Check the knowledge of active vocabulary from this part with the help of “active vocabulary” section. Part II

1. Smart materials (1) Read the following text and fill in the gaps. Use the words given in boxes:

temperature materials types magnetic properties

Smart materials are (1) __________ that have one or more (2) __________ that can be significantly changed in a controlled manner by external stimulation, such as stress, (3)__________ , moisture, pH, electric or (4) __________ fields.

There are different (5) __________ of smart materials, some of which are already common. Some examples are as following:

environment produce changes field from shape

• Piezoelectric materials are materials that (6) __________ a voltage when stress is applied. Suitably designed structures made (7) __________ these materials can bent, expand or contract when a voltage is applied.

• Shape memory alloys and shape memory polymers are thermo-responsive materials where deformation can be seen in case of temperature (8) __________.

• Magnetic shape memory alloys are materials that change their (9) __________ in response to a significant change in the magnetic (10) __________.

• pH-sensitive polymers are materials which collapse when the pH of the (11) __________ changes.

• Temperature-responsive polymers are materials which changes depend on temperature.

  pressure metal opacity colour sunlight response electrical

• Halochromic materials are commonly materials that change their colour as a result of changing acidity. One suggested application is for paints that can change (12) __________ to indicate corrosion in the (13) __________ underneath them.

• Chromogenic systems change colour in response to (14) __________, optical or thermal changes. These include electrochromic materials, which change their colour or (15) __________ on the application of a voltage (e.g. liquid crystal displays), thermochromic materials change in colour depending on their temperature, and photochromic materials, which change colour in response to light - for example, light sensitive sunglasses darken when used in bright (16) __________ .

• Non-Newtonian fluid is a liquid which changes its viscosity in response to an applied shear rate (to shear = to become twisted or break under pressure). In other words the liquid will change its viscosity in (17) __________ to some sort of force or (18) __________ .

• Ferrofluid

• Photomechanical Materials change shape under exposure to light.

2. Smart materials (2)

Read the text and fill in the gaps. Use the words given in the box:

solid design alloys changed special shape technology properties type smart

Science and (1) __________ have made amazing developments in the (2) __________ of electronics and machinery using standard materials, which do not have particularly (3) __________ properties (i.e. steel, aluminum, gold). Imagine the range of possibilities, which exist for special materials that have properties scientists can manipulate. Some such materials have the ability to change (4) __________ or size simply by adding a little bit of heat, or to change from a liquid to a (5) __________ almost instantly when near a magnet. These materials are called (6) __________ materials. Smart materials have one or more properties that can be changed. Most everyday materials have physical (7) __________ , which cannot be significantly altered; for example if oil is heated it will become a little thinner, whereas a smart material with variable viscosity may turn from a fluid which flows easily to a solid. Different smart materials already exist, and are being researched extensively. These include piezoelectric materials, magneto-rheostatic materials, electro-rheostatic materials, and shape memory (8) __________ . Some everyday items are already incorporating smart materials (coffee pots, cars, the International Space Station, eyeglasses) and the number of applications for them is growing steadily. Each individual (9) __________ of smart material has a different property which can be significantly altered, such as viscosity, volume, and conductivity. The property that can be (10) __________ influences what types of applications the smart material can be used for.