So, when was plastic born and how it diversifies into different types as today?
Plastic was introduced the first time at London’s Great International Exhibition in 1862. But it wasn’t until 1909 that the term “plastic” was used which is described as new class of materials which included “bakelite,” made from coal tar. That substance was used to produce many items such as telephones, cameras… Till the end of World War I, when petroleum was more available and easier to process than coal star, plastic became more popular. With its dominant feature of water resistance, strength, tough, plastic bags was put into common use.
Plastic bags are made from 3 main types of polyethylene: high-density polyethylene (HDPE), low-density polyethylene (LDPE), or linear low-density polyethylene (LLDPE) which is used for different uses. The main difference between those types is the degree of branching of the polymer chain. The degree of branching will affect tensile strength and crystallinity. The more branched a molecule is, the lower is its tensile strength and crystalline.
LDPE chains are branched, therefore, it is usually made with minimum thickness is 20mic. It is an excellent choice for shopping bags because it is thick, glossy and most beautifully printed. Therefore, companies which are manufacturers of clothing shops, garment items usually take advantages of these bags to advertise their brand name with logo, printing images on bags.
HDPE and LLDPE are composed of linear, unbranched chains. Because of its high density of monomers, plastic bags from those materials can be made very thin from 8mic. They are usually used for grocery because grocery and food items should be used only once, therefore, using very thin ones with no printing will be save much cost.
Moreover, one of very common complaints today about plastic bags is its existence for hundreds of years. This is a big harm for environments and makes people avoid using plastic bags. One solution for this issue is to produce biodegradable plastic bags. The products were invented to be made from starch which comes from corn or potatoes. This can converted into lactic acid which can be polymerized to biodegradable plastic. This additive only cost more usd 100/1 ton of plastic bags and this method has become a common solution for developed countries now such as EU, US…