Some materials catch headlines, are held in awe, but not all. Some get little respect, despite having changed the world. They have become commonplace, anonymous, ignored, and (particularly if they are cheap) cast aside when no longer wanted. If they had feelings, they would be hurt. This brief series of blogs is to draw attention to their plight.
Some materials catch headlines, are held in awe, but not all. Some get little respect despite, in some cases, having changed the world. They have become commonplace, anonymous, ignored and (particularly if they are cheap) cast aside when no longer wanted. If they had feelings, they would be hurt. This blog is the first in a series designed to draw attention to their plight…
Completely new materials in the field of implantable devices are a rare occurrence. This is because of the heavy regulatory burden placed on implantable medical devices to ensure that they are safe and effective for use in the specified application. There has to be a very good reason to invest in the cost of qualifying a new material over the ones that have a long standing history in the field. However, one group of materials that seem likely to cross that boundary and have been gaining increasing attention in recent years are bioabsorbable magnesium alloys. But what are these alloys and why are they gaining such attention? Continue reading
Thomas Friedman has stated that ‘the world is flat’. He’s not recanting modern scientific discoveries, but he is highlighting that everything, everywhere, is somehow connected and that what happens at some part of the world can have drastic implications in other parts. It’s another way of saying that we live in a globalized world, that we eat, drink, and perform our daily activities using products that sometimes come from such remote places that we don’t even know they exist – take the horse-meat scandal as a recent example! It also means that the way in which we teach our younger generation has to adapt accordingly to this new paradigm of globalization.
Few products get a worse press than plastic shopping bags. They are distributed free, and in vast numbers. They are made from oil. They don’t degrade. They litter the country side, snaring water-birds and choking turtles. Add your own gripe.
Paper bags are made from natural materials, and they bio-degrade. Surely it’s better to use paper? And come to think of it, why not bags made out of jute – it’s a renewable resource – and use them over and over? That must be the best of all? Continue reading
There are some things that nature just gets right. Take bone, for example. This typically has an elastic modulus similar to concrete, but is 10 times stronger in compression and around 50 times stronger in tension. It has a compressive strength similar to stainless steel, but is three times lighter. Not only that, but as a living tissue, it can adapt to meet property requirements. Bones in the legs, such as the femur and tibia, are typically much stronger than bones found in the arm, for example. And its properties aren’t fixed: the graph below shows how bones change in behavior with age, as explored within Granta’s Human Biological Materials database. What’s more, bones adapt depending on external conditions – a constant challenge in space as bones weaken if they are not loaded (as happens in zero-gravity). Continue reading
Discovered in 1877 and patented in 1933, PMMA, or acrylic, is often used as a lighter, more shatter-resistant alternative to glass. It is easy to process and make, resulting in a low cost versatile material used for everything from windows in aquariums, to protecting the audience from stray pucks in ice hockey rinks, and even in shoes.
What is interesting about PMMA, though, is its biocompatibility. Despite being formed by polymerizing Methyl Methacrylate, an irritant, and possibly a carcinogen, PMMA is extremely biocompatible, resistant to long exposure to temperatures, chemistry and cell action of human tissue. Continue reading
The 22nd MMPDS Coordination Meeting was held last week (October 23-26), with members meeting to discuss the ongoing development of the Metallic Materials Properties Development and Standardization (MMPDS) data. But what is MMPDS, and who uses it? A good way to find out is to take one of the new materials in the latest release, and ask some questions about why it’s in there. Lightweighting is certainly a hot topic at the moment, so perhaps the lightweight aluminum beryllium alloy (AMS 7911) highlighted in MMPDS-06 would be a good example. Continue reading
Granta’s recent trip to MS&T in Pittsburgh, the Steel City, reminded me that this year marks a hundred years since the invention of stainless steel, or at least since the first patents were granted to Strauss and Maurer in 1912 for the austenitic stainless steel they branded Nirosta. At about the same time in Sheffield, England, Harry Brearley discovered a corrosion resistant martensitic alloy which, although designed for gun barrels, first found fame as the new, shiny entrance canopy material for the Savoy Hotel. Continue reading
A Silly Mistake?
No one set out to develop Silly Putty: it was a novelty by-product during research aiming at new silicone elastomers to replace scarce rubber. In 1943, an engineer at General Electric, James Wright, was working in the New Haven laboratory when he accidentally dropped boric acid into silicone oil: the result was a bouncing silicone putty. The new material stretched more than rubber, even at high temperatures, but it also had some more interesting and unusual properties. Over long timescales or at high temperatures it flowed like a fluid. But at shorter timescales it bounced and behaved like an elastic solid. GE started marketing it, but it only really took off when the novelty value of this new material caught the attention of Peter Hodgson, a marketing consultant. He bought the rights from GE, and started marketing his ‘solid liquid’ as ‘Silly Putty®’.