Talk Composites - The Forum for Advanced Composites

Vinyl/poly resin mold shrinkage and deformation

http://www.talkcomposites.com/Topic9327.aspx

By 20_rc51_00 - 1/21/2014 5:10:57 PM

I realize that there is a greater amount of shrinkage with these to resin types over epoxy.  Is the shrinkage or warpage apparent in a free standing form during cure or would it also become apparent with making a mold over a plug? I would think that if laying over a plug and allowing the curing process to take place with the plug intact this would be minimal or irrelevant. Any thougts?

My second question is if using such a mold with the reinforcement in the mold and infusing and curing at elevated temps/post cure will the mold be subject to relaxation of internal strain  etc? This could effectively destroy the tolerances of a part.

I have been using epoxy for molds simply because I'm not totally sure I understand the limitations of poly/vinyl.  poly/vinyl have a better $, decent Tg's typically so I would like to use them more in cases where they would be suitable.
By matthieutje65 - 1/21/2014 10:38:21 PM

I always use a vinylester gelcoat back with fiberglass... let your parts cure and postcure while on the plug and you shouldn't have much deformation on your moulds while using them at higher temp...
but all polyesterresins and vinyl esters are different so do some testing before Wink