An Inexpensive Way To Break Down Plastic

March 27, 2025 by Bryan Cockfield 11 Comments

Plastic has been a revolutionary material over the past century, with an uncountable number of uses and an incredibly low price to boot. Unfortunately, this low cost has led to its use in many places where other materials might be better suited, and when this huge amount of material breaks down in the environment it can be incredibly persistent and harmful. This has led to many attempts to recycle it, and one of the more promising efforts recently came out of a lab at Northwestern University.

Plastics exist as polymers, long chains of monomers that have been joined together chemically. The holy grail of plastic recycling would be to convert the polymers back to monomers and then use them to re-make the plastics from scratch. This method uses a catalyst to break down polyethylene terephthalate (PET), one of the more common plastics. Once broken down, the PET is exposed to moist air which converts it into its constituent monomers which can then be used to make more PET for other uses.

Of course, the other thing that any “holy grail” of plastic recycling needs is to actually be cheaper and easier than making new plastic from crude oil, and since this method is still confined to the lab it remains to be seen if it will one day achieve this milestone as well. In the meantime, PET can also be recycled fairly easily by anyone who happens to have a 3D printer around.

Fighting The Scourge Of “Screwdriver Mange”

August 16, 2024 by Dan Maloney 45 Comments

We’ve all got our favorite hand tools, and while the selection criteria are usually pretty subjective, it usually boils down to a combination of looks and feel. In our opinion, the king of both these categories when it comes to screwdrivers is those clear, hard acetate plastic handles, which are a joy to use — at least until the plastic starts to degrade and exude a characteristically funky aroma.

But perhaps we can change that if these experiments on screwdriver “mange” hold up. That’s [357magdad]’s unappealing but accurate description of the chemical changes that eventually occur in the strong, hard, crystal-clear handles of your favorite screwdrivers. The polymer used for these handles is cellulose acetate butyrate, or CAB, which is mostly the same cellulose acetate that replaced the more explode-y cellulose nitrate in things like pool balls and movie film, except with some of the acetate groups replaced with a little butyric acid. The polymer is fine at first, but add a little UV light and over time the outer layer of CAB decomposes into a white flaky cellulose residue while the butyric acid volatilizes, creating the characteristic odor of vomitus. Lovely.

In the video below, [357magdad] takes a look at different concoctions that all allegedly cure the mange. TL, DW; it was a dunk in household ammonia that performed the best, well ahead of other common agents like vinegar and bleach. The ammonia — or more precisely, ammonium hydroxide — works very quickly on the cellulose residue, dissolving it readily and leaving the handle mange-free and looking nearly new after some light scrubbing. None of the other agents came close, although acetone did manage to clear up the mange a bit, at the cost of softening the underlying CAB in a process that’s probably similar to acetone smoothing ABS prints.

As for the funky smell, well, the results were less encouraging. Nothing really got rid of the pukey smell, even a roll in baking soda. We suspect there won’t be much for that, since humans can detect it down to 10 parts per million. Consider it the price to pay for a nice-looking screwdriver that feels so good in your hand. Continue reading “Fighting The Scourge Of “Screwdriver Mange”” →

Liquid (Reversibly) Solidifies At Room Temperature, Gets Used For 3D Prints

August 9, 2024 by Donald Papp 8 Comments

Researchers demonstrate sustainable 3D printing by using poly(N-isopropylacrylamide) solutions (PNIPAM), which speedily and reliably turn solid by undergoing a rapid phase change when in a salt solution.

This property has been used to 3D print objects by using a syringe tip as if it were a nozzle in a filament-based printer. As long as the liquid is being printed into contact with a salt solution, the result is a polymer that solidifies upon leaving the syringe.

What’s also interesting is that the process by which the PNIPAM-based solutions solidify is entirely reversible. Researchers demonstrate printing, breaking down, then re-printing, which is an awfully neat trick. Finally, by mixing different additives in with PNIPAM, one can obtain different properties in the final product. For example, researchers demonstrate making conductive prints by adding carbon nanotubes.

While we’ve seen the concept of printing with liquids by extruding them into a gel bath or similar approach, we haven’t seen a process that prides itself on being so reversible before. The research paper with all the details is available here, so check it out for all the details.

Hackaday Links: March 24, 2024

March 24, 2024 by Dan Maloney 6 Comments

Way to rub it in, guys. As it turns out, due to family and work obligations we won’t be able to see the next Great American Eclipse, at least not from anywhere near the path of totality, when it sweeps from Mexico into Canada on April 8. And that’s too bad, because compared to the eclipse back in 2017, “Eclipse 2: Solar Boogaloo” is occurring during a much more active phase in the solar cycle, with the potential for some pretty exciting viewing. The sun regularly belches out gigatons of plasma during coronal mass ejections (CMEs), most of which we can’t see with the naked eye because not only is staring at the sun not a great idea, but most of that activity occurs across the disk of the sun, obscuring the view in the background light. But during the eclipse, we — oops, you — might just get lucky enough to have a solar prominence erupt along the limb of the sun that will be visible during totality. The sun has been quite active lately, as reflected by the relatively high sunspot number, so even though it’s an outside chance, it’s certainly more likely than it was in 2017. Good luck out there. Continue reading “Hackaday Links: March 24, 2024” →

Conducting Plastic Can Replace Metal

November 6, 2022 by Al Williams 45 Comments

The University of Chicago has announced they have created a material that behaves like plastic but conducts like metal. They also say they don’t fully understand why it works yet. Usually, good conductors like metals have very orderly atomic structures, something that plastics tend not to have.

The material is based on nickel, carbon, and sulfur. The resulting material was conductive and stable. However, the atomic structure isn’t orderly like a traditional conductor.

Continue reading “Conducting Plastic Can Replace Metal” →

Big Chemistry: Synthetic Oil

May 2, 2022 by Dan Maloney 49 Comments

For as long as I’ve been driving, I’ve been changing oil. Longer than that, actually — before I even got my license, I did a lot of the maintenance and repair work on the family car. It seemed natural to do it back then, and it continues today, despite the fact that it would probably be cheaper overall to farm the job out. I keep doing it mainly because I like keeping in touch with what’s going on with my cars.

Oil changes require supplies, but the last few times I made the trip to BigBoxMart I came back empty-handed. I don’t know whether it’s one of the seemingly endless supply chain problems or something else, but the aisle that usually has an abundance of oil was severely understocked. And what was there was mostly synthetic oil, which I’ve never tried before.

I’ve resisted the move to synthetic motor oil because it just seemed like a gimmick to relieve me of more of my hard-earned money than necessary. But now that it seems like I might have little choice but to use synthetic oil, I thought I’d do what normally do: look into the details of synthetic oils, and share what I’ve found with all of you.

Continue reading “Big Chemistry: Synthetic Oil” →

Two-Dimensional Polymer Is A New Ultra-Strong Material

March 23, 2022 by Lewin Day 26 Comments

Plastics, by and large, are well-understood materials. Not as strong as most metals, but often much lighter, these man-made polymers have found innumerable applications that have revolutionized the way we live. The properties of plastics have been improved in many ways over the years, with composite materials like fiberglass and carbon fiber proving to have strength and lightness far beyond the simple properties of basic polymers alone.

However, a group of engineers at MIT have been working on a revolutionary type of polymer that promises greater strength then ever before while remaining remarkably light weight. It’s all down to the material’s two-dimensional molecular structure, something once thought to be prohibitively difficult in the world of polymer science.

Continue reading “Two-Dimensional Polymer Is A New Ultra-Strong Material” →