Unusual material

Relaxation time

Unusual material

In nature - many interesting and unusual substances and materials with amazing properties. The exhibition of such materials were represented an unusual material, which in outward appearance resembled rubber or even clay. It can be knead, to press, to sculpt the shape. The material had great elasticity and plasticity. But to everyone's surprise, when he made a ball and threw it down, then it does not stick to the floor, but bounced almost to the same height from was thrown - like a rubber ball. If this material to stretch in a long plait, and then abruptly pulling the ends, - the wiring will burst with a considerable bang! You canagain do a shape from it into a ball and push with hammer - ball will shatter into small pieces. But these fragments can be easily assembled and you can again do a new same ball. This unusual material was the result of a mistake or even the synthesis of special polymer that tried to get American scientists then to give him certain strictly aimed specific properties! But the new resulting material is not what scientists wanted. The result of this synthesis were suitable only for sale at the toy store.

From this experiment it can be concluded that it is not always possible to say with precision whether the presented material is solid or liquid. Even in the 19th century it was suggested that liquid and solid bodies do not have clear boundaries. If you think about it, there is nothing particularly surprising. If, for example, to hit the water with palm, the water will behave as a solid body (optionally, you can feel it!). If you hit with a hammer on the stream of thick fluid, with small exposures the camera can capture the impact the jet will break into many sharp pieces crayons (drops) that tells about some of the properties of solid, as a brittle bodies.

unusual material, water sprays
Bullet breaks a jar of drink, spray flying like small pieces of glass

Or if you take a piece of resin, glass - are amorphous materials. They're so viscous that the flow properties of these materials are not visible. Actually, they flow, and it can be easily identified with attaching there the force! (of course, glass - more viscous substance and the manifestation of the properties of the flow it require more individual conditions, such as heating or long time of force).

Why is it happening?! It turns out it's all about the exposure time for the material. There is the concept of relaxation time molecules, in other, is the time required for the molecule to move (react) impact. If relaxation time molecules of the substance significantly more time exposure to the substance, the molecules do not have time to readjust (move) with force that leads to break down of chemical bonds in the material. For different materials relaxation time is different and can change in very wide limits: from thousandths of a second to several millennia.

The greatest interest is the substance the molecules of which do not have such a large relaxation time, such as the hardened resin, but not so small as is the water.It is to such substances are our polymer - unusual material. Its elastic properties are manifested at an elevated temperature ( like a metals), and other properties - at room temperature: if the force be applied slowly - it is as a viscous liquid, if rapidly - like rubber and if with very fast - shows brittle properties!

Consider unusual material like a chemical composition. It may consist of 0.5 - 7.5% of boron, included in the boron group - O-B-O-. Included the structural chain (—(CH3)2Si—Η)n make it accessories to the silicone caoutchouc. Boron-containing groups are the connecting links for the silicone chains. Like a many polymers, the molecular weight of such material may vary from hundreds to tens of thousands of mass units, so, the aggregate state changes from liquid to solid. It is known if the material is with not very high molecular weight (consists of a not very large number of chains), at room temperature is able to spread. With increasing molecular weight - become the solid, elasticity and jumping ability. When falling on a hard surface, able to jump almost at the same height.

The property of elasticity of some liquids can also be observed if, for example, to tilt a glass with this liquid to the side. The liquid will flow slowly on the edge of the glass. But if the glass is sharply tilted in the other side, the fluid flow will continue! Water, of course, such experience does not pass because the water has not enough elasticity.

To do such experiments at home do not necessarily produce or procure, or to synthesize unusual material. You can use ordinary condensed milk. It's funny, but you can use honey, and some shampoos - these substances have an unusual relaxation time.If the jet to cut with scissors, the lower part will fall down and upper - back into the tank, from where have emerged.
Here's another experience: if the shampoo with sufficient thickness to fill with a saucer trickle, then soon you will notice that the stream that fell down, starts to curl, like a rope (on top of the poured shampoos), to squirm and even sliding down. This is shown that the shampoo has the property of rubber!
A fun experience with a silicate glue (water solution of sodium silicate) and ethyl alcohol:

In small container pour a little (10 ml) of glue, and then added, continuously stir. After the liquid turns into jelly, extracted it and sculpt the ball, wash it with water (don't forget to wash the dishes from the glue!). We got elastic silicagel (chemical formula SiO2•nH2O). It has all the properties of unusual material: if the force be applied slowly - it is a very viscous liquid (or even clay, you can knead by hand), if you leave the bulb on a hard surface - it will spread, at the same time, if to hit on a hard surface bounces like rubber and if to hit stronger - crumbles. But still, over time, the silicagel dries out, becomes brittle and, of course, loses almost all its properties.