Urban pointed out that biological systems that can repair themselves may do so by either visible or invisible means. "Some we can see, like the skin healing and new bark forming in cuts on a tree trunk," he said in a press release.
"Some are invisible, but help keep us alive and healthy, like the self-repair system that DNA uses to fix genetic damage to genes."
The team, at the University of Mississippi's Urban Research Group, has worked on similar technology for several years. It has developed plastics with small molecular links that span the long chains of polymer's component chemicals.
The links break and change shape when the polymer is scratched or cracked. Modifying the links resulted in a visible color change when they change shape, forming a red blotch around the defect. (Watch a video of an accelerated similar self-repairing process, which doesn't change color first, here.) The links reform when temperature or pH changes, or when in the presence of ordinary sunlight or visible light from a light bulb.
Urban said that automobile fenders made of the new material that have become scratched could be repaired by being exposed to intense light. Structural components of aircraft could turn red where they have become cracked as a warning of damage. That would give engineers the choice of fixing the damage or completely replacing the component. He also cited several applications for battlefield weapons systems.
The team, which received funding for the project from the US Department of Defense, is currently working on incorporating the technology into plastics that can withstand high temperatures.
Ann, this is interesting. One thing I was thinking as I read this, though. One of the attributes of plastics is their low cost. One of the benefits of that is that you would replace the part rather than fix it. Taking that into consideration, how does the cost of this type of plastic compare to conventional plastics? I realize this is not in production yet.
Good question naperlou. You're right, this is not close to commercial development yet, so cost differentials are unknown. But since a self-healing plastic like this one--which unusually can self-heal multiple times--prolongs the life of the object many times, it means using less of it during that time. That cost amortization, as well as the benefits of not throwing away the object, implies that the COO to manufacturers would be lower than buying it once. I think the point here is that it's not aimed at high-volume, low-cost throwaway applications, but ones where continued use of a high-value product is important, such as military products or structural components.
Interesting story, Ann. I'm wondering if there are certain types of material damage that cannot be self-repaired. Your story mentions scratches. What about deformation caused by bending, particularly beyond the elastic limit of the material? If it could self-repair in those situations, it seems like it could be used in structural applications.
Thanks for the great article. naperlou makes a good point but I think the evolution of materials is moving away from convenience and towards true sustainability. The throw away culture we created in the early 20th century can't continue. Textiles made from pre and post consumer materials like milk fiber and wood bark were put on the shelf for the new thing--nylon. Now, we're dusting off that old research.
This sounds good but impractical for now. The cost and application make it very limited. if something like this could exist in medical devices, I'd be very impressed.
Looking forard to hearing more about this in the future.
Nadine, I think you're right about moving toward sustainability. But that's exactly what this could provide. Sustainable materials includes those made from greener materials (with lots of discussion about what that means), with greener processes (ditto), which can be recycled in various ways, and/or which can be used longer before being thrown away (or before being recycled). Sustainable materials can fulfill one or more of those 4 categories. This material can be classified in the last category.
We don't yet know how much more this plastic would cost, although it's being targeted at higher-priced apps, that's true. But after being developed for commercial production with those R&D dollars, it could then be extended and adapted to lower-cost apps, like medical. This is a common roadmap for new technologies.
@Ann-I completely agree. Cost is a major factor for mass market appeal. But, if the cost is the same or just slightly higher, it can fit into the general trend towards sustainability.
The article says that the plastic has to be exposed to intense light to heal itself. That's limiting for most medical implants but could be usuful in sports safety and performance enhancement equipment.
Nadine, intense light is one possible exposure mechanism--the article also mentions changes in temperature or pH. I'm not sure why strong light would be a problem for an implant, since an implant is usually kept away from light. Can you tell us more about what you mean?
Ann: I'm thinkiing specifically about joint replacement. I had the honor to attend an orthopaedic surgeons conference a few months ago. The technology is very interesting and has been making slow advances, especially in hip replacements. Even temperature and PH changes would be problematic for spine, knee and hip replacements.
But, it may cause less trauma than entirely replacing the unit.
Nadine, thanks for the clarification. Since this material is aimed at self-repairing surface damage, I don't think it's designed for implants. But that's an interesting idea. There are many biocompatible plastics made for that application, and designing one of those to be self-healing would be a good PhD project.
Ann, I liked your point about new medical applications for this technology. Many medical plastic components are constantly exposed to harsh sterilization chemicals during regular cleaning and maintenance procedures. If this self-healing process also works after a chemical exposure, it could be an interesting advancement for medical equipment designers.
Ann, first of all plastic is not an environmental friendly material. So most of the countries are trying either to reduce or ban the use of plastics. In such a scenario, what's the relevance of these types of thermoplastics? Is it something in an environmental friendly way?
ChasChas, thanks for that comment. I agree with you. I've reported on several other experimental materials that seem to be moving toward intelligence, some of them via nanotechnology, and many of them based on shifts in electrical charge.
Mydesign, most countries are trying to find alternate feedstocks for plastics, like bioplastics, and/or design plastics that are compostable or recyclable, as I've written about here
Meanwhile, these new plastics are only a drop in the huge bucket of the amount of plastics we consume. So extending the life of non-recyclable, non-compostable plastics by reusing them helps keep them out of the landfill.
It would be quite useful to know some of the more common materials propertiies of this self healing material, such as strength, stiffness, and temperature ratings, and that all important property, PRICE. My guess is that it would never be found in consumer goods evenif the cost were half that of styrene regrind. It appears that many consumer goods have avery intentional low quality level, so that they would be replaced every few months.
William, thanks for your comment. I agree with you about this not being likely for consumer-grade use. We addressed this issue earlier in the thread: since this is not close to commercial development yet, price and cost differentials are unknown. But self-healing plastics like this one--which unusually can self-heal multiple times--multiply the life of the object several times. Less plastic gets used during that time, so the COO to manufacturers would be lower than buying it once. It's not aimed at high-volume, low-cost throwaway applications, but ones where continued use of a high-value product is important, such as military or medical products.
The 100-percent solar-powered Solar Impulse plane flies on a piloted, cross-country flight this summer over the US as a prelude to the longer, round-the-world flight by its successor aircraft planned for 2015.
GE Aviation expects to chop off about 25 percent of the total 3D printing time of metallic production components for its LEAP Turbofan engine, using in-process inspection. That's pretty amazing, considering how slow additive manufacturing (AM) build times usually are.
A $1,500, hand-operated, bench-model, plastic injection machine crowdsource-funded via Kickstarter can be used to mold small, quality, plastic parts inexpensively, on demand.
The federal government is launching competitions to kickstart three more manufacturing innovation institutes, including one focused on Lightweight and Modern Metals Manufacturing Innovation.
The airframe of Airbus's A350 XWB consists of a bigger proportion of carbon-fiber-reinforced composite structures than any other commercial jet to date: over 53 percent by weight.
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