The different day it was convocation time right here at IIT Kanpur, the place I educate. The institute, the scholars, college, and all of the visitors who got here have been all dressed up in twinkling lights and smiles. An outgoing batch was to be congratulated, given some life recommendation, and lastly their levels.
My division head gave me a reasonably hurried name simply the night earlier than “Adhip, there’s a chance that some of us might must attend the formal programme sitting within the first few rows in the primary auditorium – would you be capable of sit there?’
Apart from my incapacity to remain awake throughout formal speeches, the primary fear right here was to seek out a clear and presentable set of garments that I might put on for the event. My treasure hunt for a clear kurta in my condominium did result in discovering one – the one downside was that it was wrinkled past recognition. As you is likely to be conscious, sporting a wrinkled costume to a formal occasion, resembling a convocation, could possibly be thought of a crime. So it was that at near midnight, I switched on my ironing machine and determined to offer my kurta a makeover.
The iron press
The iron press is a great machine. There are two necessary substances to this surprise: it has a heavy metallic base (usually some alloy of iron, thus the title) and that it heats up. Now, have you ever ever puzzled why our garments are straightened when ironed?
Our garments are made of some plant or animal fibres, like cotton, wool, and many others. Fibres are lengthy chain-molecules usually made of carbon, oxygen, and hydrogen – similar to the glucose and sugar that we eat (this doesn’t imply cotton is edible, nonetheless tempting your garments could appear).
These molecules may be actually, actually lengthy. If the water molecule, which is made of two hydrogen atoms and an oxygen atom, is the dimensions of a pencil, a typical cellulose fibre, one of the first molecules of cotton, could be about 100 metres lengthy! These sorts of molecules are referred to as polymers. Polymers make up many issues round us, together with plastic, cleaning soap, and even tomato ketchup. There are artificial polymers (made in a lab, like plastic) and then naturally occurring ones, resembling cotton.
When you wash your garments, these molecules turn into knotted round one another – like noodles once you cook dinner a packet, or your hair in the event you nonetheless have the privilege of having lengthy hair (not like most college members and a few college students right here). This is actually because of the water molecules that turn into caught between and round these molecules.
When you iron your material, what you might be actually making an attempt to do is rearrange these lengthy molecules into neat, straight patterns. In the method, some of these water molecules escape and evaporate. You will at instances discover a damp feeling if you end up ironing a material. Now you realize why.
Polymer physics
This mentioned, in the event you simply place a heavy weight on material and strive straightening it, it received’t work. Why is warmth required to realize this?
Heat is nothing however power: it causes all of the atoms and molecules to vibrate a bit and that does the trick. As we all know, every of these cellulose molecules could be very lengthy – and they will have varied twists and turns alongside their size, like one strand in a noodle.
Once in a explicit form, all of the atoms and electrons inside them organize themselves in a approach that they will have as low power as doable. But there may be one other approach of arranging comparable twists and turns in the identical system – like one other noodle in your pan – with a barely totally different power and even decrease than the earlier approach.
However, as soon as caught in a explicit sample, it is vitally tough for all of the atoms to maneuver collectively. They have little or no power to take action in addition to little wiggle room. The system is mainly in some intertwined state, just like chilly noodles or moist hair. You might have skilled this issue once you tried to maneuver a fork contained in the noodles or to maneuver a comb via tangled hair.
When you present warmth, these molecules get some power such that the molecular bonds vibrate and change their form. In the method, some of the water evaporates out. This is once more just like what you do once you need to replenish some meals grain in a container and there’s not sufficient area. You shake the field a little bit in order that the grains transfer round, cool down, and you discover some extra free area.
Similarly, right here, you present some warmth (or microscopic ‘shaking’) to trigger the molecules to make some speedy twist and turns. It is at this second that you just apply strain with the heavy metallic, eradicating the twists and turns and straightening the fibre up. Since the molecular twists and turns are considerably versatile when heated, they may do as you need. As quickly as you are taking the iron away, the molecules as soon as once more calm down and get caught within the straight sample you had left them in, leaving your material wrinkle-free!
Prof. Deepak Dhar
Of course, the warmth needs to be such that they solely transfer the atoms round, not a lot that they break the molecular bonds. Otherwise that is how it’s possible you’ll find yourself with a burnt gap in your costume.
In reality, totally different polymers have totally different temperatures at which they shake up the perfect, so totally different temperatures at which they are often most effectively straightened. This is why there’s a temperature dial on the iron. You will discover totally different material varieties marking how scorching the iron ought to get, relying on the polymer you might be ironing. This is as a result of the polymers have totally different chemical compositions.
For instance, on a regular basis plastic melts fairly simply – which is why folks keep away from placing scorching meals in a polythene container. Well, that night time my ironing did work and fortunately I awakened in time to attend the programme.
I heard the Infosys founder Mr. Narayan Murthy within the morning and Prof. Deepak Dhar within the afternoon – each visitors on the convocation right here.
Interestingly, Prof. Dhar is one of India’s most celebrated statistical physicists; statistical physics is a subfield of physics the place folks examine issues resembling polymers, which he had additionally finished in his personal analysis. If you need to study extra about his analysis and his life, you possibly can learn his great interview on the IIT Kanpur weblog, the place he additionally talks about his life as a pupil within the physics division.
The subsequent time you costume up for a get together or an event – resembling a convocation – and take a pair of ironed garments, simply bear in mind how the great physics of iron presses and polymers are doing their honest bit to create these joyous moments for you.
Adhip Agarwala is an assistant professor of physics at IIT Kanpur.
