Plastic is not a nasty word!

The term plastic can be both a noun and an adjective. Plastic, the noun, refers to a wide range of synthetic materials that can be moulded in to shape. Plastic, the adjective, means that the shape of the material in question can be deformed permanently without fracturing when a force is applied. It means, therefore, that some plastics are not plastic.

Types of plastic (the noun) include vynil, polyethelene, epoxy resin and butadiene-rubber to name but a few. There are at least thirty different types and everyday ‘quality’ items such as computer casings, shoe soles and up-market car engine bay parts are made from them. So plastic is not really a cheap and nasty material at all. It is, however, a cheap material when mass production is considered as once the initial mould or former is created, the item can be reproduced many times over.

Plastics are formed into shapes in many ways:

EXTRUSION
Hot molten synthetic material is forced through a nozzle to produce lengths of special shapes like tubes and angled strips and sections for joining board materials, protective corners, kitchen cupboard door handles and guttering.

BLOW EXTRUSION
This is used for making plastic films and bags. While still hot and malleable, an extruded tube is inflated like a balloon. This stretches and thins the plastic. The inflated material is produced in such a length to allow the plastic to cool. The end of this ‘balloon’ is sealed with a roller mechanism to retain the air in and to flatten it. This cooled flattened tube is then wound on to a big roll.

INJECTION MOULDING
Hot molten synthetic material is injected into a mould to mass produce everyday items. The parts produced can be very small like a washer or large like a car part, dustbin lid or some planters.

BLOW MOULDING
A small amount of hot malleable synthetic material is injected into the end of a mould. Compressed air is used to inflate a ‘bubble’ inside the plastic. The plastic material swells and fills the mould. This method is used to manufacture bottles and some toys.

ROTATIONAL MOULDING
Plastic powder is scooped into a former. The former or mould is rotated over a heat source. As the mould increases in temperature, the powder melts and sticks to the inside of the mould. This method is used for large round items such as plant containers and water barrels.

COMPRESSION MOULDING
This method uses thermoset resins. These are resins that will not melt when reheated after manufacture. A dry powder is placed in a former which is then compressed and heated until the resin has cured. This is used for making ashtrays, plates, and electrical switches.

REACTION INJECTION MOULDING
A resin and hardener are mixed and injected in to a former. The materials react and combine to form a hard material used in car parts, bumpers and plastic food trays in supermarkets.

VACUUM FORMING
A sheet of plastic material is held in a frame and heated until flexible. A vacuum pump then draws the sheet into a former. Packaging for many consumer goods is produced this way.
Plastics can be made in to other shapes by fabrication. That is to say two shapes moulded in one of the above methods can be jointed with the application of heat and additional plastic to form a more complicated shape. There are other ways of manufacturing consumable items and these include GRP (glass fibre), wood machining, metal machining and metal moulding but plastic is usually the most economical. There is a large range of plant containers available made in all of these materials in various styles and colours.

Plastic is not a nasty word. Plastic is in fact a wonderful material!