PSI - Issue 2_B

A. Ueno et al. / Procedia Structural Integrity 2 (2016) 2323–2329 Author name / Structural Integrity Procedia 00 (2016) 000–000

2326

4

Relationships between viscosity and mechanical properties are indicated in Fig. 7. In this figure, three types of mechanical properties, tensile strength, elongation and apparent elastic modulus were compared, and scatter range and correlation coefficient are also shown in figure. It is obvious that the tensile strength is the most sensitive to a change in viscosity. Also it is found that scatter of tensile strength is very little. Therefore, it is considered that tensile strength is one of promising mechanical properties reflecting a chemical degradation.

600

● Elastic modulus E ● Elongation  ● Ten. Strength  B

0 Tensile strength (MPa) ， Elongation (%) , Apparent elastic modulus (MPa/mm) 100 200 300 400 500

R = 0.832 R = 0.887

R = 0.980

1.0 1.2 1.4 1.6 1.8 2.0 Viscosity, MPa ・ s

Fig. 7 Relationship between viscosity and mechanical properties.

3.2. Results of hardness tests Relationships between viscosity and nano-indentation measurements measured on cross-section of membrane are shown in Fig. 8. In this figure, three types measurements, DHT115-1, DHT115-2 and elastic modulus were compared. In this case, it is obvious that the DHT115-1 is a candidate to reflect the change in viscosity, because scatter of DHT115-1 is very little and also correlation coefficient is biggest. Therefore, it is considered that DHT115-1 is one of promising nano-indenter measurements reflecting a chemical degradation. Figure 9 shows relationships between viscosity and nano-indentation measurements measured on membrane surface. By comparing Fig. 8 and Fig.9, it is noted that data and its scatter measured on cross-section are always larger than that measured on membrane surface because of constraint by hard epoxy resin. Therefore, it is concluded that data measured on membrane surface are more valid than data measured on membrane cross-section.

200

100

● Hardness DHT115-2 ● Elastic modulus E ● Hardness DHT115-1

● Hardness DHT115-2 ● Elastic modulus E ● Hardness DHT115-1

80

150

20 Elastic modulus E /10 40 60

50 Elastic modulus E /100 100

R = - 0.269

R = - 0.474 R = - 0.388

R = - 0.622

R = - 0.706

R = - 0.662

0

0

1.0 1.2 1.4 1.6 1.8 2.0

1.0 1.2 1.4 1.6 1.8 2.0

Dynamic hardness DHT115-1, DHT115-2,

Dynamic hardness DHT115-1, DHT115-2,

Viscosity, MPa ・ s

Viscosity, MPa ・ s

Fig. 8 Relationship among DHT115-1, DHT115-2, E and viscosity. Fig. 9 Relationship among DHT115-1, DHT115-2, E and viscosity. (measured on cross section of membrane) (measured on surface of membrane)