By Hanaldo - 6/22/2015 6:49:03 AM
Hi all,
I have come across an interesting problem that I've never seen before, was hoping someone might be able to give me some insight. I made a false floor for a Ford F1000 using one layer of 200g carbon on the surface, and one layer of 850g biaxial fibreglass. The part was infused with epoxy, as I always do and have done hundreds of times before. 0 micron drop over 24 hours registered on my digital vac gauge prior to infusion, so absolutely leak free. Infusion went perfectly, everything wet out nicely etc. Left to cure for 48-50 hours prior to demoulding. This is when the issue became apparent. I removed all the consumables as I normally do, then used compressed air to blow the part off the mould. As I blew the air into the gap between the part and the mould, this happened:  First thought was "s***, must have left the clear packing tape in there!" (the supplier I get the fibreglass from annoyingly insists on placing clear packing tape on the cut line when the cut some off the roll). Anyway, kept going with removing the part from the mould (I use Frekote, so it's not like much effort was required, it virtually fell out), and it just kept happening:   So I grabbed the offcut from the hole I cut in the centre, and the fibreglass peeled off the carbon easier than peel ply!  The 2 skins individually are very strong, the unidirectional fibreglass doesn't delaminate from the +45 degree layer when placed under load:  And the carbon is also strong, for 1 layer of carbon. So individually, the skins are performing very well and the resin is doing its job, it isn't delaminating from each skin. But there is just no interlaminar bond strength, I'm not exaggerating when I say it's harder to remove peel ply. These are materials and process that I have used many times, I'm not unfamiliar with any of it. But this is the first time I have seen this, and it's got me stumped. Anyone have any ideas?
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By Dravis - 7/13/2015 10:46:56 PM
Also, be very carefull with "unknown" peel-ply ... I was given a few sq- metres of peel-ply, it turned out to be treated with some sort of release agent.. came off the part much easier than regular peel-ply, but new layers would not bond properly to the parts ... had to sand them down, almost into the fibres ... 
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