In short

I'm looking for an acid that can solve a polyester, fiberglass composite. However it cannot damage steel.

First of all i like to say that i'm not a chemist. I work in a plastic moulding company. Let me sketch a background. We make bars out of a polyester strengthened by fiberglas. To make this we have the two materials beeing pulled through a heated steel pipe (the mould). The polyester melts around the fiberglass and forms a strong lightweight pole. However sometimes the pole breaks mid process and then there is a part that's stuck in the mould. Like in the picture

Part stuck in mould

It's very hard to remove the polyester/fiberglass bar from the mould, dare I say near impossible.

I was wondering if there is an acid that solves the polyester but makes no damage at all to the chrome steel mould.


closed as too broad by Mithoron, Todd Minehardt, Soumik Das, airhuff, Jan Mar 26 at 6:21

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  • $\begingroup$ Look using the terms " solvent for. ..". It seems a hard task because you have a rod trapped in the mould. If the mould cannot be open it might takes years. .. $\endgroup$ – Alchimista Mar 13 at 14:53
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    $\begingroup$ Is it not possible to heat the mold above the melting point of the polyester, then PUSH out the stuck bar with a rod? $\endgroup$ – jeffB Mar 13 at 15:11
  • $\begingroup$ we tried drilling, melting, ... if there is an acid or solvent of polymer that doesn't damage the steel, i would make a system that circulates, the acid, maybe even heats it to speed up the process. If it works after weeks, i'll be happy with it, a year, or years might be a bit too long $\endgroup$ – RubenDefour Mar 13 at 15:24
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    $\begingroup$ @jeffB we tried pushing it hydraulically with a force of 800kg, hammering, and the rod is usually just too long, and has too much friction, we're talking about a mould of a length of 1m50, $\endgroup$ – RubenDefour Mar 13 at 15:26
  • $\begingroup$ Can't you pretreat the mould by coating it, say with PTFE? Or would this not help? $\endgroup$ – Buck Thorn Mar 13 at 15:46

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