® 117. This may be explained to be due to an effect of the nanomatrix.
The nanomatrix structure was found to play an important role in not only the excellent
proton conductivity but also less water uptake, which were necessary for the proton
conductive polymer electrolyte.

table 2. T g , sulfur content, and electrochemical properties of sulfonated DPNR- graft -PS, sulfonated
PS and Nafion ® 117.
Sample name

Gel content
wt%

Sulfur
content wt%

IEC meq/g Conductivity

S/cm

Water
uptake wt%

T g °C

Sulfonated DPNR-
graft -PS 0.8 N

140.6 90.4 75 2.43 9.5 × 10 -2 24.3

Sulfonated PS - - - 1.50 3.2 × 10 -2 340.0

Nafion ® 117 169.2 90.6 - 1.02 8.0 × 10 -2 18.6

CoNClusioN
Natural rubber with the nanomatrix structure was found to possess the outstanding
viscoelastic properties and the excellent proton conductivities. Natural rubber with
the nanomatrix structure was prepared by graft-copolymerization of styrene onto