Another vinylester vs epoxy thread.

Discussion in 'Materials' started by Steve W, Apr 5, 2025.

  1. Steve W
    Joined: Jul 2004
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    Location: Duluth, Minnesota

    Steve W Senior Member

    I have been using epoxy and polyester resins for more than 50 years, vinylester for probably 20 years.
    Like most people i have generally assumed epoxy to be stronger than polyester with vinylester somewhere in between. I don't think i have used polyester since i discovered vinylester so i tend to pick a resin based on the project at hand, always epoxy when working with wood or secondary bonding composites but whenever building composite parts my go to is usually VE (unless smell is an issue) Recently i was on a forum with a discussion on epoxy vs vinylester. Unfortunately i have not been able to find my way back to that thread but the gist is that when i pointed out that vinylester was not a poor second choice to epoxy for the OP as the VE that i use has much higher physical properties than the common boatbuilding epoxies we use, people were saying that epoxies are stronger when post cured and that epoxies keep getting stronger. If i could remember where that thread was i would like to ask where i can find out about epoxies getting stronger over time, this is not something i had heard before but i heard someone else claim this in a you tube video again last week. I know that when using epoxies you can unclamp and work with it the next day but it does continue to cure for another week before it reaches it full cure. But i have not seen any claims from manufacturers that it continues to get stronger beyond that. Regarding post curing it seems that if you follow the manufacturers post curing schedule you should get an increase of 10 - 20% in physical properties. So if i were to post cure a laminate done with, for example, West 105/205 epoxy (which is the strongest combination) i would still fall well short of the tensile strength of the CORVE 8101 vinylester resin i use. This is an infusion resin but the VE we use for hand layup has similar properties. Of course most of us are not post curing except for specific highly loaded items. Anyone know if post curing VE yields similar results?
     
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