Thermosoftening Plastics (thermoplastics)
Thermosoftening plastics soften when heated and can be shaped when hot. The shape will harden when it is cooled, but can be reshaped when heated up again.
Easy way to remember: Thermosoftening. Goes soft when heated.
Thermosoftening plastics on the spec:
Thermosetting plastics have different properties to thermosoftening polymers. Once moulded, they do not soften when heated and they cannot be reshaped.
Easy way to remember: Thermosetting. Once it has been heated, it is set and cannot be changed.
Thermosetting plastics on the spec:
You will need to know and be able to draw the simple molecular diagrams for each type of polymer:
There are two classes of metal: ferrous and non-ferrous. Ferrous metals contain iron and therefore can rust, non-ferrous metals do not contain iron, and so they cannot rust.
Alloys are materials made from metals mixed with other metals or elements in order to gain specific properties. For example, stainless steel is an alloy made from steel and many other elements, including chromium. Chromium is added to make the steel resistant to rust.
Alloys can still be ferrous and non-ferrous, depending on what they are made up of. For example, brass is not ferrous because it does not contain any steel or iron.
An elastomer is a natural or synthetic polymer having elastic properties.
A ceramic is made of clay and permanently hardened by heat.
Pyrex (borosilicate glass) - made by heating certain raw materials to extremely high temperatures for extended periods of time. The molten material is then processed into different types of glassware, which when hardened, is heat proof, which makes it ideal for use in ovens and microwaves.
Porcelain - a white ceramic, commonly known as china.
A composite material is a material made from two or more constituent materials that when combined, produce a material displaying characteristics from both of the individual materials.
Carbon fibre -strong, lightweight, high strength-to-weight ratio, hard, expensive, corrosion resistant
Glass Reinforced Plastic (GRP) -hard, high strength-to-weight ratio, lightweight, strong, heat proof, corrosion resistant
Epoxy Resins (araldite) - adhesives (glue) made from a class of synthetic thermosetting polymers. Once set, it:
cyanoacrylates (superglue) - a type of quick setting adhesive (glue). Once set, they:
Shape Memory Alloys - metals that remember their original shapes.
- Used in wires in dental braces
Piezoelectric Actuators -Convert electrical energy into linear motion. They are very small and used in small applications.
- Used in products such as cameras.More information here
Optical Fibres - thin glass fibres through which light can be transmitted. They are very light and flexible.
- Used in broadband and internet cables as they are a quick and fast method of transmitting data.
Heat shrink Material - a type of plastic tubing that shrinks when heat is applied.