If epoxy is cured at low temperature to 50% degree cure, then further cured to 100% at higher temperature, how will that be different than curing to 100% at the higher temperature? Similarly, how will it be different from curing to 100% at low temperature for longer duration?
Additionally, after curing to 100%, will subsequent heating to higher temperature affect the epoxy?
Thanks for your input,
Zachary
Hi Zachary.
In my experience with epoxy resins coatings, each epoxy / hardener combination shows different behaviors. For a specific epoxy resin-hardener combination, a quick cure stage at elevated temperatures may not have good control of crosslinking reactions. In some experiences I have observed when I have cured in high heating of epoxy coatings it show cracks, while that in other combinations no cracks developed with the same curing stage.
Regards
Hi Zachary,
to reach 100% cure a minimum temperature is necessary, below that fully curing is not possible even at infinite times. Curing too quickly could result in position dependent shrinkage or cracks (sometimes different heating steps can reduce shrinkage effects) . Subsequent heating of fully cured resin result could in (beginning of) thermal degradation or reactions with humidity in air if temperature is too high or for too long times.
Regards
Dear all, also to consider where and how curing was performed, i.e., under compression (or open) in a mold. In this case, stress relaxations due to annealung may occur, and if highly cured, one may expect cracks, distorsion, and even rupture. Other thing that arises when curing is not achieved at once, is the uneven and gradient of crosslinks, mainly for thick items, this is essentielly due to the bad/low thermal conductivity of organic polymers. My Regards
I have this as a chapter in my book "Durability of Industrial Composites". Please send your email address to Antonio Carvalho
Hi,
According to my experience if you cure epoxy at normal temperature for long time in an open mold provide the release of stress relaxation and take longer time to hard segments to adjust to best crosslinking point in that case the epoxy will also show low glass transition temperature as compared to epoxy cured at high temperature because some of the segment will be condense in cross linked unit and remains non crosslinked state, If you cure epoxy at high temperature in an open mold that case some of epoxy surface will oxidize but the crosslinking take place abruptly. So my suggesting to control the moderate temperature condition to keep your epoxy system highly crosslinked with good crosslinking domains and with less degradation of some unit through oxidation. For this purpose you need to understand your epoxy medium and crosslinking agent with a series of crosslinking reaction if no data found in literature.
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