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unscientific
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Specifically, shining UV-light onto epoxy hardens it, but sometimes cracks/holes/voids form, why? I want to know the physics behind this!
That part is surprising to me - I didn't realize that that could be a significant factor in anything but gases.chemisttree said:Cure shrinkage itself is due to the crosslinked polymer having a smaller molar volume than the uncured resin, as Danger has indicated.
The hardening process of adhesives involves the evaporation of solvents or water, causing the adhesive to shrink. This shrinkage creates internal stresses within the adhesive, leading to the formation of cracks.
Yes, certain adhesives that have a lower shrinkage rate or those that cure at a slower pace can reduce the likelihood of crack formation during hardening.
Yes, factors such as high temperature, humidity, or uneven application of the adhesive can increase the chances of cracks forming during hardening.
Cracks in hardened adhesive can significantly weaken the bond strength since they act as stress concentrators and reduce the contact area between the two surfaces being bonded.
To repair cracks, it is best to remove the hardened adhesive and reapply a fresh layer. To prevent cracks, one can use adhesives with lower shrinkage rates, control external factors, and ensure proper adhesive application techniques.