Structural Adhesive

EC-3448

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Hot/Wet Strength – Aluminum to Aluminum Bonds

Hot/Wet Exposure: One inch wide overlap shear specimens were placed in a 100% R.H.

cabinet for 14 days at 180°F.

Overlap Shear Strength After Hot/Wet Exposure

Test

Unprimed

EC-3924B Primed

Temperature

Control

Exposed

Control

Exposed

180°F

4480 psi

1495 psi

4840 psi

2575 psi

Substrates: 2024T-3 alclad aluminum, 0.063 inches thick.

Surface Preparation: Optimize FPL etch.

Primer: 3M™ Scotch-Weld™ Structural Adhesive Primer EC-3924B.

Primer Application: One brush coat.

Primer Dry: 30 minutes minimum air dry, plus 60 minutes at 260°F.

Cure Cycle: 260°F for 60 minutes, 10 psi pressure, 10°F rise rate/minute.

Test: Tested immediately upon removal from R.H. cabinet at 180°F according to MMM-A-132.

Product Performance

(continued)

Glass Transition Temperature, Tg.

Procedure: Cured pieces of 3M™ Scotch-Weld™ Structural Adhesive EC-3448,

3.2 mm x 10 mm x 60 mm were conditioned for 147 days at 100% R.H. and 120°F.

After conditioning, the specimens were submitted for DMA determination of Tg.

Tg Before

Tg After

Cure

Conditioning

Conditioning

250°F for 90 minutes

250°F

190°F

290°F for 60 minutes

255°F

187°F

Pre bond Shop Out – Time Relative Humidity Exposure

5 Hours

24 Hours

Test

Control

@ 60% R.H.

@ 60% R.H.

Overlap Shear

@ 75°F

6200 psi

6110 psi

5970 psi

@ 180°F

5380 psi

4800 psi

4340 psi

@ 250°F

3640 psi

1600 psi

1140 psi

T-Peel @ 75°F

39 piw

41 piw

44 piw

Adherends: 2024T-3 alclad aluminum (.020" thick for T-Peel).

Surface Preparation: Optimized FPL etch.

Layup: Adhesive was spread on one adherend and exposed to 60% relative humidity at 79°F for time specified before

assembly.

Cure Cycle: 260°F for 60 minutes, 5 psi, 10°F rise rate/minute.

Test Speed: Overlap shear at 0.1"/minute; T-Peel at 3"/minute.

Test Procedure: According to MMM-A-132.