Degradation analysis in perfluorinated andhydrocarbon polymer electrolyte membranes
H2O2 exposure tests* simulating the membrane degradation caused by H2O2 generated on the electrodes inpolymer electrolyte fuel cells were conducted on perfluorinated and hydrocarbon electrolyte membranes tostudy the difference between the degradation behaviors of the two types of membranes.
* Honmura, et al., Polymer Preprints Japan, 54 (2), 2005

1. H2O2 exposure test method andtested electrolyte membranes

Polymer electrolyte
membranes

70ml/min
DRY
Chamber

WET
30ml/minSample

H2O2 aq.

CF2CFxy*

OCF2CFO

CF2

CF2 SO3H

CF3 mnOOONNNNOOOOOO

HO3S80ON
HN N20

SO3H** Saito, et al., Macromolecules, 2008

Exposure test conditions

Trap(KOHaq.)

Pure Water(for humidification)

CF2CF2- Hydrocarbon electrolyte membranes
SPI-8 (80)** (Thickness: 50 µm)
Polyimide electrolyte membrane

WET

N2*- Perfluorinated membranes
Nafion® 112 (thickness: 50 µm)
Nafion® 1035 (thickness: 90 µm)(Sulfon content: 112<1035)

Chamber temperature: 90 C, relative humidity 30%RH, test time 100 hr- Perfluorinated electrolyte membrane: H2O2 solution concentration 30%- Hydrocarbon electrolyte membrane: H2O2 solution concentration 3%

System specifications
Temperature: Room temperature - 100 C, Humidity: 20 - 90%RH,Sample size: 7 cm x 7 cm

2. Analysis results for the decomposition products and electrolyte membranes obtained in the H2O2 exposure test
Changes in the membrane molecular weight (GPC)

Ion chromatograph (IC-MS) for the decomposition
products(collected fluid)
6Nafion®
1：F-Nafion® 112F-:31mg/g

3202 6Nafion® 1035
F-:17mg/g

1255001010141515202025251 .51 .00 .50 .02101 .23030

時間（分）SPI-8 (80)12610HCOO- :52mg/g

8The peaks for 2 to
13 identified thecomponents
by IC-MS.

64

HOOCCH2COO-

10359ｍ /ｚ

2～52

7 8

11 .0MS spectra of peak #11(IC-MS)（Image）
CPS

Current
Conductivity (s)
電気伝導度（μS）

2：CH3COO9：CF3COO3：CH3CH(OH)COO-10：SO424：(OH)CH2COO- 11：CH2(COO)225：CH3CH2COO12：(COO)226：HCOO13：C6H4(COO)227：C6H5COO9

dW / d Log M

電気伝導度（μS）

Current Conductivity (s)142 .0

8：NO3-dW / d LogM

512 .51110
時間（分）Time(min)

Nafion® 112
blank(Mw:224000)

Nafion® 1035
after H2O2 exposure test
(Mw:93300)

Nafion® 1035
blank(Mw:164000)

103

10SPI-8 (80)410510610710810

6107108

M o le c u la r W e ig h t

blankafter H2O2 exposure test

0 .6

Mw：17700

0 .4

Mw：291000

13125Nafion® 112
after H2O2 exposure test
(Mw:121000)

0 .2
100 .02
10000 .8Nafion®

1520

 Major decomposition productsNafion® : Fluoride ion , SPI-8(80): Formic acid.
 The amount of F- produced per unit weight was larger withNafion® 112.



10310

4105

M o le c u la r W e ig h t

The weight average molecular weight (Mw) of Nafion® was decreased toabout 1/2 in Nafion, that of SPI-8 (80) was decreased to 1/10 after H2O2
exposure test, respectively.
There was no significant difference between the molecular weight
reduction rates in Nafion® 112 and Nafion® 1035.

-Perfluorinated electrolyte membranes have relatively high resistance to H2O2. Although production of H2O2 on hydrocarbon
electrolyte membranes with low gas permeability is presumed to be low in an actual cell, the presence of H2O2 will readily
degrade the membranes easily.

-Production of fluoride ion/formic acid, and reduction in the membrane molecular weight are also observed in the degradation
analysis using an actual cell, and the present study is considered to be an effective accelerated degradation test.
Part of the present study was commissioned by the New Energy and Industrial Technology Development Organization (NEDO).
2010年７月TRCポスターセッション2010 No.Ⅷ-2
P00743材料物性第１研究室20100712
STC：開(20100818)