DP1 Unit 3 Part 1 - A3.1 Material Properties

synthetic

not naturally produced; made by artificial processes

polymer

A large molecule formed from many smaller molecules like building blocks

composite

made up of separate parts

plastic

a synthetic material made from polymers like PVC, nylon, etc.

alloy

A mixture of two or more metals

textile

A fabric made by weaving, used in making clothing

physical property

A characteristic that can be observed without changing the material

chemical property

A characteristic that describes its ability to change chemically

mechanical property

Any of the physical properties of a material that change when force is applied

Density

A physical property defined as the amount of mass per unit volume (Mass per unit volume of a material (e.g., kg/m³ or g/cm³). Important for product portability and weight.

D = M / V --> Density = Mass / Volume

Thermal expansion

A physical property defined as the tendency of a material to change its dimensions (length, area, or volume) in response to a change in temperature.

Thermal conductivity

A physical property defined as the ability of an object to transfer heat. This is a measure of how fast heat is conducted through a material. High = good conductor; low = good insulator.

Melting point

A physical property defined as the temperature at which the material changes from solid to liquid

Electrical resistance

A physical property that resists the flow of an electric current

Electrical conductivity

A physical property defined as the ability of an object to carry electric current

Corrosion Resistance

A chemical property defined as the ability to withstand deterioration from environmental factors.

Reactivity

A chemical property defined as how easily a substance combines chemically with other substances (such as baking soda and vinegar)

Hygroscopy

A chemical property defined as the ability to attract and hold water molecules from the surrounding environment

Tensile strength

A mechanical property defined as being able to resist breaking under tension

Malleability

A mechanical property defined as the ability to be hammered or beaten into thin sheets

Elasticity

A mechanical property defined as the ability to bounce back after being changed (bent, pulled, etc)

Plasticity

A mechanical property defined as the ability to be deformed permanently without breaking

Compressive Strength

The ability of a material to withstand being pushed or squashed (axial loads) without failure.

Stiffness

A material's ability to resist bending or deflection and maintain its shape; the ratio of stress to strain.

Toughness

The ability of a material to absorb energy and resist the propagation of cracks without fracturing. The opposite of brittle.

Hardness

The resistance of a material to scratching, cutting, or indentation.

Malleability

The ability of a material to be plastically deformed under compressive force (e.g., hammered into thin sheets). Gold is the most malleable metal.

Elasticity

The ability of a material to return to its original shape after being deformed, once the applied force is removed.

Ductility

The ability of a material to be drawn or extruded into an extended shape such as a wire under tensile stress. Copper is a very ductile.

Corrosion Resistance

The ability of a material to withstand damage caused by oxidation or other chemical reactions with its environment.

Flammability

A measure of how quickly a material can be ignited and how rapidly it will burn.

Hygroscopy

A chemical property describing a material's ability to absorb moisture from the surrounding environment.

Reactivity (food safety)

The extent to which a material will react with another substance, including air, to become unsafe for food contact.

Melting Point

The temperature at which a material transforms from a solid to a liquid.

Electrical Resistivity

The measure of how strongly a material opposes the flow of electric current. High resistivity = insulator.
Rubber is a good insulator.

Electrical Conductivity

The measure of a material's ability to conduct electricity. High conductivity = good conductor. Copper is a strong electrical conductor.

Composite Material

A material made from two or more constituent materials with different properties, combined to create a material with superior characteristics.

Stress

Force applied over an area (measured in Pascals).

Strain

The resulting deformation (a dimensionless ratio).

Young's Modulus

The ratio of stress to strain in the elastic region and indicates stiffness.

Tensile

Pulling/stretching a material apart.

Compressive

Pushing/squashing a material together.

Shear

Forces pushing sideways in opposite directions.

Torsion

Twisting forces applied to a material.

Bending

A combination of tensile and compressive forces causing deflection.

Mohs Scale

Ranks minerals 1-10 by scratch resistance. Diamond = 10.

Stainless steel

Metal alloy made from iron, chromium, carbon and other minerals. Valued for its corrosion resistance.

Rubber

A flexible, elastic material with high electrical resistivity (good insulator)

Diamond

The material with the highest rating on the Mohs hardness scale, often used to coat the tips of metal cutting tools because of its extreme hardness.

Photochromic - Smart Material

Materials that change in response to light

Non-hygroscopic

Unable to absorb moisture from the environment easily, such as PVC and other polymers

Thermosetting Plastics

Plastics that resist deformation when heated, and can only be molded once. When they are heated the first time, they are chemically changed so that they become permanently hard and rigid. For example: epoxy resin (ER), melamine, urea-formaldehyde (UF - which you might know from the plastic shape around a socket)

Thermo-forming Plastics

Plastics that don’t resist heat well, and can be easily deformed by heating, melting and remolding. Because of this, they are easy to recycle. Examples include acrylic, high density polyethylene (HDPE), polyethylene (PET), polyvinyl chloride (PVC) and polypropylene (PP)

Ceramics

A unique class of materials that are hard and strong but not tough. They are not easily scratched, have high compressive & tensile strength, but are brittle when hit by a blunt force.

Brittle

Opposite of toughness

Shape memory alloy - Smart Material

A material which can be moulded and return back to its original shape once heated e.g. glasses and springs

Magneto-rheostatic - Smart Material

A type of fluid that changes viscosity when exposed to a magnetic field, often used in dampers and robotics

Electro-rheostatic - Smart Material

A type of fluid that changes viscosity when exposed to an electric field, often used in dampers and sensors.

Piezoelectric - Smart Material

The ability to convert pressure into electricity and electricity into pressure

Thermoelectric - Smart Material

A material that generates electricity when subjected to a temperature difference, used in applications such as cooling systems and generating power.