Polythene Bags – The History and Uses

Polythene bags (polyethylene bags) were first made in the USA in 1957; they were used for the packaging of sandwiches, bread, fruits and vegetables. By 1966, almost one third of bakery products produced in the USA were packed in them. By 1973, the volume of polyethylene bags produced in Western Europe reached almost twelve-million units. In 1982, large shopping centers started to sell plastic bags with handles (the “T-shirt bags”). By 2002, the total yearly volume of plastic bags produced in the world reached five- trillion units.

Types of Polyethylene Bags

1. Transparent packaging made of low/high density polyethylene, which serves a protective function (protects the products from moisture and dirt). The leaders in the production of the finest packages of this type are China and Russia: they produce 5-micrometer-thin polythene bags.

2. T-shirt bags made of low-density “rustling” polyethylene or high-density “smooth” polyethylene, which received their name for the shape of their handles. They were the last to come onto the market, but they secured their positions in supermarkets and retail outlets.

3. Bags with patch and loop handles made of high/medium/low density polyethylene and laminates. They are the most difficult to produce. Their handles can be welded or glued.

4. Trash bags made of low/high density polyethylene, or from a mixture. They often have dyes added to their material. They are available without handles, with “T-shirt”-type handles, or with straps for tying.

5. Branded polythene bags – these often have a company trademark on them.

Polyethylene

Polyethylene is a thermoplastic ethylene polymer; it’s the most common plastic used in the world. It looks like a waxy white mass (thin sheets are transparent and colorless). This material is chemical and frost resistant; it’s an insulator and shock absorber; it softens when heated and solidifies when cooled. People sometimes confuse it with cellophane – a similar material of plant origin.

Polyethylene was invented by a German engineer in 1899, but didn’t become widespread back then. It started to become widespread in 1933 due to the efforts of two British engineers. First, it was used for telephone cables; in the 1950’s, it started to be used for polythene bags in the food industry.

Polyethylene is made by ethylene polymerization. They separate high-density, medium-density and low-density polyethylene. Polyethylene is water-resistant, and doesn’t react with alkali, salt solutions, or acids. It undergoes thermal aging with time.

Polyethylene Uses

– Packaging film.

– Packaging (bottles, plastic boxes, and bottle caps)

– Pipes (for sewerage, drainage, water supply, and gas supply).

– Insulating material.

– Powder for hot-melt glue.

– Armor for bullet-proof vests.

– Casing for boats and ATVs, parts and technical equipment, and household items.

– The “ultrahigh molecular polyethylene” is used in medicine for joint cartilage replacement.

Environmental Issues

The inexpensiveness of polythene bags leads to the fact that many of them are used for a very short time, and then discarded. Each year, there are approximately 5 trillion units used around the world. The millions of tons of plastic trash dumped into the oceans is still a battle that environmentalists are dealing with today.

write by Athelstan