Fail Of The Week: Beaker To Benchy More Bothersome Than Believed

Making nylon plastic from raw chemicals used to be a very common demo; depending where and when you grew up, you may well have done it in high school or even earlier. What’s not common is taking that nylon and doing something with it, like, say extruding it into filament to make a benchy. [Startup Chuck] shows us there might be a reason for that. (Video, embedded below.)

It starts out well enough: sebacoyl chloride and hexamethaline diamine mix up and do their polymerizing tango to make some nylon, just like we remember. (Some of us also got to play with mercury bare-handed; safety standards have changed and you’ll want to be very careful if you try this reaction at home). The string of nylon [Chuck] pulls from the beaker even looks a little bit like filament for a second, at least until it breaks and gets tossed into a blobby mess. We wonder if it would be possible to pull nylon directly into 1.75 mm filament with the proper technique, but quality control would be a big issue. Even if you could get a consistent diameter, there’d likely be too much solvent trapped inside to safely print.

Of course, melting the nylon with a blowtorch and trying to manually push the liquid through a die to create filament has its own quality control problems. That’s actually where this ends: no filament, and definitely no benchy. [Chuck] leaves the challenge open to anyone else who wants to take the crown. Perhaps one of you can show him how it’s done. We suspect it would be easiest to dry the homemade nylon and shred it into granules and only then extrude them, like was done with polypropylene in this mask-recycling project. Making filament from granules or pellets is something we’ve seen more than once over the years.

If you really want to make plastic from scratch, ordering monomers from Sigma-Aldrich might not cut it for ultimate bragging rights; other people are starting with pulling CO2 from the atmosphere.

Thanks to [Chaz] for the tip! Remember that the tips line isn’t just for your successes– anything interesting can find its home here.

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Dual-Wavelength SLA 3D Printing: Fast Continuous Printing With ROMP And FRP Resins

As widespread as 3D printing with stereolithography (SLA) is in the consumer market, these additive manufacturing (AM) machines are limited to a single UV light source and the polymerization of free-radical polymerization (FRP) resins. The effect is that the object is printed in layers, with each layer adhering not only to the previous layer, but also the transparent (FEP or similar) film at the bottom of the resin vat. The resulting peeling of the layer from the film both necessitates a pause in the printing process, but also puts significant stress on the part being printed. Over the years a few solutions have been developed, with Sandia National Laboratories’ SWOMP technology (PR version) being among the latest.

Unlike the more common FRP-based SLA resins, SWOMP (Selective Dual-Wavelength Olefin Metathesis 3D-Printing) uses ring-opening metathesis polymerization (ROMP), which itself has been commercialized since the 1970s, but was not previously used with photopolymerization in this fashion. For the monomer dicyclopentadiene (DCPD) was chosen, with HeatMet (HM) as the photo-active olefin metathesis catalyst. This enables the UV-sensitivity, with an added photobase generator (PBG) which can be used to selectively deactivate polymerization.

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