PLASTICS - Thermoplastics and Thermosets

PLASTIC - a recent manufactured product

Plastic Is a very new material, compared to wood and metal. It has only been available over the past 50 years or so. Since then it has been used to produce toys, guttering. bottles, bags and thousands of other everyday products. These items simply did not exist 1 or 2 generations ago!

Most plastics are produced from oil. They vary a lot, in the way they are made and can be either rigid or flexible. Depending on what plastics are needed for they can also be strong, hard or soft for clothing etc.

One big disadvantage to the plastic/ acrylic that you will be making things from,is that it is brittle (breaks easily).

TYPES OF PLASTiCS

Plastics are divided Into 2 groups: THERMOPLASTICS and THERMOSETS

The word “thermo” means heat e.g. thermometer, thermostat etc. The way that a piece of plastic reacts to heat determines the group it belongs to.

Thermoplastics soften once heated. They can be re-heated and re-shaped again and again.

Thermosets are SET once they have been produced. They do not soften once re-heated; in fact they harden. Furthermore, thermosets cannot be used again.

Common Thermoset and USES

Urea Formaldehyde (U.F) - Electrical fittings

Epoxy Resin - Adhesives (Araldite)

Melamine Formaldehyde (M.F) - kitchen units, cups,plates etc

Common Thermoplastics and USES

ACRYLIC- plastic baths
PVC- guttering


POLYPROPYLENE - crates, chairs
NYLON - combs

A Strip-heater is shown below. Plastic can be heated by placing It along the top.