Here's a reply from the supplier of the IN2 Infusion Resin I was looking at - explaining a possible reason for the large disparity in tenisle strength figures compared to Aeropoxy. My email query to Easy Composites is below that. I'm still waiting for a reply from the manufacturers of Aeropoxy for their insight - I'll forward that when I get it.

Phil.

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Hi Philip,


It does seem odd! our resin is tested in the standard method; un-reinforced standardised token on a strain guage, I'm quite not sure what they mean by 'derived', I've had a scan over thier data and the interesting thing is the compresive strengths (where listed) are around 4-5 times less than that of the tensile, (circa 11,000psi) which is what you would expect from the data from a laminate, normally the compressive and tensile strengths are in the same ball-park for resin alone, which I am confident is why the data is so far different, you could expect the compressive strength to double and the tensile to increase by a factor of 5-10 with glass fibre reinforcement. also if you take a look at the adhesives and filler from the same range the tensile strength of those (derived from the same base resin) ranges between 3000 and 7000psi which is about where most epoxies sit, it's a bit missleading if you ask me!



On the data that I can see I would guess that thier resin alone would be in the range of 40-55 Mpas but I cannot say for sure, if their figures are for resin aIone I would like to be the one that tells NASA! If I can help with anything else the let me know.


Best Regards,

Paul Statham.

Carbon Mods/Easy Composites
Unit 39 Parkhall Business Village
Parkhall Road
Longton
Staffordshire
ST3 5XA

( +44 (0) 1782 324000 | fax. +44 (0) 1782 596868
: www.carbonmods.co.uk | This email address is being protected from spambots. You need JavaScript enabled to view it.

From: Philip Lardner [This email address is being protected from spambots. You need JavaScript enabled to view it.]
Sent: 05 January 2012 11:49
To: This email address is being protected from spambots. You need JavaScript enabled to view it.
Subject: Tensile strength of epoxies


Hello,


I am trying to compare the cured properties of your IN-2 Epoxy Infusion Resin against another resin system and am uncertain if I have correctly converted the Tensile Strength units. The figures for the two epoxies appear to be different by an order of magnitude, which makes me suspect that either I have made a mistake or that there is an error in the units specified.


Your IN2-Infusion-Resin has a stated tensile strength of 65.5 - 73.5MN/m^2, which my conversion utility equates to 9499.97psi - 10660.27psi - www.easycomposites.co.uk/downloads/TDS/E...2-Infusion-Resin.pdf.


The epoxy resin system I wish to compare it against is called Aeropoxy (which is not an infusion resin) - www.ptm-w.com/dynamicdata/data/docs/PTM_...neCatalog30Jun06.pdf (page 32) which gives a tensile strength of 45,870psi. A footnote to the table of properties on pg. 32 of the data sheet states "(1) These properties were derived with a 10-ply laminate, hand lay-up, style 181 Fiberglass Fabric, 55% glass content."


Your IN2-Infusion-Resin data sheet does not say how its tensile strength numbers are reached. Could this be the reason for the large difference in the stated tensile strengths or am I trying to compare apples with oranges?


As it is the reinforcement fabric/cloth (carbon fiber or fiberglass) that supplies the majority of a part's strength, is the tensile strength of the resin even significant?


Any help would be most appreciated.


Phil Lardner