I Googled this and the explanations lack any kind of scientific data, but it's easy to see there is a thermo reaction with the cyanoacrylate glue and the soda. Where it really comes into its own is as a filler. I don't see anywhere the proof that using the soda makes the joint 'stronger'. Where everyone gets excited is when they actually build up the joint with the soda; some putting the soda on first and then dripping on the cyanoacrylate glue....or using the cyanoacrylate glue first and then putting on the powder.
Eventually, this led me to a UK link where they featured a very expensive looking plastic welder with plastic rods. Eastwood offers one of these and now so does Harbor Freight. The HF model only offers three rod types; ABS, PVC and PP. Manufacturers use about two dozen types of plastics. Some plastics react poorly to cyanoacrylate glues, as you can snap the joints even after a day of setting. That's why I usually defect to epoxy unless I know the plastic type and its reaction to cyanoacrylate glues. ABS plastics on the other hand react perfectly to black, plumbing glue. The joints are chemically bonded.
And all cyanoacrylate glues are not the same. Some will crystallize over the yrs and fail. I use Rhino cyanoacrylate glue. Loctite makes a 'plastic welder' glue that really works too. Comes with a felt type pen that you rub on both surfaces, let dry and then use the glue on one joint surface only. The glue however will not keep long in the tube once opened.
Kevin
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