Plastics and Microplastics: A Historical Overview

The amalgamation of new synthetic chemicals with the engineering capabilities of mass production has made plastics one of the most popular materials in modern times. The discovery of vulcanization of natural rubber by Charles Goodyear [14] led to a number of attempts to develop synthetic polymers including polystyrene (PS) and polyvinyl chloride (PVC). The first synthetic polymer to initiate mass production was Bakelite, a phenol-formaldehyde resin, developed by the Belgian chemist Leo Baekeland in 1909 [15]. Around 1930, the modern forms of PVC, polyethylene terephthalate (PET), polyurethane (PUR) and a more processable PS, were developed [16]. The early 1950s witnessed the development of high-density polyethylene (HDPE) and polypropylene (PP). In the 1960s, the natural resources such as the bacterial fermentation of sugars and lipids were utilized for the development of plastic materials [17] which include polyhydroxyalkanoates (PHA), polylactides (PLA), aliphatic polyesters and polysaccharides [18]. PLA is a commonly used form of bioplastic in end-segment consumer market products these days.

Plastics

The term plastic is used to describe plastic polymers to which various additives are added to give desirable properties to the final product (OECD 2004). Plastics are generally categorized into two types: thermoplastic, which soften on hearing can be remolded, and thermosetting, where cross-linking in the polymers occurs and they cannot be re-softened and remolded [8].

The plastic industry is expertly advancing in the arena of nanotechnology innovation. The recent technological advances have introduced the development of newer applications of elements based on nanomaterials that are now producing plastic nanocomposites which include materials that are reinforced with nanofillers for weight reduction, carbon nanotubes (CNTs) for improved mechanical strength and nano-silver as an antimicrobial agent in plastic food packaging materials. However, microplastics have been studied mostly in the context of the marine environment and have been found to be a major constituent of anthropogenic marine debris [8]. By 2020, the share of nanocomposites among plastics in the US will be 7% [19]. It is estimated that only 9% of the 9 billion tons of plastic ever produced has been recycled according to Plastic Recycling Data from UN Environment 2018. If this situation continues, the landfills will have 12 billion tons of plastic waste by 2050. It is therefore suggested that a sustainable waste management and an alternative to plastic materials is needed. In India, 15,000 tons of plastic waste is generated daily, out of which only 9000 tons is collected and recycled; 60% of this plastic is recycled which is higher than the global average of 14%. The remaining plastic material that is not recycled goes to landfills and oceans. It is hazardous to both mammals and marine life, which finally enters the food chain. Every part of the world, even the Arctic ice and mountains are polluted with macro-, micro- and nanoplastic waste material.

 
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