Plastics and Polymers

We use plastic bags all the time, they're cheap, so most people just throw them away, but not the green consumer plastic bags are thin and light. How much punishment can they take? Why is it a good idea to reuse plastic bags and what problems might there be? What are plastics anyway, plastics are artificial. They don't grow on trees, they're part of a wide range of materials called polymers. There are natural polymers t-shirts are made from cotton, which is a natural polymer. Bananas are full of polymers, so some polymers do grow on trees. One property of most polymers is that they're quite tough, which is why you can't eat banana skins. Another thing that's full of polymers is grass. We can eat grass if we really want to, but we can't digest it. Sheep have a secret weapon. They can digest grass because they've got several extra stomachs and the right chemicals to break down the polymers grass is tough, but it's only strong in one direction, which way is it easier to tear a blade of grass is made from long thin fibers, which all grow? In the same direction, this is the scientific eye paper tearing team to see exactly how they tear takes a scientific eye after the Tedder pit. This way, you can see the fibers going up and down so it'd be easy to tear along the fibers. This way, when you hold the pepper the other way around, you can see the fibers going across, which wouldn't be easy to tear. It would make a jagged edge. So I predict that if you turn along the fibers you'll get a straight line. Is she right across the fibers, you could get a jagged edge after the Tedder pit. This way, then you'll get a jagged edge. What do you think rapunzel rapunzel, let down your hair? How strong is hair? Could it support a knight in shining armor, or should he at least have left his horse on the ground? Hair is another polymer. Do you think fair hair is stronger than dark hair? This is nylon. Fishing line. Nylon is a polymer invented by a chemist. One strand is probably stronger than the average ponytail. Not all polymers are strong, bubblegum is airtight and it has some other interesting properties as well. It'S stretchy and it's sticky. What other polymers are there and what properties do they have? This scientist is making an artificial polymer. The reaction is one example of polymerization it's expanding, because the reaction also produces a gas. The gas is trapped inside bubbles of the forming polymer. So what you end up with is a plastic foam. Let'S look at what makes up a polymer, and here they are introducing the monomers in the liquid. There are millions of them all floating around separately when they polymerize the monomers link up into long chains. Now they're polymers, when the long chains become tangled together, they're hard to unravel, and that's one reason why polymers are strong once you know how to make polymers. It'S amazing what you can turn them into discovering how to make polymers was good news for elephants back in the nineteenth century, whenever snooker players needed more balls, they had to make them from ivory. A $ 10,000 prize was offered to anyone who could invent a substitute and the scientist who potted it in 1872 was JW Hyatt. He created the first synthetic polymer and called it celluloid, and it proved to be perfect not only for snooker balls, but also for ping pong balls and the backing for photographic film. Another polymer they had problems with back in the 19th century was rubber. Under the hot Summer Sun 19th century rubber got sticky. What was needed was a way of improving rubber, so it wouldn't melt Charles Goodyear conducted hundreds of experiments by mixing rubber with other chemicals, but discovered the solution by accident. The new material he'd invented was exactly what he was looking for. The chemical he'd mixed in with the rubber was sulphur. When this mixture was heated, the sulphur formed links between the polymer chains in the rubber. This made it even more difficult for the chains to move, so the rubber was less easy to melt. Cross-Linking with sulfur is called vulcanization, so thanks to Charles Goodyear, everyone came on stuck what are the useful properties of rubber and why might melting be useful in making plastic products? This sheet of hot plastic is about to become a bath. One way of making plastic products is to heat a sheet of plastic until it's flexible and then use a vacuum to form the plastic into the shape you need. This process is called vacuum forming, as the vacuum pump removes the air from underneath air pressure above forces. The softened plastic down onto the mold polymers, which soften when you heat them, are called thermoplastics. You can test to see if something is made from thermoplastic by reheating it thermoplastics have a memory. They will try to return to their original shape. Do you think this yogurt part will remember it was once a flat disc, almost Total Recall the scientific i-team safety. Okay are here to find out whether a bathroom shower tray has any memory, after only a few minutes at 200 degrees, it's as flat and floppy as a pancake Victor to go. Not all polymers come in sheets. There'S a polymer spray coming out of the bottom nozzle. Here and a stream of glass fibers coming out at the top to make a smooth plastic bath strong, they cover the outside. With this composite of polymer, resin and fiberglass. Why do you think composite materials might be strong? Eggs are full of polymer polythene granules, the raw material for making polythene bags. The granules are pushed along by this Archimedes screw and into an oven where they melt. The pressure and temperature are carefully monitored. The polythene is forced out through a ring and sealed at the top to make a balloon. It'S tied with a piece of string and pulled up to the roof. Air is blown up, the middle, which keeps the growing tube inflated the liquid polythene solidifies within 30 centimeters. The tube cools down and is drawn between sets of rollers. How do you think they turn this flat tube into plastic bags, whatever product you make, you need scientists to look after quality control. This machine measures the coefficient of friction between two sheets of polythene. Why would anyone want to know how slippery it is, and who is this test aimed at any material left over, goes through the company's own recycling system? The plastic is melted in an oven. Then it's converted into granules, which are washed with cold water and sent back to the start of the production line. Recycling is good for the environment, but it also saves the company money. What about your work?