Paper, Plastic, or Jute: what’s best for shopping bags?

carrier-bagsFew 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

No match for nature? The amazing properties of bone

boneThere 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

Poly(methyl methacrylate): a biocompatible acrylic

medicalDiscovered 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

Lightweight aluminum beryllium alloys

MIThe 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

100 Years of Stainless Steel

oil-rigGranta’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

Green is the new Gold

rohsRegular readers of this blog will know all about gold. Now I’m going to talk about why green is the new gold, focusing on why companies are trying to deliver greener products, and providing some tips for how to do it.

Why greener products make good business sense

Companies often find that trying to lower the environmental impacts of their products also leads to lower manufacturing costs, through the reduction of materials, energy and waste. For designers, thinking about sustainability issues can offer a new and fresh perspective on the products they develop—helping them to spot opportunities for waste and cost reduction. Smiths Detection provide a good example of this. When redesigning an existing product with sustainable design principles in mind they were able to save nearly $160,000 per year in manufacturing costs (download the case study in PDF format here). Continue reading

The Not-So-Silly Science of ‘Silly Putty’

sillyputtyA 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®’.

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A Materials Take on Going for Gold

goldAs the 2012 Olympics open in London this week, athletic achievements, and gold medals in particular, are drawing everyone’s attention. At the original Olympics in ancient Greece, the winner simply received an olive wreath: when the games first restarted in 1894, winners received a trophy. For most of the recent Olympic history, however, the crowning glory of any athletic career has been the Olympic Gold Medal. But behind the excitement of                                             sporting prowess, we wanted to know more about the gold in the medals                                         themselves.

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