Posted by Bengt Blomberg on May 11, 2001 at 14:03:46:
Hello Ed, what we remove is the uncured polyester enclosures in the laminate. Doing that does neither increase nor decrease the laminate strength. In fact there is an increase not worth to mention because some of the enclosures below the two top layers are cured instead of removed. In the top layers some of the cured polyester is also melted and blown away by the airstream. The main function for the Penetrator is to restore sufficient strength in those outer layers only in order to avoid relamination.
It is totally impossible to make a thin epoxy without solvents which can cure to sufficient hardness as a certain molecular weight = molecule chain length.
A cheap possibility to create some penetrating effects is to use a mxture of a portion of very low molecular weight resin with a portion of very high molecular resin but this resin becomes extremely dangerous by causing skin deceases to the operators after short time of handling. However there are some different possibilities to substantially reduce the surface tension in the high molecular phenol free type we are using without affecting the curing properties. We also need additives to make the resin stick to the raw glass fibres.
Regarding the strength, as described in the web site book, the hydrolysis even at an early stage causes the polyester to loose its bond to the glass = about 30% loss of structural strength. This strength is totally restored from the heating alone, a fact which have been confirmed by a number of University researchs.
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