Meaning
Molecular breakdown processes reduce the efficacy of light sensitive chemicals used to trigger polymerisation in UV curable resins and coatings. The occurrence of photoinitiator degradation often results from improper storage of raw materials or excessive heat during the curing stage. This loss of chemical activity prevents the resin from reaching its full mechanical strength.
Radical Exhaustion
Absorption of light eventually consumes all the available active molecules in the mixture. If the light intensity is too low, the radicals react with oxygen or each other instead of the monomer. This phenomenon results in a tacky surface finish that does not fully harden.
Byproduct Formation
Breakdown of the initiator creates small volatile molecules that can migrate out of the cured plastic. These fragments often have a strong chemical smell that is noticeable in printed packaging or moulded parts. Some of these substances are regulated and must be monitored during safety testing.
Cure Depth
Incomplete reaction through the thickness of the part happens when the surface absorbs most of the incoming radiation. This leads to a hard outer shell over a soft or liquid interior. Adjusting the concentration of the chemical can help achieve a more uniform cure throughout the material.
