Jim Marske comments...
From: Jim Marske
Sent: 10 January 2012 15:19
To: 'Philip Lardner'
Subject: RE: Epoxy query
The strength of the resin only is at best in the neighborhood of 9,500 – 10,000 psi so your infusion resin looks good. The 181 glass fabric and 55% glass has always been the test material standard that goes back to the mid 1950’s. The 181 is a tight weave fabric that is difficult to wet out but it is strong stuff. Down side is that it easily tears if damaged. You say the resin is a hi temp system? Be sure to post cure it above its Tg temp for about an hour otherwise the part may distort on a hot day.
Jim M
From: Philip Lardner
Sent: Tuesday, January 10, 2012 6:41 AM
To: 'Jim Marske'
Subject: Epoxy query
Hi Jim,
I had planned to use PTM&W's Aeropoxy for my build but it is proving to be prohibitively expensive to import it to Ireland - the shipping company and excise officials are charging me a fortune for handling this 'Haz-Mat' substance, so I am having to look for a suitable alternative closer to home.
The supplier I'm using for all my other composite materials also supplies an infusion resin (I'd prefer to use the resin infusion method anyway - more time to set things up / less exposure to nasty chemicles) which seems to fit the bill, including a high Tg temp. My only concern is that the stated tensile strength of the resin appears to be considerably lower than that of Aeropoxy.
Aeropoxy has a derived tensile strength of 45,870psi - page 32 of the data sheet has a footnote: "(1) These properties were derived with a 10-ply laminate, hand lay-up, style 181 Fiberglass Fabric, 55% glass content."
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www.ptm-w.com/dynamicdata/data/docs/PTM_...neCatalog30Jun06.pdf (page 32)
The infusion resin I am looking at has a stated tensile strength of 65.5 - 73.5MN/m^2, which my conversion utility equates to 9,499.97psi - 10,660.27psi. The supplier suggests that the magnitude of the difference in strengths is probably due to the method used to test the two resins - one derived from a standard resin/reinforcement lay-up and the other from the resin alone.
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www.easycomposites.co.uk/downloads/TDS/E...2-Infusion-Resin.pdf.
My question is - given that it is the carbon fiber reinforcement that gives the calculated strength to the part, is the tensile strength of the resin alone of significant importance in our application?
Any advice would be appreciated.
Happy New Year,
Phil.
