Does anyone knows why there are formation of bubbles after vulcanization even though I already dried it completely at room temperature and in the oven (40°C)?
And how you remove or prevent the formation of bubbles after vulcanization?
Dear Nafeesa Mohd Kanafi, what is you vulcanizing system ? For example, benzoyl peroxide and AIBN both produce CO2 and N2 upon decomposition, respectively. My Regards
Dear Nafeesa Mohd Kanafi, your ask is very general. Can you share more info? Formulation ? Condition ( parameters and machinery) of vulacanization ? Wet carbon black, formation of gas within procesing within sample, press condition.... etc. Kind regards Jirka
Dear Abdelkader BOUAZIZ and Jiří Brejcha, my vulcanizing agent is sulphur, while the sample is the mixture of natural rubber latex and cellulose derivative.
I did the compounding by film casting. Before vulcanization, I dried the sample at room temperature for 3 days and in oven at 40°C overnight. Drying at room temperature took longer time because i need to prepare sample with thickness 2mm, at least.
I had read that, there are several technique to remove the bubbles like;
1) slower stirring speed during compounding
2) gentle centrifugation (1000-3000 rpm for 1-2 minutes)
3) vacuum degassing
I did no 1 and 2 techniques.
However, there are still some bubbles formed. I did my vulcanization at 140°C.
Dear Nafeesa Mohd Kanafi, thanks for the details, what is the casting solvent ? You should enhance RT drying by vacuum. Good Luck in your work
Dear Abdelkader BOUAZIZ , I dont need solvent since all the compounds are in liquid form. Thank you for your suggestion!
No thanks, generally better results are obtained with solvent casting, at least homogenization is much far better. If there is no side reactions, it is the entrapped air that causes bubbles. The following free access document gives some possible chemical reactions on cellulose. My Regards
DOI: 10.5772/61431
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