Introduction to PolyethylenePolyethylene is the most produced and most popular plastic in the world with an annual global production of around 80 million tonnes. This polymer is reliable, solid, has almost unlimited uses and is certainly a real asset in the world of the materials. It can be made into soft and pliable products as well as into tough, hard and strong products and from the simplest to the most complex of shapes. It is used in everyday appliances, in packaging, clear food wrap, grocery bags, cling-foil, squeeze bottle, garbage bag, detergent bottles, pipes, toys, automobile fuel tanks and even bullet proof vests. Polyethylene is indeed an indispensable material and has earned a permanent and unchallenged position on the materials market. How is it made?
- Polyethylene is produced from naphtha or petroleum. Ethylene is released when naphtha is strongly heated and when the ethylene changes into polyethylene it looks like a warm, fluid pulp.
- Before it solidifies, the pulp is pushed through a plate with small holes.
- These tiny white transparent granules of ethylene parts produced will form the building blocks which are threaded together into strings or branches.
- Polyethylene produced at low pressure gives it a high density, HDPE, with the particles forming straight, strong and tightly packed branches giving it a firm and stiff structure.
- This is sturdy, inflexible and tough product is used in a wide range of applications from the gft-container and domestic products like bottles, clothes pegs, brush handles, paper-thin foil used for sandwich bags, pedal bin bags or packaging for vegetables, fruit or meats.
- Polyethylene manufactured at high pressure gives it a low density, LDPE with the particles forming a crisscross of branches and side branches making it lighter and more elastic.
- This soft, tough and flexible polyethylene is used to make strong, flexible consumer items, like screw caps and lids, insulation material and packaging materials such as the carrier bags and agricultural plastic.
- LLDPE is produced from a mixture of the two and thus contain characteristics from both. Both flexible and sturdy products are made from it like thinner foils and also for multi-layer packaging.
- LLDPE is extremely tough and inflexible. These features can be used for the production of larger items, like covers, storage bins and some types of containers.
- New production techniques have led to the development of new types of polyethylene which are able to meet modern needs.
- The new polyethylene, UHMWPE is really hardwearing and can resist higher temperatures making it extremely suitable for applications like gear wheels, gaskets, bearings, filters, cutting boards and hammers.
Advantages of Polyethylene
• It is one of the most environment-friendly materials
• It is an efficient raw material in that the global production of the material only uses up less than one percent of the total crude oil and natural gas per year.
• The manufacturing of polyethylene is relatively clean and with minimum emission of harmful substances and there is very little waste.
• It is a very good recycling material. Since it is a thermoplastic material it can be melted in unlimited times and new products can be made with it.
• Recycled polyethylene that can no longer be re-processed becomes the high quality fuel material for power supply.
• It has the ability to store or transport food, water and energy safely without loss or decay
• It is a good insulator, able to resist caustic materials, able to resist both tropical and cold temperatures.
Application of Polyethylene
Containers for chemicals
Video showing how it is produced Video courtesy of Royal Society of Chemistry