Material categories and properties - AQAPhysical and working properties

Each material has properties that make them good for specific tasks, eg cotton is lightweight and absorbent. The properties of materials must be considered when designing a product, eg a steel pan handle would conduct too much heat and burn the user, whereas beech would be more appropriate as it is tough but a poor conductor of heat.

Physical properties:

• absorbency - the ability to soak up moisture, light or heat, eg natural materials (such as cotton or paper) tend to be more absorbent than man-made materials (such as acrylic or polystyrene)
• density - how solid a material is. This is measured by dividing mass (grams) by volume (cm³), eg lead is a dense material
• fusibility - the ability of a material to be heated and joined to another material when cooled, eg webbing is fusible and can be ironed onto fabrics
• electrical conductivity - the ability to conduct electricity, eg copper is a good conductor of electricity
• thermal conductivity - the ability to conduct heat, eg steel is a good heat conductor, whereas pine is not

Working properties:

• strength - the ability of a material to withstand compression, tension and shear, eg in woven fabrics cotton isn’t as strong as wool when pulled
• hardness - the ability to withstand impact without damage, eg pine is easier to dent with an impact than oak; therefore, oak is harder
• toughness - materials that are hard to break or snap are tough and can absorb shock, eg Kevlar in bulletproof vests is a very tough material
• malleability - being able to bend or shape easily would make a material easily malleable, eg sheet metal such as steel or silver is malleable and can be hammered into shape
• ductility - materials that can be stretched are ductile, eg pulling copper into wire shows it is ductile
• elasticity - the ability to be stretched and then return to its original shape, eg elastane in swimming costumes is a highly elastic material