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Is ‘The Blob’ a rheology fright night movie?

30 October 2012 One Comment

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If you take a listen to the theme tune for the 1958 B-movie classic ‘The Blob’, you’ll hear a song that sounds bizarrely cheerful and frivolously upbeat, for a film that has probably been the cause of recurring night terrors for many!

Consider some of the words of that song – ‘Beware of the Blob, it creeps, and leaps, and slides and glides…..’ – against a plot of a meteorite that comes to Earth and disgorges a thick viscous mass that oozes from the broken shell, which shows self-locomotion and can move up vertical surfaces, and grows at an unerring rate on a diet of humans, such that it threatens to engulf small town America.

So, aside from having the right attributes to scare the pants (US terminology) off teenage Drive-In audiences, ‘The Blob’ itself also has many attributes of a complex non-Newtonian material – apart from its longing for the taste of human flesh that is! Were the writers inspired for the creation of this monster by recollections of rheology from a graduate school course by any chance?

The thick viscous gel-like mass that becomes more and more mobile suggests a thixotropic structure that thins down and has a quick re-build time. Generation of high normal forces in the non-linear regime could help explain those extreme climbing capabilities. Since ‘The Blob’ never leaves a trail, it also suggests that its gel-like structure is stable to syneresis.

Not only do rheological properties like the above make a genre-defining B-movie monster, they are also some key characteristics for today’s rheologically-engineered complex fluid and soft solid products – which range from novel synthetic biomaterials to low fat food products, and from personal care formulations to coatings and speciality chemicals. Rheology really is everywhere!

And how was ‘The Blob’ ultimately ‘defeated’? When our heroes Steve (Steve McQueen!) and Jane take refuge from the gelatinous mass in the walk-in freezer of a grocery store, ‘The Blob’ does not follow beyond the door threshold. Then later, after seeing it recoil after aiming a carbon dioxide fire extinguisher at it in desperation, Steve realizes that cold can stop the unstoppable – “That’s why it didn’t come in the icebox after us! It can’t stand cold!” Rheological properties, are a strong function of temperature – a test on a rheometer would have undoubtedly revealed the temperature at which the dynamics of ‘The Blob’ become slow enough to stall it.

Eventually frozen solid by the local High School students using every carbon dioxide fire extinguisher in the school, ‘The Blob’ is boxed up by the US Army and dropped at the North Pole – safe “as long as the Arctic stays cold”. But did that ominous question mark that ended up slithering across the screen suggest ‘The Blob’ knew about global warming……??

If you’re still unsure as to whether non-Newtonian fluids make terrifyingly beautiful monsters, see the response of a shear-thickening material to a forced deformation with a free surface (the scary stuff is from time 2:00 onwards) – and this footage is perfectly set to music from ‘The Blob’!

Do take comfort in the thought that as the dark shadow of Halloween looms large, maybe a little rheology knowledge can help you out, with some of the monsters at the door at least……..