Which chemicals could be used to dissolve Polybutylene Terephthalate (PBT), but not dissolve brass?

Question

This is for a recycling project, I am looking to recover brass pins from electronic connectors made of glass reinforced Polybutylene Terephthalate (PBT).

The objective is to find a chemical which would be able to dissolve Polybutylene Terephthalate (or PBT, a common type of plastic) so that i can separate the brass pieces inside, without dissolving them too. I think that if it dissolves PBT the glass reinforcement will become dust so it won't be an issue.

So far my search has been unsuccessful, either it was acids which were too strong and would also dissolved] the brass, or common solvent which had no effect on the PBT (tested Acetone). Even 30% Caustic soda doesn't attack the PBT.

I found a method with high temperature methanol under pressure into a closed stainless steel shape, but it's way too complex for me to make. Similarly chemicals which are too cancerogenous are not worth it (at least given that i am not a specialist capable of handling the most dangerous ones).

If anyone has an answer or some ideas i'd love to hear it!

Thanks a lot!

Answer 1

PBT is a thermoplastic and its melting point is only 223 °C. Depending on its composition, brass doesn't melt until 900 °C or so. High enough heating may change the structural properties of the brass, but perhaps there is a temperature to which you can soften the plastic enough to detach the pins without damaging them.

Unfortunately, brass is easily attacked by many chemicals and PBT is resistant to many solvents, but something like hot DMSO or N-methyl-2-pyrrolidone may swell the polymer enough to separate the parts.