1

Database of Polymeric Materials for Hydrogen Gas Seals and

Dispensing Hoses

11 September 2018

Department of Mechanical Engineering, Faculty of Engineering, Kyushu University The Research Center for Hydrogen Industrial Use and Storage, Kyushu University

Shin Nishimura

Acknowledgement This research has been supported by the New Energy and Industrial Technology

Development Organization (NEDO) “Hydrogen utilization technology development (2013–2017)".

Chem ca sh ft (d n ppm)

if

Hydrogen Polymers in HYDROGENIUS

Rubbers materials and polymeric materials are "KEY MATERIALS" for hydrogen gas seal in equipment for hydrogen energy system.

Critical Pressure of Blister Fracture, PF, MPa

Hyd

roge

n Co

nten

t at 1

0 MPa

(ppm

)

No Blister

EPDM–CB25phr

EPDM–CB50phr

NBR–CB50phr

EPDM–SC60phr NBR–SC60phr

Blister

NBR–CB25部

EPDM–WC95 Unfilled EPDM Unfilled NBR

0 2 4 6 8 10 0

200

400

600

800

1000

1200

1400

8 7 6 5 4 3 2 1 0 i l i i

Unexpo

35H 23H

14H 1H

CrudeNBR

g) b)

f)

a)

e)

g)

d) h)

c) c)

c)

55H

Chemical Shift（ppm）

Two types of dissolved hydrogen CB filled EPDM

10MPa, 30℃，24hours●： Experimental Value −：Calculated Value

Elapsed Time（sec）

Hyd

roge

n Co

nten

t（mas

s.pp

m）

Development of Material Prototype Evaluation Product Evaluation Chemical Analyses Properties in Hydrogen Damage/Lifetime Analyses

Material Design Model Composites Fracture Modeling Design

Guideline

Model Composites

Hydrogen Content

Solid State NMR

O-rings

Hoses

Product

100℃

80℃ 30℃

Hyd

roge

n Pr

essu

re(M

Pa)

100

10 10 1 100 1000 10000

Cycle Number of Failure

Pressure Cycle Test of O-ring

Product Testing： Collaboration with Hydrogen Testing & Research Center EPDM(Hs70)：H2! 35MPa! 100℃! 15hrs.

EPDM(Hs70)：H2! 70MPa! 100℃! 3hrs.

Overflow Fracture

Buckling Fracture

EPDM(Hs70)：H2! 35MPa! 100℃! 15hrs. 1 mm

Blister Fracture

0.5mm

Magn y

10 mm

1 mm 1 mm 10 mm

Fracture Mechanics

Defect Origin

Matrix Origin

Time

Time

Grow of Blister

Grow of Blister

Molecular Chain Blister Crosslink

Defect

H d1 AOR

AG=H × LL d1:O-ring Diameter，H: Gland hight，L: Gland width Cross section area: AOR:O-ring ，Gland

O-ring squeeze ratio＝1ーH／d1・・・ 10〜20% Filling ratio＝AOR／AG・・・ 60〜80%

Establishment of Research Group

It is important to understand the relationship between structure of elastomeric compounds and their properties under high-pressure hydrogen.

We need diverse ideas from industries for the model compounds and hydrogen properties for measurement.

In 2012, we have established “The Research Group of Elastomers for Hydrogen Equipment” in The Society of Rubber Science and Technology, Japan.

In the research group, more than 40 members are active from the viewpoints of materials and elastomeric compounds design, hydrogen equipment design.

Polymeric Materials for Hydrogen Equipment

～90MPa pressure difference→ 70MPa Dispenser

Hydrogen Station ←Charging by

Hydrogen Accumulator

Compressor Fuel Cell VehicleGenerator

Rubbers and polymeric materials are used for gas seals and liners in the hydrogen equipment.

Piping System/Valves Breakaway Device

Plug/Receptacle Flexible Hose

Fracture of O-ring by Hydrogen

10mm

90MPa,100° C ×20 cycles

10mm

after 100MPa, 30°C ×25 cycles

Cross section

Fracture

Blister Fracture

Seal Break

Before test

5.5mm

140mm

NBR EPDM

Key Parameters for Fracture Modes of O-ring

EPDM(Hs70)：H2×35MPa×100℃×15hrs.

EPDM(Hs70)：H2×70MPa×100℃×3hrs.

Overflow Fracture

Buckling Fracture

EPDM(Hs70)：H2×35MPa×100℃×15hrs. 1 mm

Blister Fracture

0.5mm

Magnify

10 mm

1 mm 1 mm 10 mm

Material Strength and Hydrogen Solubility of Rubber Materials

Key Parameter:H2 content

Volume Increment of Rubber Materials originated from Swelling by Hydrogen

Gland Design in consideration for Volume Increment of the Rubber Materials

Key Parameter:Volume change

7 Design of Model Rubber Compounds

ITEMS NBR NF

NBR CB50

NBR CB25

NBR SC60

NBR SC30

EPDM NF

EPDM CB50

EPDM CB25

EPDM SC60

EPDM SC30

NBR(Nipol 1042) 100 100 100 100 100 - - - - -EPDM(Esprene

505) - - - - - 100 100 100 100 100

Stearic Acid 1 1 1 1 1 1 1 1 1 1 Zinc Oxide 5 5 5 5 5 5 5 5 5 5

Sulfur 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 MBTS 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 TMTD 0.7 0.7 0.7 0.7 0.7 0.5 0.5 0.5 0.5 0.5 ZnEDC 0.7 0.7 0.7 0.7 0.7 - - - - -

Carbonblack(N330) - 50 25 - - - 50 25 - -Silica(Nipsil VN3) - - - 60 30 - - - 60 30

Acrylonitoril Butadiene Rubber (NBR)

Ethylene Propylene Rubber (EPDM)

2,2’-Benzothiazyl Bis(dimethylthiocarbamoyl) Zinc Diethylthio-Disulfide (MBTS) Disulfide (TMTD) carbamate (ZnEDC)

Measurement of Hydrogen Content

Thermal Desorption Analysis (TDA)

Gas sampling (5-minute-interval)

Heater

GC (molecular sieve)

H2 gas

Carrier gas (Argon)

TCD

Tube furnace Hydrogen Vessel (30°C/~90MPa/24h)

H2

Hydrogen Exposure

Hydrogen content measurement (TDA)

Hydrogen Content Estimation

･After exposure to hydrogen gas, hydrogen content was measured by TDA.･A large volume of hydrogen release is considered before the measurement tests. ⇒Eq. (1) was fitted to remaining hydrogen content by using the least square method regarding equilibrium hydrogen content and diffusivity as unknown parameters, and the equilibrium hydrogen content was estimated by extrapolation.

Remaining

hyd

roge

n co

nten

t, C

H,R

(wt. ppm

) 200

150

100

50

0 0 5000 10000

Time after decompression , t (s)

Hydrogen release profile of hydrogen–exposed specimen of NBR-NF.

2 =13 mm =2 mm

□ Experimental data (NBR-NF)

Hydrogen exposure condition 10 MPa, 30 oC, 24 h.

Eq. 1

CH0

}]/exp[

{

})12(

]/)12(exp[ {32 )(

1 2

22

0 2

222

H0 2R,H

n n

n

n

tD

n Dt nCtC

　　　 　　　　　　　　　　

function Bessel order -zero the of root The : (m) specimen of Thickness :

(m) specimen of Radius : /s) (m tcoefficienDiffusion :

(wt.ppm) content hydrogen mEquilibriu:

(wt.ppm) at content hydrogen Remained :)(

n

2 H0

RH,

D

C ttC

(5 )

Solution of unsteady diffusion equation at hydrogen release

･･･ Eq. 1

(5) A. Demarez, A. G. Hock, F. A. Meunier, Acta Metallurgica, 2, 214 (1954).

10 Volume Measurement System KEYENCE 2D Silhouette Scanner TM-3000

The equipment is in the thermostat chamber.the temperature of the chamber is controlled at30°C, same as TDA measurement. The volume of 8 samples can be measured atsame time in every 5 minutes, same as TDA measurement.

230mm2 231mm2

229mm2

-----mm2

-----mm2

-----mm2

-----mm2

The surface area of the sample (13mmφ×2mmt) can be measured . The volume of the sample can be estimated by cube square root of the surface area. The results are consistent with Archmedean method.

11 Exposure Pressure Dependency of Hydrogen Content250 3000

▲ NBR-NF ● NBR-CB50 ○ NBR-CB25 ■ NBR-SC60 □ NBR-SC30

0 20 40 60 80 100 0 20 40 60 80 100

▲ NBR-NF ● NBR-CB50 ○ NBR-CB25 ■ NBR-SC60 □ NBR-SC30

Hyd

roge

n Con

tent

(wt pp

m)

2500

2000

1500

1000

200

Volum

e Cha

nge (%

)

150

100

50 500

0 0

Hydrogen Exposure Pressure Hydrogen Exposure Pressure (MPa) (MPa)

Hydrogen contents of model composites after hydrogen exposure are proportional to the hydrogen exposure pressure. Hydrogen contents of carbon black filled NBR are larger than those of unfilled and silica filled rubbers. Volume change of model composites after hydrogen exposure are proportional to the hydrogen exposure pressure. Filled rubbers shows smaller volume change.

12 Relationship between H2 content and volume

Volume Ch

ange V/V

0

2.2

2

1.8

1.6

1.4

1.2

1

Sulfur vulcanized NBR :unfilled :filled with silica 30phr :filled with carbon black :filled with carbon black

25phr 50phr

0 500 1000 1500 2000 2500

Carbon Black controls volume change of the compound Hydrogen Content (wt.ppm)

phr: weight parts per hundred weight parts of rubber

Model NBR Compound

Grade Acrylonitrile Content

Density (g/cm3)

Low Nitrile 18% 0.94

Mid Nitrile 29% 0.97

Mid-High Nitrile 33.5% 0.98

High Nitrile 40.5% 1.00

Very High Nitrile 50% 1.02

Compound:Sulfur vulcanization system Sulfur:1.5 phr, MBTS:1.5 phr, TMTD:0.7 phr, ZnEDC:0.7 phr Stearic acid: 1 phr, Zinc Oxide:5 phr

14 Hyd

roge

n co

nten

t (w

t.pp

m)

Unfilled NBR:Polymer Polarity

Hydrogen Content/NBR Volume Change/NBR 2500 2.2

AN50%

AN40.5%

AN33.5%

AN29%

AN18%

Max

imum

volum

e ratio

(V/

V 0 )

High Polarity

Low Polarity

High Polarity

Low Polarity 2.0 2000

1.8 1500

1.6

1000 1.4

500 1.2

0 1.0 0 20 40 60 80 100 0 20 40 60 80 100

Exposed pressure (MPa) Exposed pressure (MPa)

High polar NBR polymer suppress hydrogen penetration and volume inflation.

15 Unfilled NBR:Polymer Polarity

1.0

1.2

1.4

1.6

1.8

2.0

2.2

Max

imum

volum

e ratio

(V/

Vo)

AN50% AN40.5% AN33.5% AN29% AN18%

0 1000 2000 3000 Hydrogen content (wt.ppm)

Volume inflation per hydrogen content is constant for all NBR.

DBP Absorption (cm3/100g)

115 114 101 115 68 44

10μm 5μm

CB filled NBR:CB surface area

SAF ISAF HAF FEF SRF MT (N110) (N220) (N330) (N550) (N774) (N990)

Average Particle Size 19 22 28 43 66 280 (nm)

Nitrogen Surface Area 142 119 79 42 27 7-12 (m2/g)

HAF (N330)

CB filled NBR:CB surface area Hydrogen Content/NBR Volume Change/NBR 3500 2

○:unfilled unfilled 1.9 ◆:SAF50phr 3000

◆:ISAF50phr 1.8

2500

Volume Ch

ange

(V/

V0) ◆:HAF50phr

1.7 ◆:FEF50phr ◆:SRF50phr 1.6 ◆:MT50phr

1.5

1.4

1.3

CB filled 2000 unfilled

1500

1000 MT filled 1.2

500 CB filled 1.1

0 1 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100

Hydrogen Exposure Pressure(MPa) Hydrogen Exposure Pressure(MPa)

Hyd

roge

n Co

nten

t (w

t.pp

m)

Carbonblack filled NBR’s showed high hydrogen content and low volume inflation.

Volume Ch

ange

(V/

V0) 1.7

1.8

1.9

2

unfilled

CB filled NBR:CB surface area

Large surface area suppresses volume inflation by penetrated hydrogen.

NBR

1.4

1.5

1.6 MT50phr SRF50phr

SAF50phr ISAF50phr HAF50phr FEF50phr

1.3

1.2

1.1

1 0 500 1000 1500 2000 2500

Hydrogen Content (wt.ppm) 3000 3500

Issues on polymeric materials for tank and hose 19

Carbon fiber Reinforced Plastic (CFRP) High-pressure

Hydrogen Polymeric Liner

Permeation of H2 through polymeric materials

Deformation during pressurized-decompression cycles

Type IV tank

Hoses

Inner：Polyamide Reinforce：PBO Outer：Polyester

Flexibility and durability

nipple

Leak through interface between polymeric materials and metallic materials

20 Hydrogen Content of Polymeric Materials Oth

ers

Alip

hat

ic PA

PE

Fluor

ine

VOH

>7000

■：30MPa ■：50MPa ■：90MPa

Polyethylene

Category Type Molding χWAXS χDSC ρ

LDPE Low density NOVATEC LD ZE41K Heat Press 44.4 42 0.917

LLDPE Linear low density NOVATEC LL UR951 Heat Press 43.8 36 0.916

UHMWPE Ultra High Mw SKF ECOWARE 1000 Heat Press 62.1 49 0.924

MDPE Middle density JPE PE80 Heat Press 73.4 62 0.934

HDPE High density NOVATEC HD HB111R Heat Press 76.1 59 0.942

NOVATEC HD HB111R Heat Press 76.4 64 0.943

NOVATEC HD HB111R Blow 75.1 56 0.941

NOVATEC HD HB212R Heat Press 78.6 64 0.946

JPE PE100 Heat Press 80.0 65 0.947

Hi-ZEX 7000F Injection 78.7 67 0.947

WAXS(%)：Degree of Crystallinity determined by Wide Angle X-ray Scattering

DSC(%)：Degree of Crystallinity determined by Differential Scanning Calorimetry

(g/cm3)：Density determined by Archimedean method

PEの水素特性評価 Hyd

roge

n co

nten

t (w

t・pp

m) （x10-10）

3500 20

18 3000

4 500

Diffus

ion co

effic

ient

(m

2 /s)

2

0 0 MDPE/HDPE

16

14

12

2500

2000 10

8

6

1500

1000

0 20 40 60 80 100 0 20 40 60 80 100 Exposed pressure (MPa) Exposed pressure (MPa)

23 Summary

• Polymeric materials can be fractured by blisters and volume increment, which are originated from penetrated hydrogen．

• Volume change ratio is proportional to its hydrogen content. Carbon black can reduce the volume change of the compounds nevertheless their hydrogen contents are high.

• According to the results of model materials, O-rings for hydrogen equipment, such as breakaway device, are developed

• Liner materials of high-pressure hydrogen hoses and type IV tanks are required that low permeability of hydrogen, high durability for pressure cycles, good controllability of interface with metal materials.

• Database of elastomers for hydrogen equipment is now under discussion in the research group of the Society of Rubber Science and Technology, Japan.

24

Thank you very much for your kind attention.