Viscoelasticity Measurement of Encapsulation Resin (EVA) for Solar Batteries



Ethylene vinyl acetate copolymer (EVA) is a resin that is used most as an encapsulation material for solar batteries.
The viscoelasticity EVA before and after crosslinking was measured, and the difference in viscoelasticity due to crosslinking was compared.

Example of analysis

Comparing elastic modulus before and after EVA crosslinking by viscoelasticity measurement
Sample: Ethylene vinyl acetate copolymer (EVA)

■Measurement conditions

Equipment :Dynamic viscoelasticity measurement equipment DVA225 (available from IT Measurement & Control Co., Ltd.)
Measurement mode :Tension mode
Frequency :1Hz
Atmosphere :Air
Humidity range :10% - 90%RH (Measurement even in water is possible.

Fig. 1 Temperature dependency of sample before and after crosslinking

In temperature dependency measurement (Fig. 1), it was observed that the before-crosslinking sample melted from around 70℃, whereas the after-crosslinking sample showed a rubber-like flat region and high elastic modulus up to high temperature.

The use of this equipment makes it possible to investigate the temperature dependency of elastic modulus in a wide range through humidity control. The after-crosslinking sample was measured (as shown in Fig.2) while changing humidity, and as a result, it was confirmed that humidity had only little effect.

Fig. 2 Humidity dependency of the sample after cross linking

Search Number 6D002

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