A3.1 Material Classification and Properties

Bio-materials

Any material created by, or derived from, biological organisms, including plants, animals, bacteria and fungi.

Chemical properties

A property of a material that only becomes evident during or after a chemical reaction.

Circular economy

An economic model in which resources remain in use for as long as possible, from which maximum value is extracted while in use, and the products and materials are recovered and regenerated at the end of the product life cycle.

Composite material

A material comprised of two or more materials to improve their physical, mechanical and chemical properties and/or aesthetics characteristics.

Compressive strength

The ability of a material to withstand being pushed or squashed.

Corrosion resistance

The ability of a material to withstand damage caused by oxidization or other chemical reactions.

Density

The mass per unit of volume of a material. Its importance is in portability of a product's weight and size. Design contexts include food packaging, because pre-packaged food is sold by weight and volume, and packing foams.

Ductility

The ability of a material to be drawn or extruded into an extended shape such as a wire.

Elasticity

The extent to which a material will return to its original shape after being deformed, once the force causing the deformation is removed.

Electrical resistivity (electrical conductivity)

The measure of a material's ability to conduct electricity. A material with low resistivity will conduct electricity well.

Electro-rheostatic

This smart property relates to a fluid that can undergo a dramatic change in its viscosity when exposed to an electric field. This effect is reversed when the electric field is removed.

Flammability

A measure of how quickly a material can be ignited and how quickly it burns.

Hygroscopy

A chemical property of a material that has the ability to absorb moisture from the surrounding environment.

Glass

A hard, brittle and typically transparent amorphous solid made by rapidly cooling a fusion of sand, soda and lime.

Hardness

The resistance a material offers to penetration or scratching.

Magneto-rheostatic

This smart property relates to a fluid that can undergo a dramatic change in its viscosity when exposed to a magnetic field. This effect is reversed when the magnetic field is removed.

Malleability

A material's ability to be plastically deformed under compressive forces.

Manufactured material

A material that does not occur naturally in the world. It is synthetic or artificial.

Mechanical properties

Properties of a material that involve the relationship between stress and strain or a reaction to an applied force.

Melting point

The temperature a material transforms from a solid into a liquid.

Natural materials

Materials that occur in the natural world.

Photochromicity

A property of a smart material. A photochromic material changes colour in response to an increase in light. When the light source is removed, it returns to its original colour.

Physical properties

Any property that is measurable and that describes a state of materials, including density, thermal expansion, thermal conductivity, melting point, electrical resistivity and electrical conductivity. These properties tend to be the characteristics of materials that can be identified through non-destructive testing.

Piezoelectricity

A property of a smart material. A piezoelectric material gives off a small electrical discharge when deformed and experiences an increase in its volume when an electrical current passes through it.

Plasticity

The ability of a material to be changed in shape permanently.

Polymer

Synthetic materials made from chemical compounds commonly referred to as 'plastics'.

Reactivity (food safe)

A chemical property of a material that represents the extent to which a material will react with another (including air) to become unsafe for use to come in contact with food.

Shape memory material

A material that 'remembers' and returns to a predefined shape after being deformed. This is achieved in response to changes in temperature or stress.

Smart materials

Materials that have been designed to have one or more properties that can be modified when subject to an external stimulus in a way that the output can be controlled. This modification (change) is reversible and can be repeated.

Stiffness

A material's ability to resist deflection (bending deformation) and maintain its shape.

Tensile strength

The ability of a material to withstand pulling forces.

Textiles

A cloth or woven fabric material.

Thermal conductivity

The measure of how fast heat is conducted through a slab of material with a given temperature difference across the slab.

Thermal expansion

A measure of the degree of increase in dimensions (length, area or volume) when an object is heated.

Thermoelectricity

This refers to a smart material comprised of two dissimilar conductors that produce an electric current when heated.

Timber (lumber)

Wood harvested from trees prepared for use in manufacturing, construction and carpentry. Categorized as softwoods and hardwoods depending on the type of tree it is sourced from.

Toughness

The ability of a material to resist the propagation of cracks.