Effect of fillers on Epoxy

General Composites Discussions Composites Talk
#1

Just wondering what the impact is of various fillers is on the impact toughness of a poured epoxy part.
fillers being :
Graphite powder
microballoons
cabosil
Milled glass fibers.
etc.

I’m just wondering if there’s something in my cabinet that I can add to the epoxy to make it more flexible, less brittle and enable it to absorb some more energy prior to failure.

I can make things and drop
things on them butwas wondering if anyone knew already.

The only papers I can find on the subject is graphite powder
http://www.ijetae.com/files/Volume3Issue2/IJETAE_0213_71.pdf

#2

Fillite and microballoons usually make epoxy more crash resistant (by adding a crash zone), but also a bit brittle. Fibrous materials Always are good. (why on earth does my Internet Explorer Always autocorrect Always with a capital???)

#3

I know about flow modifier like Cytec Modaflow, because mineral fillers always made more rigid and less flexible parts, graphite is a kind of exception because its a laminar structure, its well knowed as lubricant additive.
regards

#4

A chopped fibre of glass or carbon should make it less brittle although it becomes less pourable??

I often add chopped carbon to glue for important structural parts.

#5

What’s Internet Explorer?

#6

cabosil’s (thixotropic Silica) claim to fame is that you can thicken to your hearts content without it ever losing it’s stickyness, it’ll never turn to silly putty on you when you add a ton like other fillers. It really adds nothing to the strength of the epoxy though like you might want for filling some bigger gaps.

also it is an FDA approved food additive so feel free to add it to soup/gravy to thicken it up :wink:

#7

get some toughened epoxy like Pro-set adv176-276, or Spa bond 345- you will have to force it into the mold since it is much thicker and not pourable, the pro-set is thinner than the spa bond

#8

I just got some CTBN for the same reason. There are quite a few papers and tests done on adding it to epoxy for improving fracture toughness and % elongation.

http://scholar.google.com/scholar?q=ctbn+modified+epoxy&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ei=2lBPUuGKKYmQiAL4jYCACw&ved=0CCkQgQMwAA

(If the link doesn’t work, i just searched “ctbn modified epoxy” on google scholar)

But this also happens to be my job, so I’m not sure of its commercial availability.