Riding Aboard Japan's Super Fast Maglev Trian

Expanded PS

Polystyrene Boxes for Food

Concerns over the use of PS should best be analysed based on facts rather than on perception .

The fact that advanced countries like Japan , US and The EU continue to allow the use of PS as a food packaging material speaks volume about its safety .

Basically there are 2 forms of PS foam

·         Extruded polystyrene  [ foam plates , egg cartons  and other food food service applications ]

·         Expanded polysterene [ coffee cups , packaging of  delicate E & E appliances , consumer products ]

Both types are also used as thermal insulation in Industrial , commercial and residential construction.

[i]What is EPS?

EPS (Expanded Polystyrene) or as many know by The Dow Chemical Company's trade marked name, STYROFOAM, is an extremely lightweight product that is made of expanded polystyrene beads. Originally discovered by Eduard Simon in 1839 in Germany by accident, EPS foam is more than 95% air and only about 5% plastic.

Small solid plastic particles of polystyrene are made from the monomer styrene. Polystyrene is normally a solid thermoplastic at room temperature that can be melted at higher temperature and re-solidified for desired applications. The expanded version of polystyrene is about forty times the volume of the original polystyrene granule.

Expanded polystyrene (EPS) is a versatile, lightweight material that can be manufactured into a variety of products. EPS offers a high-performance yet economical support for a wide variety of items—from sensitive electronics to appliances to pharmaceuticals—to be safely delivered to market. Manufacturers rely on EPS packaging because of its ability to prevent or minimize product damage during transit and its excellent insulation properties required for food and medical shipments.

Yet EPS packaging, just like any disposable packaging, will eventually become a solid waste and have to be managed. But here’s the good news: EPS is recyclable. Although the availability of polystyrene recycling programs varies by community and can be limited, the EPS industry uses average of 50 percent of the post consumer material collected in the manufacture of new EPS transport packaging and loose fill packaging, which has reduced requirements for raw material resources, energy consumption has diverted material from landfills.

Smart materials - hydrogels

A hydrogel is a network of cross-linked polymers designed to absorb water.

It does this because it is hydrophilic.
In water, the polymer unit loses the Na+ ion and so the polymer becomes negatively charged as shown .

A long polymer chain usually curls up into a ball when in solution. However, when the Hydrogen atom is lost, the negative charges on the polymer chain repel.

The water then is attracted to the negative charge and hydrogen bonding occurs. The polymer can absorb up to 300 times its own mass in water.

Three major uses for hydrogels are: disposable nappies, water crystals for plants and hair gel.

Source : Robertcampbelluas edublog

Keeping in touch with latest materials !

Smart Materials 

A Smart material is a material that can change its properties when there is a change in it’s environment. Examples of external stimuli that can change are: pH, temperature, stress, pressure, water content / moisture, light etc

Shape memory metals

A metal that ‘remembers’that it is meant to be a certain shape. The material can be easily bent (deformed) then under a reasonable temperature moves back to its original shape.

Smart memory metal are very useful because they are reliable (they do the same thing every time) and repeatable (we can do it over and over again).

The SCIENCE behind them: 

Shape memory alloys have two crystal structures that the metal transfers between via a molecular rearrangement. In a molecular rearrangement, the solid state phase changes but molecules remain closely packed and therefore remain solid. The 2 phases are known as Martensite and Austenite.

The Martensite is soft and easily deformed.

You can see clearly the different crystal structures.  When the Austenite cools its crystal structure changes This is known as the martensitic transformation.

Uses

All the things that we want to move once done with a motor or lever, we can now do with smart metals. These are low cost, low mass, smaller in size resulting in lower energy consumption.

Medicine – doctors use memory alloys to treat broken bones. The alloy is cooled then wrapped around the broken bone. Body temperature warms up the metal so it goes back to its original shape thus pulling the bone together and holding them in place while it heals.

The same thing happens for braces.

http://robertcampbelluas.edublogs.org/shape-memory-metals/

ScienceCasts: Genius Materials on the ISS

Key Properties of materials

Different materials exhibit different working properties. Listed below are the key properties which determine how materials behave.

• conductivity is the ability of a material to conduct heat or electrical energy
• strength is the ability of a material to withstand a force without breaking or bending
• elasticity is the ability of a material to bend and then to return to its original shape and size
• plasticity is the ability of a material to permanently change in shape
• malleability is the ability of a material to permanently deform in all directions without cracking
• ductility is the ability of a material to deform, usually by stretching along its length
• hardness is the ability of a material to resist wear, scratching and indentation
• toughness is the ability of a material to withstand blows or sudden shocks without breaking
• durability is the ability of a material to withstand wear, especially as a result of weathering
• fusibility is the ability of a material to change into a liquid or molten state when heated to its melting point

Source : http://www.bbc.co.uk/schools/gcsebitesize/design/resistantmaterials/materialsmaterialsrev6.shtml

Smart materials

Smart materials are reactive materials. Their properties can be changed by exposure to stimuli, such as electric and magnetic fields, stress, moisture and temperature.

Smart colours

Smart colours are pigments which can be incorporated into paints, dyes, inks and plastics.

• thermochromic pigments react to changes in temperature
• photochromic pigments react to changes in light levels

Photochromatic materials are used in the manufacture of sunglasses. Exposure to sunlight causes the lens of the glasses to darken to protect the eye.

Conductive polymers

Most plastics are natural insulators. The advantages of making plastics which areconductors are:

• they are easier to manufacture
• they are lighter and cheaper than metals
• they prevent the build-up of static electricity which can damage microcircuits

Some conductive polymers are also biocompatible, making them suitable for use in medical devices.

Nanomaterials

Nanoparticles improve the mechanical properties of a material, such as stiffness or elasticity. When incorporated into polymers, they can be used as lightweight replacements for metals.

Nanomaterials are used in car manufacturing to create cars that are faster, safer and more fuel efficient. They can also be used to produce more efficient insulation and lighting systems.

http://www.bbc.co.uk/schools/gcsebitesize/design/resistantmaterials/materialsmaterialsrev6.shtm