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Science Technology

Chemists Sweeten Plastics For Faster Diodegradation 50

Posted by timothy from the sweet-toothed-revenge dept.
Makarand writes "Nature has an online article describing attempts of chemists to create tweaked versions polythene, polystyrene and polypropylene that would rapidly biodegrade in a landfill in the presence of soil bacteria. Their technique adds sugars to the polymer chains, like pendants on a necklace, sweetening them in the process and making them palatable to soil bacteria. Less than 3% of the final plastic would be sugar. However, soil bacteria open the chains when they feed on the sugar kicking off the decay process."
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Chemists Sweeten Plastics For Faster Diodegradation More

Chemists Sweeten Plastics For Faster Diodegradation

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  • Ok, so aparently plastics aren't sweet enough [slashdot.org] already? :) Adding more things to entice ants is going to keep the Orkin man busy.
    • If you don't want something for the short-term, don't manufacture it this way. Stuff like foundation seals, car parts, tools, etc, that doesn't get tossed out very often doesn't have to be made with this type of plastic. Stuff that is frequently disposed of (diapers, water filters, etc) can be made from this process, and won't cause nearly so much of a problem.
  • By weight, less than 3% of the final polymer is sugar, so the material is more or less the same. But bacteria such as Pseudomonas and Bacillus break open the chains when they chomp on these sugary snacks, kicking off decay.

    It doesn't tell us which kind of sugar; i.e. whether it is a mono- or disaccharide. Does anyone know if the mentioned bacteria eat specific kinds of sugar (Bacillus is a very common one I think) or that they eat all sorts (gluctose, galactose, lactose, fructose, etc.)?

    • From the article (emphasis added):
      Digambar Gokhale and colleagues at the National Chemical Laboratory in Pune mix the styrene subunits of polystyrene with small amounts of another substance that provides a chemical hook for sucrose or glucose pieces. They then add sugars to the styrene chains like pendants on a necklace.

      It does say what kind of sugar: sucrose or glucose.
      • You know, I'm going to admit this because it makes me stupider than if I didn't: I read the article and missed it. Skimming too fast I guess. If I didn't read the article, I'd come off as a jerk-off, but this really seals my stupidity.

  • A cheaper solution (Score:5, Insightful)

    by the_other_one ( 178565 ) on Wednesday December 04, 2002 @01:47AM (#4808121) Homepage

    Cut plastics out of packaging. Stop making disposeable products.

    Is this biodegradeable plastic research really another attempt at planned obsolesence?

    • Yeah, as usual they attempt to deal with the results of some trouble (plastic over-consumption) instead of thinking of ways to reduce plastic use in the first place...
      Just go to your local shop (food, music, whatever), buy a few products, and figure out for yourself how much of all that plastic you really need...
    • While you may have an answer, you didn't provide a method.

      I think the best solution is to legislate that all companies are responsible for their products throughout their entire life-cycle, from their creation to their recovery/recycling. This is already done in a much more ecologically savvy part of the world : Europe.

  • We would want this in only certain kinds of plastics. (e.g. drinking cups).

    There was an article not-long ago about an old iBook infested with ants, and someone said that plastics, after a long time, separate, and some of the "corn syrup solids" or whatever float to the top or something, making it like attractive to ants?
    Ah screw that....
    ...google-google-google....

    Actual comment [slashdot.org]. (Attached to story [slashdot.org])

    p.s. funny, I didn't even use google this time! Now that's branding -- using Kleenex not just for "facial tissue" but for anything used to wipe anything. I LOVE YOU GOOGLE!!!
    • Curses [slashdot.org] 3-State Bit you beat me to the punch. I read the article, and the first thing I thought of was "Great. Now not only do we have to worry about this in our electronics, but imagine the fun that will occur should this ever make its way into...oh, say, irrigation systems, sprinkler systems, etc..." And imagine how much fun this will be for people who's business is warehousing plastic products.
      Plastic is omnipresent in our society, and while it's not great for the environment, we don't necessarilly want one of natures most prolific creatures chewing on our essential infrastructure.

      • Re:Obviously... (Score:3, Insightful)

        by gotih ( 167327 )
        i hope you were kidding.

        we have different kinds of plastics for different applications. some are well suited for heat, others for flexibility. well, now we will have one that mcdonalds can use and claim to be helping the environment. don't worry your little american schitzo-from-the-doomsaying-tv brain, we won't have a rash of sprinkler systems degrading because the construction company bought 'biodegradable' plastic.

        i say use a mug [umich.edu]

  • word play (Score:4, Funny)

    by tswinzig ( 210999 ) on Wednesday December 04, 2002 @01:52AM (#4808146) Journal
    Diodegredation. When god is disgraced?

    Nah...

    Diodegration. When something decomposes due to the work of God?

    Nah...

    Biodegration. When something decomposes due to the work of biological agents.

    BINGO!

    • Re:word play (Score:5, Funny)

      by AJWM ( 19027 ) on Wednesday December 04, 2002 @01:17PM (#4811094) Homepage
      No, no, read the word again.

      It is as spelled: diodegradation -- the process of grading a collection of diodes, e.g. sorting them according to quality.

      Although I'm not sure what that has to do with rottable plastic...
      • Wish I had mod points... "Diode Gradation" was exactly what I thought.

        A quick Google search did reveal a paper on "Diodegradation of Cationic Surfactants" [scienceinthebox.com], which looked promising because of the "cation" (cathode/ion) reference. Alas, no other references to diodes [google.com] were included.

        Searching on the words separately yielded a Panasonic CD Receiver [panasonic.com], but no sites showed up with the term enclosed in quotes.

        Whatever. Now, I should probably go read the article before I go any farther off-topic. No +1 bonus for this reply!
  • Haven't goats been eating crap like that for years? We should just set the goats loose on the landfills.

  • Important part (Score:4, Insightful)

    by TheOnlyCoolTim ( 264997 ) <tim.bolbrock@veriz[ ]net ['on.' in gap]> on Wednesday December 04, 2002 @02:03AM (#4808182)
    Does the plastic *TASTE* sweet? If so, this might be a problem for use as utensils. Some foods don't go well with sugar.

    Tim
    • Have you ever tasted wood? It's made of cellulose, a sugar polymer. Doesn't taste anything like sugar, does it?

      Adding the sugar monomer is a very good idea to get the bacteria to break the long chains into smaller parts quickly. A nice idea, if I ever saw one. The question is: can such polymers be constructed so that they keep the same mechanical properties, at a low enough cost so that they are used...

  • Plastics sweeten YOU!
  • This was in my first year chemitry course:

    Cement should never be stored in bags previouly used to stored sugar because it weakens the cement.

  • Ants & other assorted insects (Score:4, Funny)

    by Spuffin ( 466692 ) on Wednesday December 04, 2002 @02:54AM (#4808376)
    I thought it was bad enough that insects try to eat your food if you leave it out on the counter, now they're going to eat the containers too.
  • Seeing as Plastic is going to be a favorite production material for a while now, this is good news. It's amazing that it took them this long to get this to work or to come up with the idea, whatever. This of course still won't help the bigger issues with heavy metals polluting the environment but it's a nice step in the right direction. If nothing else it has probably made a few more 'positive' jobs available.

    I'm also curious as to how this will effect plastic recycling? Are these new plastics recyclable? Do we really recycle plastics if we are trying to make more biodegradeable materials?

  • SO, lets make these plastics break down faster.. hmm good idea.

    Now we have lots of tiny microscopic bits of plastic floating around everywhere. Free for all to ingest in the water or air they breath. When all's said and done, I'd rather have an evian bottle laying on the sidewalk than floating in the air I'm breathing.

    What's the 1/2 life of the plastic molecules themselves? How toxic are they?

    What about the plasticizers (sp?) in the plastic. I believe they're some of the more carciogenic chemicals we've come up with.

    This sounds like a 2 edged sword moving in the wrong direction. Have I missed something?
    • What's the 1/2 life of the plastic molecules themselves?

      Uhhh, forever?

      I sure hope my coke bottles aren't radioactive.

    • Re:Plastics and, no, IN you (Score:4, Informative)

      by AJWM ( 19027 ) on Wednesday December 04, 2002 @01:28PM (#4811195) Homepage
      Have I missed something?

      Apparently.

      It doesn't break down into smaller pieces of plastic (well, it does, but that's a first step). The polystyrene chain is broken into smaller units as the bacteria attack the linked sugars. Those smaller units can then be broken down directly by the bacteria.

      Most plastics are poly-hydrocarbons (although stuff like PVC and teflon throw chlorine or fluorine atoms into the mix). Depolymerize them and you get hydrocarbons, which all sorts of bacteria find yummy (depending on the specific hydrocarbon -- but styrene and ethylene both occur in nature (styrene in strawberries, coffee, etc, and ethylene is a chemical trigger produced by and recognized by fruits to hasten the ripening process.)

  • Sweet Cables (Score:4, Funny)

    by droyad ( 412569 ) on Wednesday December 04, 2002 @08:14AM (#4809165)
    Wouldn't this create a bigger problem with vermin chewing on cables because they already taste good?
    • My cats already try to chew up every plastic thing and all our computer cables as it is. It is a startling site to see the cat munching on a power cable. If I every smell smoked kitty, I'll know the cause. :})||
      • We had a cat that chew threw an electrical cord. He got a good enough jolt that he wasn't able to let go of it. We had to hit the light switch.

        The cat just sat there confused for a second and then took off and hid. We didn't see him for two days. He finally came out to eat and was fine. He learned his lesson though. He never chewed on another wire until the day he died.
      • Tests indicate that cats can't taste sweetness, so you shouldn't have to worry. Of course, not being able to taste sweetness doesn't preclude a cat for liking sweet foods on other merits.

        Then again, my cats don't need any encouragement to chew plastic either. One of my cats just loves to chew the phone cord on the kitchen phone. I would coat it with pepper spray to make it taste awful, but it tends to bump him in the face at he plays with it while I talk on the phone. Now for computer cables, that would work really nicely. I'd suggest trying that.
  • Biodegradable plastics have been developed for some years now, however, the ones which have been released on the market degraded into pieces which small animals (squirrels, birds, etc.) choke on and die. I'm not sure how this novel modification may change this. We solve one problem, yet create other. Also the article doesn't go into much of the details which it referenced. The experiments which were performed used pure cultures of bacteria, which are not found in the natural environment (though will determine which bacterial strains are useful), and in liquid media flasks at 28 degrees celcius. How useful is that in rather temperate climates?
  • Wouldn't adding a substantial amount of sugar to plastic bits sortof decrease the specific heat radically? And, well, look at your computer. The case, the monitor, the shell. What's it made of? (not the aluminum/titanium/steel frame) PLASTIC! The monitor's shell is plastic, the bits on the fronts of drive trays are plastic, buttons, are plastic. Albeit, the heat generated wouldn't be enough to melt anything, even with 3% sugar onboard, but still. If this becomes such a good idea, and we opt to use a different type of sugar, which alters the heat even more, and you put it way too close to something that gets really hot... well...

    Melty 'puter. :-\
    • Read the article again. The types of plastics they give examples for are types most commonly used in plastic flatware, containers, and other disposable items that are rarely recycled or used in long-lived structures like toys and computers. Just because people have come up with this innovation doesn't mean it has to be used everywhere.
  • Could the sugars leech into food stored in these containers?
  • The article notes the volume of landfill space being taken up by plastics, and implies that this new plastics technology will solve the problem.

    But that ignores an important fact: nothing degrades in the landfill! To prevent groundwater contamination, landfills are lined and capped with impermeable materials that keep water out, and no water = no bacterial action.

    A poster in a previous discussion on landfills and biodegradability pointed out that you can open up a landfill and find 30-year-old newspapers, preserved just like new. Compare that with laying a newspaper out in your front yard. Degradable in the open, yes, Degradable in a sealed environment, no.

    Degradable plastics (however they decompose) are just another red herring to distract us from the real issues of truly sustainable development.

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