Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Hi All,



A possible explanation for the acrylic crazing is a combination of using
H2O2 and heat.

Benzyl peroxide is used as a initiator for the setting reaction in dental
acrylic used in dentures.

Dentures are made using a lost wax casting processes where the denture is
waxed up and then invested in plaster. The mold is warmed up and the wax is
removed. A mixture on partly processed acrylic as a fine powder is mixed
with liquid monomer to form a dough usually with benzyl peroxide as the
initiator. A little heat is applied and the dough polymerises to form the
acrylic.

Patients are advised not use bleach on their dentures.



Cheers

Tim


Is it a problem with peroxide then?

'Cause I had a commercial acrylic bubble
tank that was used for years without problem.
Then after switching to CuCl (regenerated
with 40 weight H2O2) it crazed and went
brittle in about 6 months.





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