Even below its short-term strength, a bonded joint under sustained load slowly stretches. PSAs, hot melts, PVA and flexible adhesives creep most, especially as temperature rises toward Tg. Creep is tested by hanging a weight and measuring slip or time to failure. Designs carrying permanent loads use a fraction of the short-term strength or a more crosslinked adhesive.
Sign panels have slid half an inch down the wall, the tape is creeping in the afternoon sun.
Size a sustained-load PSA bond on static shear at the service temperature, not on peel or short-term strength.
Also heard as
- creep deformation
Related terms
Static shear
A tape test that hangs a weight from a bonded strip and records how long it holds before sliding off.
Cold flow
Slow flow of a soft adhesive at room temperature under its own weight or light pressure.
Tg
Glass transition temperature, above which a cured adhesive turns from hard and glassy to soft and rubbery.
PSA
Pressure-sensitive adhesive, the always-tacky layer on tapes and labels that bonds under finger pressure with no cure step.