4/20/99
I have following recipe to mix the four components for EPON 812.
For 25grs we use
11.556 g Epikot
7.125 g Dodecanylsuccinateanhydride,
6.275 g Methylnodicanhydride
and 0.375 g DMP-30 (2,4,6 Triphenol)
Well, anyone who uses other formulas to mix Epon or do you agree with my
formula?
I would be happy to receive other propositions to mix Epon or any
further information on this stuff.
It is the first time I try Epon while using the 3-component ARALDITE
normally.
Thank you for hints and tips,
keep trying ...
Michael Reiner
a2811111@smail.Uni-Koeln.DE
for Epon 812 with WPE 157 we use
52,3 g Epon
23,0 g MNA
23,0 DDSA
1,5g DMP30 or 2,5 g BDMA
best wishes
Anne Heller
Dr. Anne Heller
Arbeitsgruppe Elektronenmikroskopie
Institut fuer Botanik (210)
Universitaet Hohenheim
Garbenstr.30
D-70593 Stuttgart
Tel.0049-711-459-2180
Fax 0049-711-459-3355
http://www.uni-hohenheim.de/~heller/
We calculate for each bottle of Epon 812(or EMBed 812). Most
commercially available epoxy resins sold today give the "Weight for
Epoxy Equivalent" of the Epon component. The "WPE" is listed on
the bottle for each batch you buy. This value for Epon 812 usually
varies between 140-180.
If the same resin consistency is to be maintained, formulation of the
resin must change to compensate for the varying WPE's of the resin.
This can be done by varying the amount of hardener(anhydride) For
example, the weight of the anhydride used can be determined from the
following formula:
weight of anhydride= (weight of resin/WPE) x anhydride equivalent x
anhydride/epoxy ratio
WPE is determined from label on bottle.
anhydride equivalent = molecular weight of DDSA (Dodecenyl Succinic
Anhydride) = 226.0
NMA (Nadic Methyl Anhydride)=178
Ratio of anydride/epoxy = ratio of molar concentrations of anhydride to
epoxy
Luft's original 1961 mixture that gave optimal cutting qualities for
Epoxy 812 (also known as Epon or EMBed 812) was 0.7 A/E.
Example: If you wish to use 100 grams of Epon resin with a WPE of 160,
how much DDSA and NMA would you need to achieve an A/E of 0.7?
DDSA weight = (100/160) x 266 x 0.7 = 116.4 grams
NMA weight = (100/160) x 178 x 0.7 = 77.87 grams
You would combine 100 grams of Epon with 116.4 grams of DDSA and then
77.87 grams NMA with 100 grams of Epon. (note that you end up with 200
grams of Epon at the end) Mix these well and add DMP-30 at a 1-3%
ratio (we usually use 1%) And of course, we cut the amount to fit in a
30 ml syringe for storage and ease of use.
Good luck.
john
********************************************
John P. Shields
Center for Ultrastructural Research
151 Barrow Hall
University of Georgia
Athens, GA 30602-2403
(706)542-4080
jpshield@arches.uga.edu
Sorry, I forgot to add the Epon/araldite info.
If you are using an Epon/araldite formulation, go by the amounts listed
in the kit. If you lost this, you can contact any of the suppliers and
they are usually kind enough to mail that info.
I tend to stick with my "usual and customary" amount for this (as I am
a naturally lazy person):
Embed 812: 25 grams or 25 ml
Araldite 502: 16 grams or 15 ml
DDSA: 48 grams or 55 ml
DMP 30: 1.6 gram or 1.5-2 ml
I'm sure that there are others that have a more precise or different
rendering of this formula.
********************************************
John P. Shields
Center for Ultrastructural Research
151 Barrow Hall
University of Georgia
Athens, GA 30602-2403
(706)542-4080
jpshield@arches.uga.edu
When trying something new with embedding media, it might be best to go to
a formulation which has been existence for 30 years - the formulations by
Luft. These formulations have been used for millions of embedments with
success. Look in any TEM textbook and you will find them. The "medium
hard" formulation is a favorite of pathologists, because it is versatile
and will embed many samples satisfactorily.
By the way - It is not necessary to weigh out epoxides. Use disposable
syringes for measuring accurately. You will not be able to detect a
difference in block properties between monomers carefully weighed and
carefully measured. I have data to support this.
Hildy Crowley
<hcrowley@du.edu>