I am doing my PhD and currently doing epoxy composite with microcapsules. The size of the capsules are about 600micron. After mixing epoxy with curing agent (DETA), the microcapsules are mixed together with the epoxy liquid and let it cured. After it is cured, all the microcapsules seem settle down at the bottom of the epoxy specimen. How should I prevent it from settling down during the curing period?
Thanks.
In this situation the ultrasonic vibrator, probably, may be implemented.
Thixotropic filler, e.g. fumed silica, which at low loading (a few percent weight), at zero/low shear rate, should increase the apparent viscosity of the epoxy to help suspend the microcapsules uniformly, but allow casting and deaeration at higher shear rates.
Try to use a small quantity of surfactant (anionic - non ionic mixture) to stabilize the microespheres
You can increase your temperature while mixing your materials. After a period, your viscosity will be increased then, you can decrease the temperature and leave it to be cured completely at room temperature.
And what about another mechanical method to exclude gravitation factor and obtain uniform distribution of microcapsules in epoxide binder? This one is based on continuius or periodical rotation of container with material prepared.
Benjamin: Thanks for the reply. What kind of surfactant do you recommend? Any papers that relate to this issue?
Richard: Thanks for the reply. Dont think filler is a good option as it will change my composition of the matrix.
Mohammad: Thanks for the reply. Do you mean heat up the mixture for probably 2 hours and let it set first and then only cured at room temperature?
Serge: Thanks for following up. Whats that equipment or method call or do you have any paper for this method?
Dear Iee, I think, this equipment is very simple and may be easy constructed on the base of small electrical drive which produce a low frequency of rotation.
Experience suggests fume silica at less than 5% by wt loading has little effect on mechanical properties. I think work done by Shell Chemicals in the late 60's on their Epikotes demonstrated this.
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