VM100 Black Methacrylate Adhesive problem

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VM100 Black Methacrylate Adhesive problem

VM100 Black Methacrylate Adhesive problem

Author	Message
Steve Broad	Steve Broad posted 5 Years Ago HOT Topic Details
Group: Forum Members Posts: 408, Visits: 4.1K	Hi. I have had a bit of a disaster, that actually turned out to be a bit of a godsend. Anyway, My passenger door is fibreglass but I have cut out most of it leaving just the edges to which I plan to stick carbon fibre panels. Did the cutting and made the panels, so far so good. Sanded the carbon with 80 grit and cleaned with acetone and allowed to dry. Likewise the fibreglass. Spread on the VM100 and clamped the panels on, one at a time, and left overnight to cure. All looked Hunky Dory. Offered door up to the opening and discovered that is had twisted! Bugger, now how the hell do I get the carbon panels off? Turned out to be very easy as they just peeled off! Question is, what dId I do wrong? Photos show edge of panel, I simply scraped off the glue residue with a Stanley blade. The glue is very securely adhered to the fibreglass.
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Warren (Staff)	Warren (Staff) posted 5 Years Ago HOT Post Details
Group: Administrators Posts: 2.5K, Visits: 8.5K	Looks like for some reason it didn't grip the carbon. How was the carbon sheet made? I wonder if it was just the mechanism of peel? Structural adhesives are vulnerable to peel - you will see some "anti-peel" fixings on bonded structures (eg lotus elise tub). That and the fact the adhesive wasn't cured fully cured might have made it easier to peel. Warren Penalver Easy Composites / Carbon Mods - Technical Support Assistant
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Steve Broad	Steve Broad posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x Warren (Staff) - 5/13/2020 11:53:05 AM Looks like for some reason it didn't grip the carbon. How was the carbon sheet made? I wonder if it was just the mechanism of peel? Structural adhesives are vulnerable to peel - you will see some "anti-peel" fixings on bonded structures (eg lotus elise tub). That and the fact the adhesive wasn't cured fully cured might have made it easier to peel. Hi Warren It had been on for over 24 hours. I have since tried again after cleaning with thinners and then acetone and it seems to have worked this time. I guess that there was some sort of residue on the carbon that I didn't get off first time. Sheet made using prepreg on aluminium mould, release film and breather cloth at 120 deg C
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Hanaldo	Hanaldo posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	To me it doesn't look like the carbon was prepped enough. MMA adhesives are more forgiving as they self-etch, but they don't work miracles - and fully cured epoxy is still quite a low energy surface to bond with. This is probably why it bonded well with the fibreglass; an epoxy pre-preg fully cured at 120° will be just about as tough as epoxy can get to bond to, while I assume your fibreglass panel was not pre-preg? I always prep fully, regardless of whether I'm using MMA/urethane/epoxy/etc adhesive. Scuffing by hand isn't great for a 'structural' bond, best to use a 40/60 grit linishing belt or mini rotary disc, and prep the surface evenly so you don't have low spots between the fibres that aren't prepped. You should also clean with acetone first, then abrade the surface. Then just blow the dust off with compressed air and wipe clean with a DRY cloth. Reason being, if you clean after sanding you are likely to introduce contaminants through the acetone/cloth onto your 'virgin' surface. You want to be removing contaminants first, then sanding to expose fresh material, and then bonding to that clean sanded surface.
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Steve Broad	Steve Broad posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x Hanaldo - 5/14/2020 2:45:26 AM To me it doesn't look like the carbon was prepped enough. MMA adhesives are more forgiving as they self-etch, but they don't work miracles - and fully cured epoxy is still quite a low energy surface to bond with. This is probably why it bonded well with the fibreglass; an epoxy pre-preg fully cured at 120° will be just about as tough as epoxy can get to bond to, while I assume your fibreglass panel was not pre-preg? I always prep fully, regardless of whether I'm using MMA/urethane/epoxy/etc adhesive. Scuffing by hand isn't great for a 'structural' bond, best to use a 40/60 grit linishing belt or mini rotary disc, and prep the surface evenly so you don't have low spots between the fibres that aren't prepped. You should also clean with acetone first, then abrade the surface. Then just blow the dust off with compressed air and wipe clean with a DRY cloth. Reason being, if you clean after sanding you are likely to introduce contaminants through the acetone/cloth onto your 'virgin' surface. You want to be removing contaminants first, then sanding to expose fresh material, and then bonding to that clean sanded surface. Cheers Hanaldo. I was using acetone to remove sanding dust but I see your point. I have had to be careful as the panel is only two layers of 200gsm and I didn't want to sand through it! I tried again but this time used thinners as a first cleaning course then acetone to remove any residue. This seems to have worked, but I will follw your recommendatiosn when I tackle joining the two halves of the driver's door, which will be carbon to carbon with a carbon joining strip.
	Reply Like 3
Warren (Staff)	Warren (Staff) posted 5 Years Ago HOT Post Details
Group: Administrators Posts: 2.5K, Visits: 8.5K	As above, if it is working fine now then contamination or poor surface prep are likely to be the only realistic causes. Rougher the better with carbon bonding. Peel ply finish is generally a good finish to bond to so you can add peel ply into the part on all the bonding points. If the peel ply areas are large, it might suck up enough resin to leave a few pinholes. This can be avoided by using some XPREG XA120 150g Prepreg Adhesive Film in those peel ply'd areas to add a bit of extra resin. Warren Penalver Easy Composites / Carbon Mods - Technical Support Assistant
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Steve Broad	Steve Broad posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x Warren (Staff) - 5/14/2020 1:46:11 PM As above, if it is working fine now then contamination or poor surface prep are likely to be the only realistic causes. Rougher the better with carbon bonding. Peel ply finish is generally a good finish to bond to so you can add peel ply into the part on all the bonding points. If the peel ply areas are large, it might suck up enough resin to leave a few pinholes. This can be avoided by using some XPREG XA120 150g Prepreg Adhesive Film in those peel ply'd areas to add a bit of extra resin. Cheers Warren, pinholes aren't an issue as everything is painted to hide the carbon :-) Would you place the adhesive on the surface next to the peel ply? My carbon supplier/sponsor agrees with you that it must be a contaminate issue: If you lightly abrade the carbon surface to give a key it should bond fine with methacrylate. One way to do that would be with Scotchbrite type material which won’t damage a thin laminate. If you do that with soapy water to remove any grease or other residue then rinse with clean water and allow to thoroughly dry it should do the trick.
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