The 1950s saw the beginning of the mass production of plastics. Over the decades, this has increased tremendously. In the ’50s, 1.7 million tons of plastic were being produced annually, but now in 2014, 311 million tons of plastics are being produced worldwide. However, the actual quantity is estimated to be even higher given that these figures do not take into account fibres made from polyamide(PA), poly-acrylic, poly-ethene terephthalate (PET), and polypropylene. Experts forecast that if the current rate of production and use doesn’t reduce, the mass production of industrial plastics could reach 2,000 million tons by 2050.
One of the main reasons why plastic is so popular is that it is cheap, light-weight, durable, and easily modifiable. The usage of plastic is expected to continue to grow. Plastics are widely used in almost all aspects of our day-to-day lives. In Europe, packaging accounts for 39.5% of plastic usage making it the largest sector utilising plastic followed by building and construction at 20.1% then the automotive industry at 8.6%. Plastic has also found its way into the electrical and electronic industry (5.7%) and agriculture (3.4%). When combined sectors like sport, furniture, consumer and household appliances, and health and safety account for 22.7% of the total plastic utilisation.
Despite the many benefits plastic offers, it is worth noting that the same properties that make it a great product present many disadvantages where the environment is concerned. For instance, its low cost means that it is easier to discard it after minimal use, its lightweight can cause it to end up far away from the source, and its durability means that it will last for a very long period in the environment. With new uses of plastic being discovered every day and plastic products reaching more people, the amount of plastic entering the environment is increasing rapidly. According to research, nearly 10% of all plastic litter ends up in our oceans and becomes marine litter.
Plastics are made up of polymers. A polymer is a large organic molecule that consists of repeating carbon-based chains. A polymer is produced when smaller molecules known as monomers are combined to form long carbon chains through a process known as polymerisation. Therefore, monomers are essentially the building blocks of polymers. If the polymer consists of repeating identical monomers, it is referred to as a homo-polymer. If the polymer consists of different types of monomers, it is known as a copolymer. The monomers are what determine the size, structure, and basic properties of polymers.
Ethylene, styrene, vinyl chloride, and propylene are some of the most commonly used monomers in plastic production. These monomers are primarily produced from petroleum as well as other fossil fuels. At the moment, about 4-6% of the global oil production is meant for plastic production. Besides fossil fuels, biomass such as plant oils is also used to create bioplastics. While biomass accounts for a very small percentage, its use is gradually increasing. But it is important to note that the oil or biomass used only provides the basic components of a polymer. Therefore, the properties of the end product aren’t influenced by the type of raw material used.
During plastic production, a wide range of chemicals are utilised as solvents, initiators, and catalysts of the production process. Catalysts and initiators facilitate polymerisation and are only used in limited quantities. Catalysts are primarily based on metals including magnesium, tin, zinc, titanium, or aluminium and can also include peroxides.
To aid the manufacturing processes of the polymer or alter the properties of the final product, later additives are usually added to the polymer. The production of plastic is to some extent dependent on additives as they are vital in creating or enhancing most of the key properties of plastics. The importance of additives is also demonstrated in the diverse range of additives – there are thousands of additives utilised in the production of plastic.