I am doing research on Polymer Nano composites. I have a query about the fabrication technique I am going to use for my composite. I am using inorganic nano meter sized fillers as reinforcements while HDPE being in the form of pellets. I want to obtain maximum possible dispersion and while fabrication via twin screw extruder. Is it suitable to directly add nano sized fillers into twin screw extruder without doing any other premixing technique before adding simultaneously into Twin screw extruder?
(part 1)
I don't knowwhat "nano"materials you want to disperse in HDPE. First of all, usually you would need some dispersion aids, additives, surfactants. I can not tell you which ones, no idea what you intend to disperse.
Moreover, I don't know how really "nano" sized your additives are. Many people say "nano", but in fact it is micromiter size. Anyway.
(part 2=
(part 2)
In case of truely nanosized material, you will not be able to disperse it to smaller than at best 100 nm. Even already medium molecular weight HDPE won't allow that, that is because polymers will form a monomolecular layer around the dispersed particles, and the adsorbtion angle can not be infinitely small, the bending angle of the adsorbed layer can not be infinitely small.
please see here a basic description of how nanomaterials - here: carbon black - in a polymer matrix will be dispersed and structured:
Article Electrical conductivity in heterogeneous polymer systems. V ...
(part 3)
(part 3)
The smaller the particles are you want to disperse in HDPE, the more important it will be to
a) decide at which concentration you want to use your additives (the smaller, the less you need!)
b) consider to first prepare at least a premix, even better so a pre-concentrate ("masterbatch") which you can not well do in a twin-screw extruder.
In fact, to my experience, these twin-screw extruders' dispersion capabilities are poor.
(part 4)
(part 4)
If micron size, you can disperse your materials using a twin-screw extruder.
If truely nano-sized, you should use a banbury-type kneader first (there are also lab-size machines like this), prepare a higher concentration close to the maximum filling degree, then use twin-screw extruder to let it down to the concentration level you want to use.
(end)
Thank you Sir for such a detailed answer. Referring to the reinforcements, the nano fillers are of two different types. one of which is calcium carbonate and the other one is nano clay to be added simultaneously into polymer nano composites.
hhhmmm, I am not sure calcium carbonate is really nano-sized, same about nano clay. What are the particle sizes?
and in my experience, calcium carbonate and clay both can be easily distributed / dispersed in HDPE in a twin screw extruder, unless they are TRUELY nano (I have never seen really nanosized such fillers, but maybe new)
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